3449405b1887b7b892f6f5c12e2be1dfcc716e30
123
Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
  AnachronautandClaude Opus 5
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3449405b18 |
Give the system another page of each memory
CosmOS had 1,161 bytes of Program Memory left before the address applications load at, and Tab completion is not going to fit in that with anything to spare. So the wall moves up one page: the system keeps below 0x4FFF and 0x2FFF, and an application is based at 0x5000 and 0x3000. A PAGE IS A CHEAP THING TO GIVE IT AND AN EXPENSIVE THING TO RUN OUT OF. An application still has 44K of Program Memory before the vector table and the largest one here uses 7.5K, so what was taken from applications is space nothing has ever asked for - while what the system gained is the difference between building the next thing and counting bytes while building it. Not doubling, which was the version that would have cost application space worth minding. One page, and the same again when it is needed. Nothing in the machine knows where the wall is, so this is 34 #Base lines, one threshold in the fault handler, and the table in the CosmOS README that Tests/docs.sh reads its limits out of. The native assembler's scratch map had to move with it, and docs.sh said so before anything ran: its data reached 0x40D6 and its buffers began at 0x4000, so they were sitting on its variables. That file already carries a paragraph about the floor coming up and the map staying where it was. It has happened twice now, and been caught by a check the first time wrote. Twenty three recordings are the same runs a page higher. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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f97d15de08 |
The font comes from a chip, not from RAM that remembers
videoReset zeroed video memory and then wrote the font and the sixteen colour schemes into it, and the comment above that said out loud what was wrong with it: "everything here is ordinary video memory". RAM does not wake up with anything in it. That was the last piece of magic in this device, and it looked harmless until something wanted the font BACK - a program that redefines a glyph had destroyed the only copy there was. So the device has a character generator, the way the machines this one is pretending to be really did, and the copy into RAM is a thing it DOES rather than a state it mysteriously starts in. Command port 0x39: bit 0 for the font, bit 1 for the schemes. THE RAM IS STILL RAM. A program may overwrite every glyph and every colour and should be able to, which is what makes this a tile engine rather than a text display. What changed is that it is no longer a one way door. NEITHER COMMAND CLEARS WHAT IT DOES NOT OWN. The font used to clear the whole of tile memory before writing itself, which was harmless while it happened only at reset and is wrong the moment a program can ask: a program that defined a tile of its own and then wanted its text back would have paid for it with the tile. The reason it is a chip rather than a file on the disk, which was the other candidate: the boot chain prints before CosmOS exists. Stage one prints "?" when there is nothing to boot, and if the font came off the disk then the message about the disk having failed would be the one thing that could not be drawn. A system that wants its own font still loads one over the top - the ROM is the floor, not the policy. Two things that had been worked around now simply work. The shell asks for both whenever a program exits, so a program that redefined a letter no longer leaves it unable to spell, and Grid no longer needs to have saved the screen to avoid handing back green text on blue. And the fault screen asks for the glyphs first, because a message spelled in somebody's tile graphics is no message at all. Five video checks. Two runs each for the font and the schemes, since the map holds a tile NUMBER and the glyph is looked up when the frame is drawn - so restoring changes every cell using it, including ones drawn before, and what the two runs differ by is the command. The third guards the decision not to clear: tile 200 has to survive the font coming back. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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c1b3c4c156 |
A rule for the bug that formatted a disk
falls-into-subroutine. The code above a label ends without going anywhere and the label is one something CALLs, so execution walks into the subroutine, reaches its RET, and returns to whatever the Stack happens to hold - because nobody called, there is no caller, and it goes somewhere nobody named. It is worth a rule because the symptom is nowhere near the cause and changes with the Stack. In CosmOS's monitor it was usually a byte that does not decode, in the middle of newLine; once it was inside sbfsFormat, and the machine formatted the disk it had booted from. Two exemptions, and both had to exist or the rule would have reported well written code: A TAIL CALL IS THE SAME SHAPE AND IS FINE. Falling out of one subroutine into another means the RET returns to the outer caller, which is real. So it only fires when nothing since the last branch or return was a call target either - which is the linter's usual trade of precision for being worth reading. AND osExit NEVER RETURNS. It is how a loaded program gives the machine back, and every program here ends with it and then writes its helpers underneath. Without that, twelve well written programs were reported. It is the one name from the system this tool knows, and the comment says why it is there. Also SRET, which stopsFallthrough did not list. It returns from a handler exactly as RET returns from a call, and leaving it out is a gap in every rule that asks what reaches an instruction. Load bearing rather than tidy: without it cosmos.asm reports a handler ending in SRET as falling into the routine written under it. A first pass over the file collects call targets, because a subroutine is very often called from further down than it is written. The corpus reports none of it, which is the point rather than a disappointment, and the Test Manual now says so - a baseline entry that is absent is otherwise indistinguishable from a rule that never runs. Checked against the version of cosmos.asm from before the fix, where it names the line. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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66be42d7bb |
A word the monitor does not know goes to the disk, not into the weeds
There was nothing at the end of the monitor's command list. An unrecognised word
fell off it and straight into sayPrompt - which is a ROUTINE, so its RET had
nothing of its own to return to and went wherever the Stack happened to be
pointing.
The user found it by typing a program's name at the monitor prompt, which is an
entirely reasonable thing to do: the monitor is a mode of the shell, so
everything the shell does is meant to work in it. What they got was a fault, and
before that a second prompt printed on top of the first - which is sayPrompt
doing exactly what it is for on its way past, and the tell that it had been
entered rather than called.
WHERE THAT RET WENT DECIDED HOW BAD IT WAS. Usually 0x0003, in the middle of
newLine, and the machine stopped on a byte that is not an instruction. Once it
was inside sbfsFormat, and the machine formatted the disk it had booted from -
the user's would not start again, and neither would mine, which is how I came to
have a reproduction before I had a diagnosis.
Pre-existing, and not recent: it is there at
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AnachronautandClaude Opus 5
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fd9c4c75f8 |
Tell the person where it hurts
A fault stopped the machine and printed a line to standard error. On a terminal that is a diagnosis. Behind a window it is a frozen picture and no reason at all, because the message went somewhere nobody was looking - the machine looked hung and was not. It had stopped, and said so invisibly. CosmOS catches all five faults now and says what happened on the screen, with the address, in red. A FAULT ENDS THE PROGRAM, NOT THE MACHINE. That is the answer to "carry on or start again", and it is not a compromise: a bare RETI from most of these meets the instruction that failed and fails again, so carrying on was never on offer. But the machine is almost never what is broken. Everything the shell puts back when a program exits - the Stack, its vectors, the drive, the working directory, the console, the screen - is exactly what wants putting back after one dies, so the handler sets a status and joins handleExit. You are back at the prompt, and the program is recorded as having STOPPED rather than finished, because saying "finished" under a red fault message would be the shell contradicting itself. A fault below where programs load is the system's own, and there is nothing to go back to. That one says so and stops. THE SCREEN GOES BACK TO A MODE TEXT CAN BE SEEN IN, and that is the part that matters rather than the part that is prettiest. A program that faulted in bitmap mode left the console with no text rows, so it draws nothing at all: the message would be perfectly correct and completely invisible, which is the one thing it must never be. Two palette entries go back for the same reason, since a program that wrote its own colours can leave every ink the same as every paper. Only the two the message needs, so the rest of what the program chose is left alone. Both halves are checked by looking at the PICTURE, because the serial line was never where the problem was. Crash blind ruins the palette and drops into bitmap mode before it faults; without the mode the screen comes back 320 by 200 with nothing on it, and without the palette it is the right size with the message present and unreadable. Each break loses the red on its own. Crash is also a program worth having: it breaks in whichever of the five ways you name, so a fault screen can be looked at without having written a bug first. Two things found on the way: The native assembler keeps its OWN copy of the reserved vector names, so it did not know NoHandler or NoDevice and built a cosmos.bin that differed from the host assembler's. Caught by native.sh, which is exactly the drift that test exists for. And cosmosMonitor had dead input. It assembles code into 0x8000 and runs it, and that code faults - which used to kill the machine, so everything after it in the file had never run. It runs now, and the recording grew by sixty lines of monitor session that had been unreachable since the day the fault was put there. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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000a6d39cb |
Somewhere to send the fault about there being nowhere to send it
Dispatching through a vector with nothing in it was the one fault this machine could not hand over, because the thing that would hand it over is the thing that has just found nothing to hand it to. It stopped the machine and no program could do anything about it - so calling a service the system does not implement was fatal, and that is an ordinary mistake to make. Two new fault vectors: 5 when a software vector was empty, 6 when a device interrupted and its hardware entry was. Separate, because they are separate mistakes with separate fixes - one is a program calling something that is not there, the other a program that asked to be interrupted and forgot the handler. WHICH ENTRY WAS EMPTY ARRIVES IN Q, and it is the only thing on this machine a handler is given in a register. Not a fault cause register by another route: the vector still says what happened and Q says which of the 256 entries it happened about, which is a parameter and not a cause. It costs no new state at all, because the frame already saved the Q the interrupted program had and RETI puts it back. The escalation happens once. If vector 5 or 6 is itself empty the machine stops the way it always did, having genuinely run out of places to go. swiFaultTest is what guards that, and it was written long before any of this: it installs nothing, so it must still get the old halt. Breaking the escalation fails the two new tests and not that one; making the escalation unbounded fails that one and not the two new ones. Each break fails exactly the half it belongs to. noDeviceTest is fed no input on purpose. The console raises its line once when input ENDS as well as when a byte arrives - which exists so a program driven by interrupts is told when nothing more is coming - so with no input at all, that end is what turns up. Groundwork for CosmOS's fault screen, which wanted to catch these two and could not. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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4d976fc22a |
A program reading a line gets the editing too
osReadLine goes through the shell's editor now, so anything that asks the system for a line gets arrows, Home, End and Delete. The editor is a program, and a word typed with two letters the wrong way round can be put right without starting the line again. IT DOES NOT GET THE HISTORY, and that is the interesting half. Edit would otherwise fill the history with the text of somebody's document, and pressing Up in the middle of writing one would put "dir" into it. The history belongs to the thing whose lines are commands. Two entry points rather than a flag the caller sets first, so a caller cannot forget which it wanted. And the console is put back the way it was FOUND rather than the way the shell likes it. A program that had asked for key mode and then read a line through the system used to be handed back a console in line mode having asked for nothing of the sort. The status port reports all three things the control port can ask for, in the same order two bits along, so one shift turns what the console IS into what to write to make it that again. Which uncovered a real fault in the console. READING THE STATUS PORT WAS EATING A KEY: in line mode the poll consumed an arrow key and dropped it, so a program that looked and then asked for key mode - exactly what reading a line now does - found the first key it was reaching for already gone. A look must not consume what it cannot report, because the mode can change. It is held now and delivered as soon as something will take it. A blocking read still discards it, and must: that read IS the delivery, and a byte held there would be met again forever. Four recordings gained a program's echo, and cosmosEdit's went from "> : : : : > : : > 1: alpha" to a session you can read. VERIFIED THE SAME WAY AS BEFORE: with only the program side of the echo silenced, all 192 tests pass against the recordings as they were before this commit, so the echo is the whole of what changed. cosmosEditService is the new test and it checks both halves at once. Inside Edit, Left/Delete/Left puts "alpah" right. Up and Down do nothing there - were a program's line walking the shell's history, the next line would come out as the echo command from the top of the file instead of the word. And one press of Up back at the prompt finds the command typed before Edit was started, which is the proof that nothing the editor read went into the history at all. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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71f6e215f9 |
The shell remembers what was typed before it
Up walks back through the last eight lines and Down forward again. It exists only because the keys reach the system now: until A1 and A2 there was nothing to press Up at, and the line was assembled somewhere the shell could not see. A RING RATHER THAN A LIST. A ninth line pushes the oldest out by moving where the ring starts, not by moving any of the lines - so keeping a line costs a copy of that line and nothing else, however full the history is. Eight is a power of two, so which slot an entry lives in is an AND. The ISA had the awkward part already: A and B are a sixteen bit shift register, so one SHR with B empty turns a slot number into the offset of a 128 byte slot, high byte and low, ready for DPUW. A NINTH SLOT HOLDS WHAT WAS BEING TYPED when Up left it, and Down brings it back. Losing a half written line to a keypress is the sort of small rudeness that makes a thing unpleasant to use, and it costs one slot to avoid. An empty line is not kept, and neither is one the same as the line already at the top. The test proves the second by looking one further back: if a repeated command were kept twice, the line behind the newest would be the same line again. The redraw had to learn to rub out. One space was enough while the only thing that shortened a line was taking one character out of it; a recalled line replaces the whole of it, and a short line over a long one left the tail of the long one on screen looking like part of what you were typing. It now covers exactly what was lost - which turned out to be one space fewer than before in the cases that GREW, so two lines of cosmosEditKeys lost a trailing space that was never doing anything. Costs 1157 bytes of Data Memory, taking CosmOS to 6220 of the 8192 it has before a loaded program's data begins. Worth writing down: that is the budget, and this is the largest single thing in it. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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81e544eb3d |
Load a program that has no data
A five instruction program that writes one port and exits has no Data Segment at all, and the loader stopped the machine dead on it. It asked the memory controller to move a segment of no bytes, and a length of zero asks for the whole 64K - which is the machine's rule, and a reasonable one, since two bytes cannot say 65536 and a transfer of nothing is not usually what anybody meant. It is exactly what was meant here. 64K did not fit, the controller refused, and the load stopped half done. ON A TERMINAL THAT PRINTS A FAULT WITH AN ADDRESS. Behind a window it is a frozen picture and no reason at all, which is how it was found and is a separate problem from this one. The header says how long each segment is, so the loader knows before it asks. Both bytes are already in hand, so the test costs one OR. Nothing is lost by skipping the transfer: a blit leaves the controller's addresses past whatever it touched, and a blit of nothing would have left them where they already are, which is where the vectors are read from next. Guarded for the code segment too. A program with no code is equally assemblable and would have stopped in exactly the same place. Mode.sbx is the fix's test and a program worth having on its own: forty columns or eighty, whichever the screen is not in, which is what a person wanting Snake drawn twice the size actually needs. Ten instructions and no data, deliberately - it prints its two digits a register at a time rather than from a string, so it stays the smallest shape a loadable program can take. Nothing else on that disk had ever been that shape, which is why nothing had ever tried it. Reported by the user, who wrote the program. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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373454ec00 |
A fresh disk for every test, fixtures included
A fixture built by makedisks.sh was handed to each test where it lay. Twenty four tests name disks/cosmos.img and several of them write to one, so a test could hand the next one a disk with its leavings on. romBoot is what found it. Its recorded output described a directory that selfBoot had made earlier in the same run, so it passed in a full run and failed on its own - which is the worst way round for a test to be wrong, because the form nobody runs is the one telling the truth. Its recording now says "made" like selfBoot's, which is what running the same input on the same disk should always have said. Fixed as a class rather than as an instance: run.sh copies a fixture before attaching it, the same way it already removed a scratch image. Then every one of the 138 run and rom tests was run on its own to see whether anything else was leaning on what ran before it. Nothing was, before or after. Also, cosmosEditKeys.in was written by Python's write_text, which encodes as UTF-8, so every key byte was 0xC2 and then the key. The test passed anyway, because the shell ignores a byte it has no use for - a fixture working for a reason it was not built on, which is exactly the thing that stops working without anybody touching it. Written as bytes now; the recording is unchanged, which is the proof the stray bytes were being ignored. docs.sh is what caught that, and it turns out to draw the line in the right place by construction: a deliberately binary fixture does not decode as UTF-8 and is skipped, while one that is accidentally UTF-8 decodes and is reported. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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736037462e |
The shell edits the line it is given
Three different things used to do this job, and which one you got depended on where the machine was running. On a terminal the host held the line and did the echoing and the backspacing; behind a window the console's own gatherer did it; from a file nothing did it at all. One job, three implementations, none of them in the system - which is why there was no way to move about in a line and nowhere for a history to live. So editLine does it. Key mode while a line is being read and line mode straight after, so nothing else in the system and no program calling osReadLine notices anything changed. Left and Right, Home and End, Backspace for the character before the cursor and Delete for the one under it, and anything typed goes in where the cursor is with the rest of the line moving along. Ctrl-D means the end of input again, on an empty line, because that was a thing the terminal did while it was holding the line and it is not holding it now. Same trade as the echoing. MOST KEYSTROKES DRAW NOTHING BUT THEMSELVES. A character typed at the end of a line needs no cursor moved: printing it is the whole change, and a backspace there is three ordinary bytes. That matters beyond speed - moving the cursor by hand is what a terminal is TOLD about, in an escape sequence, so redrawing on every keypress would fill every recorded transcript in this suite with them. The line is only reprinted when something happened in the middle of it. Where the line STARTS is worked out backwards from where printing ended, rather than trusted from what was remembered. That is what makes it survive the screen scrolling: a line printed on the bottom row moves everything up by one, and a remembered row would be one too low from then on. The command line holds 127 characters, up from 63. The limit started to be felt the moment a line could be moved about in. 58 recordings changed, and every one of them by the echo. THE PROOF IS NOT A HEURISTIC: a CosmOS built with the echo silenced reproduces 187 of the 188 recordings byte for byte. The one exception is cosmosTyped, the backspace test, where the rub-out marks now come from the shell instead of from the console's gatherer - same marks, different author. cosmosEditKeys is the new test, and every line in it is typed wrong and then corrected with a different key. Its last line is eighty six characters at a prompt in column two on an eighty column screen, so the line runs onto the row below and the shell has to find the start of something it can no longer see; breaking either half of that arithmetic fails it. Also: agree.sh looked for "> the same", anchored to a prompt that no longer precedes what a command prints. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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b3726c950a |
Deliver the keys that are not characters
An arrow key has never reached this machine. Voyager threw it away for want of anywhere to put it, and a terminal sent ESC [ A, which arrived in the middle of whatever was being read and made it unrecognisable - typing Up at the CosmOS prompt put three bytes in the command line and got "I do not know". So the console names them: one byte each, 0x80 upward, above ASCII so nothing written before them can collide. Up, Down, Left, Right, Home, End and forward Delete, with room above for the paging and function keys. The console normalises, which is what it already does. Behind a window it turns the key somebody pressed into a byte; on a terminal it turns the sequence into the same byte. That is the act it has always performed on Return and Backspace, one layer further along, and it is why a program need not know which of the two it is talking to. What a key MEANS is not the console's business - that belongs to whoever is reading, the same way what is on a disk belongs to the system and what a drive is belongs to the machine. Translated only when standard input really is a terminal. Nothing else sends these sequences, a pipe holds exactly the bytes somebody put in it, and it keeps the Escape-or-Up timing problem out of every test here: a test writes the key values themselves. Line mode drops them, in both front ends, because line mode delivers characters and a line somebody else has finished editing cannot be moved about in. Press.sbx says what it was handed, in hexadecimal and by name, and reads a line before it reads keys so both halves of that rule are checked. Two recordings, one fed as standard input and one as a keyboard, agreeing byte for byte; each break fails exactly one of them. Three checks in terminal.sh type real escape sequences at a pseudo-terminal, which is the only place they are ever read as sequences: that they arrive as keys, that Escape alone is still Escape, and that a character typed straight after an escape is held rather than swallowed. Five recordings re-blessed for Press.sbx appearing on the shared disk, and the whole of that diff is the file's own line and the counts above it. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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2a29cebc6b |
Make the screen come back on the machine people actually run
Found by running it: Grid exits and the shell prints its prompt into the grid, with the view up to seven pixels out of alignment. Three faults, and the first is the one that made the other two visible. MAKE RUN-VOYAGER HAD NO SCRATCH DRIVE. It gives drive 1 to Disks/personal.img, which is a file and not volatile, so there was nowhere to keep a screen - osTakeScreen answered no and the whole feature silently did not happen. It was tested with --ram-disk and shipped without one, which is as good a description of testing the wrong machine as I can write. There is now a RAM disk in drive 2, after the personal disk so that drive 1 stays the one that is yours. A PROGRAM TOLD NO MUST COPE. A refusal is not a fault, it means doing what the program did before there was anywhere to save a screen. Grid deleted its own tidying up when it started asking, so being refused left the grid on screen with a prompt written into it. It clears up again when refused, and only then. AND THE SYSTEM ALWAYS LEAVES THE SCREEN USABLE. The fine scroll registers go back to zero at every program exit, whether or not the picture could be saved: the console draws in whole cells, so a view three pixels into one puts every character three pixels out for ever. That is not part of saving a screen and should never have depended on it. Both paths are checked now. With a scratch drive the screen comes back cell for cell; without one, no grid is left behind. Breaking either fails one of them and not the other. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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ab72443b99 |
Give the screen back: osTakeScreen, and the RAM disk earns its keep
A program that takes the whole screen leaves the shell a blank one, and
whatever was on it is gone. There was nowhere to put 48K of video memory on
a machine with 64K of Data Memory that CosmOS already lives in.
A DRIVE MADE OF MEMORY IS SOMEWHERE. The screen goes to a file on the
scratch drive - the first volatile drive found at boot - like any other
file, and comes back from handleExit alongside the vectors and console mode
already put back there. The filesystem does the allocating, so this
invented nothing: it is 196 pages of tiles, map and palette, with a block
on the front holding the cursor, the four scroll registers and the mode.
NOT AUTOMATIC, and that is the whole design. Saving on every program start
would be cheap enough; restoring on every exit would be wrong, because dir
and Files and Say print and stop and their output is the reason you ran
them. A program says it took the screen, and one that says nothing behaves
exactly as every program did before this existed.
It deleted thirty lines of Grid, and they were all wrong anyway: four
scroll registers put back by hand, the map filled with spaces, the cursor
sent home, palette bank 0 written out - and the other fifteen banks kept
Grid's colours, because there was nowhere to have kept the real ones. Grid
is 64 bytes smaller and gives back what was actually there.
The check compares the screen before against the screen after, CELL BY
CELL, and allows only the rows around the cursor to differ - found from
where the text ends rather than guessed at, because the first version
assumed the cursor was near the bottom of the screen and let three real
differences through.
Two things cost time and neither was the feature:
- An edit adding "SWI osTakeScreen" to Grid was in the same script as a
failing s.index, so the file was never written - and the COMMENT
describing the call did land, from a later edit. Grid documented a call
it did not make, and read as though it should have worked.
- docs.sh caught osTakeScreen having no row in the services table, which
is the check the service layer added for exactly this and the second
time it has earned itself.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
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AnachronautandClaude Opus 5
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04f1ffabd4 |
A disk made of memory, brought up by whoever owns it
THE MACHINE SUPPLIES BLOCKS AND SAYS WHAT A DRIVE IS. It says nothing about filesystems, which is what leaves room for a system that would rather have its own - and is why the volatile bit is a fact about the hardware rather than a promise about SBFS. 0x26 what the selected drive is: bit 0, contents do not survive 0x27, 0x28 how many blocks it has --ram-disk N a drive of N blocks with memory behind it A drive of memory selects, reads, writes and has a size like any other, and a program cannot tell the difference except by how fast it was. The one thing it cannot work out for itself is that the contents are volatile, because an empty disk and a volatile disk look identical from outside. THAT BIT IS THE DIFFERENCE BETWEEN A DRIVE A SYSTEM MAY FORMAT ON SIGHT AND ONE IT MUST NOT. CosmOS formats a volatile drive it cannot read, because there was never anything on it to lose, and leaves every other unreadable drive alone - an unformatted floppy is not an invitation, it is a blank floppy. Removing that check formats somebody's blank disk, which is checked rather than asserted: cosmosBlankDisk boots with one and requires it to be refused. So CosmOS grew a format. The size comes from the drive rather than from a superblock, since a superblock states a size too and that is no use on a disk which has not got one yet. Sixteen directory blocks, 128 names, chosen rather than worked out: a scratch disk runs out of names long before room, and this machine cannot divide. The RAM disk is no faster on this emulator by default, and that is honest rather than disappointing: the emulated disk has no seek time unless asked for one. With --disk-cycles 10000 the same copy is 7.94M cycles against 8.70M, the difference being every write. run.sh takes "ram:2048" where an image name goes, which needs no removing between runs because there is nothing to remove. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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6b51d6391f |
A beat a program sets for itself
The only regular thing on this machine was the screen finishing a frame, sixty times a second and not negotiable - a clock a program BORROWS rather than one it sets. Every duration became a multiple of 16,667 cycles, so a sixteenth note at 120 beats a minute, which is 125,000, is seven and a half frames and cannot be asked for at all. The way round it was to choose a tempo whose subdivisions happen to land on whole frames, which is making the music fit the machine. Examples/tune.asm says so in its own header. 0x50 Status: a period went by, it is running, it will interrupt 0x51 Control: run, repeat, interrupt 0x52-0x54 The period, in cycles, most significant first THE PERIOD IS IN CYCLES because that is what everything else here is counted in - the cost model counts them and a frame is measured in them - so a timer counting anything else would be a second unit to remember. Twenty four bits reaches from one cycle to sixteen and a half seconds, with 120 beats a minute at 500,000 in the middle, and there is no range left for a prescaler to buy. Starting loads the period; asking it to run while it already is does not, so turning interrupts on half way through a period does not silently move the beat being kept. What is left over carries into the next period, so a period of 1,000 ticks every 1,000 and not every 1,000 plus however late anybody looked. Reading the status takes the tick down and the line with it, which is the rule this machine settled two days ago about every status port. The timing check is in terminal.sh and not the manifest, and the reason is worth keeping: settle() strips cycle counts from recordings, which is right for every other program and useless for a clock. "It printed eight dots" would pass on a timer that fired them all at once. terminal.sh measures that eight periods of 125,000 come to a million within a couple of hundred cycles, and that 99.97% of them were spent asleep. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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e4f4bae762 |
Work across two disks: copy between them, and run a program from one on
files from the other Two things anybody expects of a second disk, and each needed something different. COPYING NEEDED TWO THINGS TO REMEMBER A DRIVE. The write stream is the only thing here that lives across service calls, so it is the only thing whose drive can change underneath it: every osFileBlock names its source path again and goes back to the source drive, and then osFileWrite has to come home. It records the drive it was opened on and returns there. And the file lookup CACHE. It keeps the last path resolved so a reader walking a file does not re-walk the directory for every block - and skipping the walk skipped the drive the path named, so block one of a cross-drive copy read the source's block numbers off the DESTINATION disk. It only showed on files of more than one block, because a file of one is never looked up twice. One block worked and two did not, which is a suspicious enough shape to have suspected sooner. RUNNING A PROGRAM FROM ELSEWHERE NEEDED A THIRD PLACE TO LOOK, and two restorations. The shell tried where you are and /Apps on the disk you are on. It now tries /Apps on drive 0 as well, which is what makes the system's programs work from a disk of your own - one with your files on it and no system, which is most of the point of having a second disk. The drive goes back after the load, because by then the program is in memory and the blocks it came from mean nothing; and again when it exits, because a program that copies between disks moves the drive as its own paths need to and being left wherever it finished is not what was asked for. Copy 1:/a 0:/b now leaves you exactly where you were. The fixture disk grew an /Apps, because it kept its programs at the root and so could not exercise the third place at all. Two hours of the debugging above were spent on a stale disk image. The machine boots the system that is ON the image, so a rebuilt cosmos.bin means nothing until the image is rebuilt too - and the trace said my new code never ran, which was true. Third time this project has been misled by one. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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4cc6393f5b |
Name a drive in a path
"1:/notes", or "1:" on its own for wherever that drive already was. Done in sbfsWalk, which is where every path in the system arrives - eight callers between the shell, the config reader and the filesystem - so it works for anything that takes a path rather than for whichever commands somebody remembered to change. NAMING A DRIVE GOES THERE AND STAYS THERE. Switching for the length of one command and switching back reads better and cannot work: a path resolves to a start block and a length, and those mean nothing without the drive they were read from. A load that resolved on drive 1 and then read its blocks on drive 0 would read the right blocks of the wrong disk. A name beginning with a digit is still a name. The colon is the whole of what tells them apart, and /2things is on the fixture disk to keep it that way. Two bugs, and the second is the interesting one. SUB sets carry on a BORROW, so a character below '0' leaves it set - and the test for "not a digit" branched on clear. Every prefix was ignored. Then the leading-separator test reads the first character through DP0, which sbfsPathDrive could not move because RET puts DP0 back the way it found it. It advanced SbfsPathAt and DP0 still pointed at the digit, so every prefixed path was judged relative and walked from the named drive's working directory. IT ONLY SHOWED WHEN THAT DRIVE WAS STANDING SOMEWHERE OTHER THAN ITS ROOT, because a relative walk from the root is an absolute one - so "cd 1:/2things" worked from a fresh boot and failed after "cd 1:/notes". The test does it in that order for that reason. Copying between two disks is still not one command: each path resolves on its own drive and the drive stays where the last path left it. That wants Copy to change drives between blocks. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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5644c24113 |
CosmOS knows about all four drives
A mounted disk is EIGHT BYTES - where its directory starts, how many
blocks it is, how big the disk is, and where you are on it. They now sit
together in the data segment, and changing drives is one copy out and one
copy in. The other three thousand lines of filesystem go on reading the
same four names they always have and never learn there is more than one
disk, which is the whole reason this was affordable.
The version is not in the record. It is checked at mount and thrown away,
because a version one disk's zero parent already reads as "in the root".
Every drive is mounted at boot: the controller says how many are plugged
in and each is tried in turn. One with nothing in it, or a disk this
cannot read, is left unmounted rather than stopping the others, so a
machine with a good disk in drive 0 and a blank in drive 1 starts.
'drive' says which one, 'drive 1' goes to another, and the working
directory goes with it - where you are on a disk is part of which disk you
are on. A drive the machine has not got is refused, and refused
differently from one that is there with nothing readable in it.
Three things the assembly caught me on, all the same misunderstanding of
what survives a call:
- OR reads A and B, and the bit came back from sbfsDriveBit in Q, which
RET does not disturb - but RET does put A back. The mounted mask never
got set and drive 0 was reported unmountable.
- MVQA then RSTA throws away the copy it just made, so doubling a bit
doubled nothing. SHL does it in one instruction, because A and B are
one register to it.
- There is no move from A to B. INB reads a port straight into B, which
is what the drive count comparison wanted.
run.sh takes more than one image now, separated by a plus, since the
machine has four drives and a test that could only name one could not
check any of this.
The buffer note is forgotten on a drive change and that is DELIBERATELY
kept although nothing can currently reach it: only the file read-ahead
consults it, a directory scan does not, and finding a file requires a
scan which overwrites the note on the way past. Two disks were built with
the same file at the same block to try to catch it and the answer was
right either way. Three instructions to hold an invariant rather than a
story about a bug - and the comment says so instead of claiming a fix.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
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AnachronautandClaude Opus 5
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b1538e0618 |
Give the disk four drives, behind one controller
SEVERAL DISKS ARE ONE CONTROLLER AND NOT SEVERAL DEVICES, and the instruction set decided that rather than taste. A port is an immediate byte inside the OUT that names it - portOut takes it from Program Memory - so a program cannot compute one. "The disk on port 0x20 plus drive times four" is not something this machine can say, and two disks as two devices would mean a branch on the drive number in all eleven places sbfs.asm names a disk port. A drive register is what a floppy controller has always been. 0x24 Drive, which the block, command and status registers refer to 0x25 Drives, read only: how many are plugged in --disk given more than once fills them in order. What is per drive is the image, its size and its write protection; the block register, the status and the one buffer belong to the controller, which is the same division real hardware makes. A drive that is not there is refused rather than wrapped, because wrapping means a program asking for a drive this machine has not got quietly reading the one it has - the same shape of fault as taking a bank number somebody else was using. An EMPTY drive is a different thing and is selectable: a controller has its drives whether or not there are disks in them, and reading one fails with the error bit the way an empty drive should. Changing drives finishes whatever the one being left was in the middle of. A transfer waits for the clock, so one may be owed at any moment, and running it against the disk that is arriving would be a fault with no owner. Also stops parseOptions setting its defaults field by field. It was nine assignments beside a struct, and a list beside a thing drifts from the thing: adding two fields left them holding whatever was on the stack, so a machine given one disk was told it already had four drives. It is one zeroing now, and a default that is not nought can be written under it where it reads as the exception. That struct growing a field once before left Voyager linked against an object that disagreed about its size. Nothing in CosmOS uses any of this yet. The mount record is next. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
|
3b650cabcd |
Grid took the disk's bank number, and gave the screen back untidy
Found by playing with it: after running Grid, the shell could not start anything by name and dir said the disk was empty. Several commands after the program that did it had exited, and nothing had said a word. BANK NUMBERS ARE ONE NAMESPACE FOR THE WHOLE MACHINE. Grid registered video memory as bank 3, which is the number CosmOS gives the disk's buffer when it mounts - and that does not fail, it succeeds. Every read the filesystem made afterwards came out of video memory. Grid uses 4 now, and the CosmOS README has a table of who owns what, because the one place this was written down was a line in a service description about sbfsMount. Nothing hands bank numbers out and nothing refuses one that is taken. If programs start wanting banks routinely, a service that allocates them is what should exist rather than a longer table - noted there rather than built, since one program wanting one bank is not yet a system. Also puts the cursor home on the way out. The map was emptied and the console was not told, so the shell carried on writing from wherever the cursor had been standing when Grid started - twelve rows down a screen with nothing on it. Clearing is what homes a cursor and it costs one write. The regression test runs a program by name, then Grid, then the same program again; the second one is the check. Putting Grid back on bank 3 fails it. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
|
1aa45fcfc4 |
Grid: fill the map, not the window
Scrolling sideways walked off the end of what the program had filled, so the grid went blank for six seconds and then came round again. A map row holds 128 cells - 256 bytes at two a cell, whatever mode the screen is in - and an eighty column screen shows eighty of them, so 48 were empty. This is the third thing this loop has counted and the first right one. It said forty, which filled half the screen. Then it asked the screen how wide it was, which fixed what could be seen and was still wrong. ASKING THE SCREEN IS RIGHT FOR FILLING A SCREEN AND WRONG FOR FILLING A MAP: a program writing one screenful wants the window, and a program that scrolls wants everything the window can be moved over. There is no register for that because it is a property of video memory rather than of the display. The check that should have caught it did not, and that is the more useful half. periodic.py looked at 32 pixels - four cells at the left edge - so it could not see a gap that was on the right, and at the cycle count it samples the origin had moved to column 22 and the gap was off in the middle distance. It reads the whole scanline now and says which column the picture stops repeating at, which is how the two failures above were told apart. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
|
bcd42e75ca |
Scroll the screen sideways, and by less than a cell
The screen could move one way, a cell at a time. Three registers were missing and this adds them: a column origin so the map can be wider than the screen as well as taller, and a pixel remainder for each axis so the step can be one pixel rather than eight. 0x36 Scroll column, in cells, wrapping at 128 0x37 Fine X, 0 to 7 pixels 0x38 Fine Y, 0 to 7 pixels FINE DOES NOT CARRY INTO COARSE. Writing 8 to a fine register writes 0, because only its low three bits mean anything. The alternative was for a write of 8 to step the coarse register, and it was rejected for one reason: a program that scrolls has to know where it has got to, and if the hardware carries then the only way to find out is to read the register back. Keeping them apart means the program already knows, because it did the arithmetic itself. It is also what the machines this one is pretending to be did. The renderer now draws one more row and one more column than fit and clips them, because with a fine offset the screen no longer begins on a cell boundary and the cells at two edges are partly off it. videoPutCell follows the column origin as it has always followed the row - a caller means a cell of the SCREEN, and the screen is a window onto the map. The fine offsets are deliberately not applied there: they move the finished picture by less than a cell, and there is no such thing as less than a cell to write into. So a program may scroll to any pixel without the console's idea of where row three, column five is moving underneath it. Grid now scrolls diagonally, a pixel a frame, in four port writes and two carries. It moved eight pixels every fourth frame before, which reads as the picture jumping rather than travelling. Seven checks, each one the same program with one register changed, so what is compared is where the picture stopped. Breaking fine X, fine Y, the column origin, the three-bit mask, or the console's use of the origin each fails exactly one of them. Grid's own two checks had to be rewritten, and the reason is worth keeping: they asked whether pixel 4 was a grid line, which was really a check that the scroll happened to be at a cell boundary. A picture that moves a pixel a frame can only be asked things that are true at every offset - that it repeats every eight pixels, and that one band of eight rows holds different colours from the next. Also repairs docs.sh, which found the minimal CosmOS application by taking the first asm block in the README. Documenting a program with an example above it made that a different block, and the check complained that the minimal application had no #Base about something that never claimed to be one. It looks under System Services now. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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1a8a5efe03 |
Grid: the first program to use the screen as a screen
Everything drawn on this machine so far has been text or a bitmap. The tile
engine has been there since the screen was built and only the console had
touched it, and only ever to put a letter in a cell - the one thing it can
do that a plain character display could do too.
Grid redefines a tile, fills all 128 map rows with it, and scrolls by
writing ONE BYTE A FRAME. Nothing moves. The rows above and below the
screen are already drawn, so a screenful of movement costs one OUTA and the
rows that leave the top are still there.
Its tile goes at 200 because the machine wakes with the font in tile memory
- glyph n at tile n, for 135 of the 256 - so a program starting at zero
paints over the alphabet and the shell it is about to hand the machine back
to. Its sixteen colour bands are one tile and not sixteen: the attribute
nibble is added to every index in a cell, so the same 64 bytes come out in
sixteen colourings.
Three things it cost, all of them the same lesson about this machine:
- "SETD.0 X" then "STD.0.1" stores through DP1, which had not been set
yet. It assembles, and the blit then reads its 64 bytes from wherever
DP1 was last left, so the tile came out as noise.
- The palette entry for scheme n is at 0xFC00 + 64n, which reaches
0xFFC0 - four pages, not one. And doubling A by adding B needs B to
hold A, which RSTB is the opposite of. Both went away by writing all
256 entries in order and letting the controller step the address, so
nothing computes an address at all.
- The screen it hands back had the right cells and the wrong colours,
because restoring the map is not restoring the palette.
That last one is a gap in the machine rather than in this program, and is
written up in the CosmOS README. The console's colours live at exactly the
entries the attribute nibble lands on, so any program using the nibble
overwrites them and has nowhere else to write. Grid puts bank 0 back - grey
on black - and leaves the other fifteen. The real answer is a command to
the screen meaning "give me back what you woke up with", the way the
console has one for clearing. There is not one, and this is the first
program that ever wanted it.
Two checks in video.sh, which boots the whole system and reads the pixels
the renderer produced rather than trusting what the program believed.
Breaking the tile fails one and breaking the attribute fails the other.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
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AnachronautandClaude Opus 5
|
0e0731e2b1 |
Put the cursor home when the screen is cleared
A screen with nothing on it and a cursor half way down it is not a cleared screen: the next thing written lands where the last thing happened to leave off, at a position whose meaning was just erased. The shell's clear did exactly that, and left the next line one row below wherever it had been. Both halves were missing. consoleClearScreen blanks the cells and does not touch cursorRow or cursorColumn, and 2J on a terminal empties the screen without moving anything - H is what puts the cursor at the top. Life and Snake never showed this because they follow their clear with an explicit 1;1H of their own. They were working around it, which is why the bug survived until a command cleared the screen and then let somebody type. The attribute is deliberately not reset. Clearing is about what is on the screen rather than how the next thing will be drawn, and a program that chose a colour and then cleared still wants that colour - which is what a terminal does too. Two checks in video.sh, and they took two goes to make independent. The first pointed at the row where the letter lands when the cursor is NOT homed, so removing the clear and removing the homing failed the same pair and neither said which. The second now looks at a row nothing writes to either way - and at a letter whose ink actually reaches the pixel it reads, which "two" did not, so it passed on a screen that had never been cleared. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
|
553882d28d |
Start CosmOS with a script, and let a script hold its tongue
Three things scripts wanted, and they are one thing: a machine that can have a face. /System/Boot/startup.sh runs before anybody can type. Every way of reaching the prompt for the first time goes through it, including the one where there is no disk - in which case there is nothing to find and nothing is said. A MISSING one is ordinary and silent, because a clean install has none and a machine that complained every boot about a file nobody wrote would be teaching its owner to ignore it. One that is THERE and does not begin with #! is the other case entirely: somebody meant that to run. #quiet stops each line being echoed, #loud puts it back. The prompt and the echo go together, because together they are what makes a script look like typing, so a quiet script gets neither and what it prints is all that appears. A nested script inherits quiet - a build that asked for it meant its helpers too - and gets its own setting back when the helper returns. Anything else beginning with # is handed to the shell, which does not know it and stops the script, because a script that asked for something this shell cannot do should not carry on as though it had been given it. clear empties the screen, which the console has been able to do since before there was a screen to do it on. THE PROMPT IS NOW SAID BY WHOEVER SUPPLIES THE LINE. It used to be said at the top of the loop, which is a decision made before the line is read and an answer not known until after - and it was wrong at both ends. #quiet is itself a line, so its prompt went out before anything knew to stay silent; and the line after a quiet script's last one comes from the console, having already been denied one. Off by exactly one line in opposite directions. A first attempt at this remembered whether the prompt had been skipped, which worked and was a flag standing in for a structure. The monitor's assembler prints a prompt of its own, so it reads through shellReadRaw, which is the same source without one. One admission. Handing the console its prompt back when a quiet script ended was a real fix when I wrote it and stopped being one an hour later, because the restructure above means the console's own path prompts whatever the flag holds. The comment claimed it fixed something. Breaking it on purpose changed nothing, which is how that was found, and it is now a comment saying so instead of a line pretending to work. The startup fixture ends QUIET on purpose: nothing puts the flag back when the outermost script finishes, so a script ending #loud would have tested the easy half. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
|
c28826df77 |
Let a script run a script, four deep
A build script calling a setup script is the first thing anybody tries. What is saved when one script starts another is A POSITION AND NOT A BUFFER: the name, which block comes next, how many are left, and where in the block it had got to. Seventy bytes, and they sit next to each other in the data segment on purpose so that saving them is one copy. The block itself is read again on the way back, which costs one disk read per return and saves 257 bytes a level - the inner script reads its own block into the single buffer there is, so coming back means fetching the outer one's block again and landing on the byte it left. The slot is reached by stepping rather than by multiplying, because this machine has no multiply and the depth is never more than three steps. Four levels. Deep enough for a script calling a script that calls a helper, shallow enough that a script running itself says so rather than filling memory. A line that fails now stops every level and not just the innermost, because a build whose helper failed should not carry on in its caller. The caller's place is saved BEFORE the new file is looked at, and put back on every way out that is not success. Opening writes the name into the live state in order to ask the disk about it, so by the time "there is no such file" is known, the caller's place has already been overwritten - a failed 'do' inside a script would otherwise leave the script that ran it reading from a name it never chose. The test resumes in the outer script's SECOND block, which is the case the whole design turns on and the one an ordinary nesting test would miss. Breaking the re-read, the save, or the limit each fails it. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
|
a12d61fb80 |
Give the shell an echo, so a script can say what it is doing
Say.sbx has printed words since long before there were scripts, and is the wrong shape for one. It is a program: it has to be found on the disk, loaded and started, it prefixes what it was told with "it says:", and the system prints "finished" after it. Three lines of noise around one line of narration, and a load off the disk to produce them. echo is a command, so it costs a comparison. With nothing after it, a blank line - which is what anybody expects and is worth having to space a long script out. Not called "say", although that is the better word. Built-in commands are tried before the disk and always win, so a built-in say would shadow Say.sbx and quietly change what every existing script and test meant by it. Also puts "do" in the help, which the commit that added it forgot, and splits the help text: the new lines pushed it over the assembler's 255 character limit for one string. That failure was hidden for a few minutes by a 'make' whose errors were going to /dev/null - the build kept the disk it already had, and the machine cheerfully reported "I do not know: echo" from a system assembled before echo existed. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
|
2466d79d9c |
Let the shell run a file of commands
'do <file>' runs the lines in a file as though they had been typed. The
only thing a script changes is where the next line comes from: everything
below shellReadLine - splitting the line, matching it, loading a program -
cannot tell the difference and does not have to.
What makes a file a script is '#!' on the front of it, not its name and not
a flag in its entry. The rule this filesystem keeps is that an entry holds
only what the content cannot say about itself, and a script can say what it
is; the loader already refuses anything that is not SBEX, so the two kinds
of runnable file turn each other away without either knowing about the
other. It is also the deferred half of the file-typing design, which said
to wait for a second kind of runnable thing before building any of it. This
is that second kind.
'#' is a directive and ';' is a comment, as in SplitBit assembly - one rule
across the machine rather than two dialects. Not Unix's convention: there
'#!' really is a comment that only the kernel reads, while here the shell
requires it and refuses the file without it, so calling it a comment would
be a lie about what it does.
A script stops at the first line that does not work, which is what the
LineFailed groundwork was for. Comments and blank lines are dropped by the
reader rather than by the dispatch, so they are not echoed either. A script
running out hands back to the console rather than ending the shell, because
running out of file and running out of typing are not the same thing. The
interactive assembler reads through the same path, so a script can contain
a block of assembly.
Three things this cost that were not obvious:
- RET puts A and B back, so a routine cannot answer in them. scriptByte
returning the character in A assembled, ran, and handed the caller its
own A back every time. It answers in memory now.
- A last line with no newline is still a line. Text files do not reliably
end with one and an editor eating it is a bad way to find out a command
did not run.
- Not LastStatus. See the commit before this one.
Six checks in three tests, two of which are about byte positions rather
than behaviour - a command lying across the boundary between two blocks,
and that missing newline - so their fixtures are generated rather than
committed, where an editor cannot helpfully repair them.
Nesting is not in yet: a script cannot run a script. That wants a stack of
positions rather than the one the reader keeps.
Also derives native.sh's self-hosting source list from cosmos.asm's own
#Include lines. It was a hand written list and went stale the moment
script.asm existed - the fourth time a list beside a thing has drifted from
the thing - so it now asks the thing.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
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AnachronautandClaude Opus 5
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2f22807458 |
Give the demo a real tune: the Anachronaut Labs theme
The composition is the user's - a leitmotif they already have variants of, written into the note table by hand. It replaces the eight note scale that was there to prove a note could be played at all, and it is a better demo for the obvious reason and one less obvious one: it is long enough to hear whether the machine keeps time, which a run of eight notes is not. Forty five notes, 567 frames, 9.45 seconds, peaking at 19,461 of 32,767. The test budget goes to twelve million cycles, which is a duration rather than a guess: at 16,667 cycles a frame the music is 9.45 million, so there is room to add bars before anybody has to come back here. Also records what borrowing the screen's frame actually costs, which came out of writing music rather than out of theory. The frame is not too slow, it is FIXED: every duration is a whole number of 16.67 ms, so a note worth a third of a beat cannot be written, and the way round it is choosing a tempo whose subdivisions land on whole frames - making the tune fit the machine. That is the argument for the timer peripheral wanting an arbitrary tick rather than a faster fixed one, and for the screen not being the clock: a display refresh and a music routine have no reason to share a rate. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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85329f13c3 |
Take a device's line down when its status port is read
A device raises a line and something has to take it down. Two things did: being interrupted, and being woken from WAIT with the Interrupt Flag down - the second because a masked program has nowhere to dispatch to, so nobody else would. There was a third way to learn a device had finished and nothing answered it. The documented idiom reads the status, branches out if the device is already done, and only WAITs otherwise; on a disk quick enough to finish before the first look, which is every disk here, the WAIT is unreachable. The line then stood for the rest of the machine's life. The program that leaves it standing never pays for it - it was masked throughout. The bill arrives at whoever next sets the Interrupt Flag. The boot chain reads the disk to load a program, leaves the line up, and hands over; the loaded program is then interrupted on behalf of a read that finished before it existed, through a vector table with no entry for a device it never touched, and faults on the instruction after its SIF. Found by running Examples/tune.asm through Once. It set up its whole sound and died four bytes before its first note, which is why it was silent rather than wrong - and why it looked like a sound bug for a while. So reading the port that answers a device takes its line down, the same way taking the byte already took the console's down. Disk and screen do it on their status port. And a reset now clears every line, which is the sentence the manual already makes about the vector table: a handler left behind aims an interrupt into a program that is no longer running, and so does a line. testPrograms/diskLineTest.asm pins it - the racy idiom, then SIF with no handler installed anywhere. It faults without the fix. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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d388cd3122 |
Give the machine a sound device
Four channels on ports 0x40 to 0x4F, each one a whole soundThing voice:
two oscillators, two envelopes, a filter and the routing between them. A
channel keeps its patch between notes, so a program sets an instrument up
once and then plays it.
Six ports rather than forty, because a voice has around forty settings and
four of them would spend more than half the port space on one device.
There is a selector and a value instead: say which channel, say which
setting, write it. That is three writes to change a setting and two to
play a note, which is the right way round - patches are loaded, notes are
played in an inner loop.
Samples come from the machine's clock and not the host's: 48,000 a second
of emulated time, worked out in whole numbers so it never drifts. A
million cycles is exactly 48,000 samples on any host at any speed, which
is what makes a sound something a test can compare. --sound writes them
out, the way --screen writes a picture, for the same reason: the suite has
no speaker.
Tests/sound.sh is 22 checks and found three real defects the first time it
ran, all the same shape - a synthesizer written for a patch editor, wired
up as hardware and inheriting the editor's assumptions:
- Only one voice had an oscillator switched on, so three of the four
channels could not make a sound whatever was written to them.
- That voice's oscillator arrived at full gain and every other one
arrived at nothing, an asymmetry with no reason behind it.
- A note with no sustain is silent but not over, so the obvious way to
wait for a sound to finish waits for ever.
The first two are fixed by the device defining its own power-on state
rather than inheriting synthInit's: every channel arrives able to make a
sound, so writing a note number is the whole of playing a note. The third
was already written into the manual as advice, an hour before the check
existed. The check disagreed with the documentation and the check was
right; the manual now says the one rule, which is that a note sounds until
the gate is dropped.
Programs/Examples/tune.asm plays eight notes, taking its tempo from the
screen's frame interrupt because that is the only regular beat this
machine has. It spends 99.8% of its cycles asleep in WAIT.
Voyager has no speaker yet - this is the device and its tests. Playing the
samples out of the window is the next commit.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
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AnachronautandClaude Opus 5
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13b20c8834 |
Give the screen a bitmap mode
V4. Mode 2 is 320 by 200 with a byte a pixel: no tile to look up and no attribute to add, the byte IS the palette index. Programs/Examples/picture.asm fills a whole one in 127 bytes of program and 47,498 cycles. IT IS THE SAME MEMORY AS THE TILES AND THE MAP, which is what shared video memory has always been, and there is nowhere else it could be - 64,000 bytes of picture in a 65,536 byte bank leaves room for nothing beside it. Going to bitmap mode does not clear the text screen, it stops calling it one, and coming back finds the tiles holding whatever the picture put there. Taking the screen means taking it. The palette moves to 0xFC00, the top of video memory, because it is the one thing that has to mean the same in every mode and 64,000 bytes of picture leaves nowhere in the middle for it to hide. That is a documented address, so the example, the tests and the manual move with it. A BITMAP HAS NO COLUMNS AND NO ROWS, and both registers read zero rather than a leftover from the last mode. The console asks: told there is no character screen, it has nowhere to put a glyph and draws nothing, while still saying everything down the serial line. The honest alternative is what a machine with shared video memory really does, which is scribble marks nobody can read across somebody's picture - honest and useless, since a program that has taken the screen has not stopped wanting to print. Six checks in Tests/video.sh, to 55: that the mode is 320 by 200, that a byte is one pixel's colour and only that pixel, that printing leaves a picture alone while the letter still goes out, and that the columns register says nought and then forty again. The example is worth reading for one thing beyond the mode: Fill leaves its destination past what it touched, so two hundred rows are drawn from one address set once. Working out where row n begins would be n times 320, and this machine has no multiply. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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1174bd9af5 |
Give the machine a frame to wait for
V3. The screen interrupts at each frame on hardware vector 0x30, and WAIT finally has something worth sleeping on. THERE WAS NO CLOCK. Every program that wanted to happen at a certain speed counted instructions and hoped, which is why Snake's pause silently halved the day a cycle stopped being an instruction and became a memory access - the program was right and the thing it was counting changed underneath it. A screen finishing sixty times a second is a real beat, and it is counted in the MACHINE'S cycles rather than the host's, so the same program sees the same number of frames in the same number of cycles however fast anything really ran. That is what makes a frame something a test can count and a recorded result can hold. Status bit 0 goes up when a frame has gone by and reading the status port puts it down, so a program with no handler can watch for it instead. Control bit 0 asks to be interrupted, and is OFF when the machine starts: an interrupt with nothing installed to catch it is a fault, so a screen that began interrupting the moment it was switched on would take down every program written before frames existed. More than one frame can pass between two looks, and the flag and the line are each one thing, so several still mean one of each. A missed frame is missed. Programs/Examples/frames.asm prints a dot a frame for a second: 1,000,324 cycles, and 996,460 of them spent asleep. That split is the thing worth seeing - a program that polled instead would print the same sixty dots, take the same second, and spend every cycle of it on the bus. Its header explains why waiting is not spinning and why a machine with a beat can stop guessing at one. Six checks in Tests/video.sh, and two of them are about the clock rather than the output, because the output cannot tell the difference. That the machine slept through nearly all of ten frames, and that polling three frames actually took three frames - a status flag that stayed up once set would print exactly the same character and look perfectly correct. Breaking the frame interrupt on purpose left a machine asleep for ever and hung the whole suite, which is a worse way to be told than a failing check. Tests/video.sh bounds its runs at ten seconds now, the way Tests/run.sh always has. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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5732a31b2e |
Stop the allocator starting the directory again for every file in its way
Placing one file on a disk with the source tree on it cost 9.4 million cycles. It costs 1.4 million now, and assembling colours.asm went from 13.9 to 6.0 seconds. sbfsAllocate gave up the moment it found anything in the candidate's way: it moved the candidate past that one entry and STARTED THE DIRECTORY AGAIN FROM THE FIRST BLOCK. With files laid down one after another that is a restart per file, and every restart reads directory blocks off the disk until it reaches the next thing in the way - which is further in each time. Placing one file among 183 of them cost thousands of block reads. The candidate moves along DURING the pass now, and the pass carries on from where it is, so entries later in the directory are tested against where the candidate has got to. On a disk that has been appended to - which is what a disk mostly is - one pass walks it past everything and a second confirms nothing is left. Two passes rather than one per file. IT IS STILL FIRST FIT, and Tests/agree.sh is what says so: the machine and SplitDisk build the same tree and the images still match byte for byte, which they could not if allocation had started choosing differently. The argument is that the candidate only ever moves past something that genuinely overlaps it, and when it does there is nowhere below to go - the entry in the way covers everything up to its end and begins before the candidate ends. The first attempt at this was slower than what it replaced, by three times. It finished the pass and jumped to the FURTHEST overlap, which sounds better and is worse: with files laid contiguously only one entry ever overlaps, so the old early exit was the fast path and reading the whole directory to find the one thing was pure loss. The number of passes was never the thing to fix - restarting them was. The boot slot in the test fixtures goes from 32 blocks to 40, which is what a shipped disk has. Stage two is 8,231 bytes and 32 blocks is 8,192: a fixture tighter than the thing it stands in for fails on a change the real disk would have taken, and says "the boot slot is too small" rather than what actually grew. WHAT THIS DOES NOT FIX is assembling CosmOS, and that is worth saying plainly. It takes 654 million cycles on the mirrored disk and 653 million on a flat test disk with a sixth as many files, so it is not a filesystem problem at all. Cycles per byte of source climb with the size of it - 1,383 for colours.asm, about 3,000 for Edit.asm, 6,290 for cosmos.asm - which says the native assembler is superlinear in what it reads. That is a separate thing to go and look at. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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7073b972e6 |
Say what went wrong, and give the file tools room for a path
The makefile on the disk was fine. "Makefile" is not "makefile", and SBFS names are case sensitive - but neither tool said so, and both failed in ways that pointed somewhere else. MORE PRINTED A NUMBER THAT MEANT NOTHING. "cannot find the file, error 2" invents a vocabulary the system does not have: the filesystem library documents its answer as zero or not zero, never as a code, so 2 could not be looked up anywhere. It says "there is no file by that name" now, which is the only way opening fails that a person can do anything about, and is nearly always a name typed slightly wrong. EDIT SAID "0 LINES", which is also what an empty file that IS on the disk says. A name typed slightly wrong therefore looked exactly like the document you meant to open, right up until you saved it somewhere new. It says "new file" instead. Two bugs came out of writing that, and both are worth more than the feature. The first is mine and the label lied to me: loadNothing is not where a load FAILS, it is where every load FINISHES, reached at the end of splitLast on files that opened perfectly well. A flag set there on the strength of the name was set on everything. It is called loadDone now, and the failure has its own name. The second is older and general: a program is loaded once and may be run many times, so "load Edit.sbx" then "run" twice is two sessions over one copy of the Data Segment. Anything a session changes has to be put back by the session. A zero written in the Data Segment is the state a program starts in the first time and never again - and cosmosEdit runs Edit twice from one load, which is why it caught it immediately. AND THE FILE TOOLS COULD NOT ADDRESS THE TREE THEY NOW HAVE. Edit took 23 characters of name and More and Type took 29, which were right when everything lived in the root. With the sources mirrored onto the disk, "/Source/CosmOS/Assembler/classify.asm" is an ordinary thing to type - thirty-seven characters, cut down to a name meaning something else, or nothing. All of them take sixty-three now, which is what the shell reads of a command line, so nothing longer can arrive. Wander with it, since a directory is a path too. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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0852666e73 |
Mirror the source tree onto the system disk
A list of files in a makefile goes stale the moment somebody adds a program and forgets to name it, and what they forgot is invisible until they go looking for it on the machine. So SplitDisk gained a mirror command and the disk rule is one line: putting a file where the others live is now the whole of putting it on the disk. EVERY FILE GOES THROUGH put AND EVERY DIRECTORY THROUGH mkdir. That is the point of it - mirror adds a walk and no filesystem code at all, so anything the format refuses here it refuses everywhere, in the same words. What is new is the walk, and the walk is what the six checks in Tests/disk.sh are about: that it goes all the way down, that it leaves dotfiles and named directories behind, and that a name too long stops it. REFUSED RATHER THAN SKIPPED, because a disk quietly missing a file is the exact failure a mirror exists to prevent. Which meant four sources had to be renamed - a directory entry holds 22 characters and they were 23, 23, 24 and 29: 16bitSegmentedSieve.asm -> 16bitSieve.asm 16bitSegmentedSieveModern.asm -> 16bitSieveModern.asm consoleInterruptTest.asm -> consoleInterrupt.asm controllerWriteTest.asm -> controllerWrite.asm The test names in the manifest are unchanged, since those are identifiers and every recorded result is filed under them. Only where the source lives has moved. The entries are sorted before anything is written. readdir hands them back in whatever order the host filesystem feels like, and a disk image that comes out different from one run to the next is an image no test could compare against another. The disk grew from one megabyte to four and from 192 directory entries to 1,024. The sources are 2,850 blocks and the mirror filled the old directory on its first run, which is a thing that should not need thinking about again. The Tests fixture disk is deliberately NOT mirrored. It is a controlled fixture with known contents, and the shipped disk is the one meant to be useful; they want different things. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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ff4b025058 |
Make the cursor blink while the machine is waiting, and show how the palette works
THE CURSOR DID NOT BLINK, and the reason is worth stating: it blinks on the machine's clock, and the machine's clock had stopped. A console waiting on a key stops the CPU, so no cycles passed, so the phase never moved - and the one moment somebody is looking at a cursor is the moment they are being asked to type. Waiting is now charged as IDLE CYCLES, which is what they were built for: a machine stopped on a device is not using memory, the same distinction WAIT makes, arrived at from the other direction. And the devices are told as it happens rather than when the instruction finally finishes, because a display controller does not stop blinking because the processor is waiting on a keyboard, any more than a disk stops turning. A keyboard file can now say NOTHING happened. A zero is a byte no keyboard sends, so it is free to mean "a moment went by with nobody typing" - which is the commonest thing behind a window and the only thing a file otherwise could not express. That unlocked the whole waiting path: three checks that the cursor is lit, then dark half a second later, then lit again, which is what blinking is. And Programs/Examples/colours.asm, because the palette had nowhere a newcomer could read it. It prints the sixteen pairs, prints each one again turned inside out, and then CHANGES ONE by writing three bytes into the palette - so the difference between using the colours a machine wakes up with and choosing your own is visible in one program. Its header explains what a cell is, what the attribute nibble does, why palette entries are four bytes rather than three, and why video memory has to be reached through the controller. The manual now says where the palette lives and points at it. SplitLint found a redundant RSTA in the example, which was worth acting on rather than suppressing: the zero was already in A from the mode write two lines up, and saying so in a comment teaches that SETD does not touch A, which is a thing worth knowing. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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d6feddd1b6 |
Give the console colour and a cursor
COLOUR COSTS A NIBBLE AND NO HARDWARE. A glyph is drawn in palette indices 0 and 1, paper and ink, and a cell's attribute nibble adds sixteen to both - so sixteen banks is already sixteen ink and paper pairs, and all that was missing was a register saying which one the console draws in. That is port 0x06, read as well as written like the rest. The palette a machine wakes up with is arranged so that HIGHLIGHTING IS ONE BIT: banks 0 to 7 are colours on black, banks 8 to 15 are the same colours as paper with black ink. So attribute XOR 8 turns any pair inside out. That is a convention rather than a rule of the machine - the device only ever adds the nibble and looks the answer up - but it is the convention that makes a highlighted line and a cursor free. Bank 0 is still grey on black, so nothing that was written before this has changed colour. THE CURSOR IS THE SAME BIT AGAIN. It is drawn by turning its cell inside out rather than by putting a block over it, so the character underneath stays readable, which matters to somebody editing a line. The device draws it rather than the window, because on a machine with a screen a cursor is a hardware feature - one drawn by the presenter would not be in a picture the machine saved. It blinks on the machine's own clock, half a second each way, so the phase is a pure function of the cycle count and a screen saved at a given cycle is the same screen every time. A blink on the host's clock would have made every saved picture a matter of luck. Off unless asked for, with bit 2 of the control port. That is right for a machine - a program painting its own screen does not want something blinking in the middle of it - and CosmOS asks for one at boot. It also asks again when it takes the console back from a program that has stopped, because a program handing key mode back the way it was told to writes zero, which turns the cursor off. The shell owns the prompt, so the shell is what makes sure there is something blinking at it. Nine more checks in Tests/video.sh, to 41: that the attribute colours the ink and not the paper, that XOR 8 turns both, that it reads back, that a cursor appears where the registers put it and only when asked for, and that it goes dark again half a million cycles later. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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978aec4809 |
Let the console edit a line, and let a file be a keyboard
BACKSPACE REACHED THE SHELL. A terminal in line mode does not hand a program every keystroke: it collects a line, rubs out a backspace, and delivers the finished thing at Return. CosmOS has always relied on that, and behind a window there is no terminal to do it, so the raw 0x08 went into the command buffer. Correcting a typo produced a line that looked perfectly right on the screen and matched no command at all - "I do not know: help". So the console does it, because behind a window the console IS the terminal. In key mode it does not, and must not: a program in key mode asked for every keystroke as it happens. CosmOS now asks for eighty columns at boot. Its own help text is seventy-four characters wide, and dir, the monitor and the assembler's messages all assume room. The machine still wakes up in the smaller mode, which is right for a machine - it is the system that knows what shape of screen its own output needs, and a game that wants forty columns says so. AND A FILE CAN BE A KEYBOARD, which is the part that matters beyond today. The console behind a window is not the console behind a terminal, and until now the difference was unreachable: it broke twice in two days and a person typing found it both times. --keyboard installs the same hook a window does, so the same path runs, and the manifest has a column for it. cosmosTyped types "halp", backs over it, arrives at "help", and requires the help to come out. Verified by removing the rub-out, which loses the whole help text. It does not test the window. Voyager's key queue and everything about presenting frames are still out of reach. It tests the console, which is where the logic is. Along the way: VOY_OBJS was missing from the dependency include, so voyager.o never rebuilt when a header changed. EmulatorOptions grew a field, Voyager kept an object that disagreed about the size of the struct, and smashed its stack on every run. A clean build hides it and 'make sanitize' cleans first, so that would never have found it either. Tests/voyager.sh did, by failing all 115 tests that start the machine - which is the differential test earning its keep on a bug that has nothing to do with what it was built to check. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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310804e267 |
Give Snake back the speed its comment promised, and present in step with the display
Two things, one certain and one likely. THE CERTAIN ONE IS NOT THE WINDOW'S FAULT. Snake's pause loop said "at the emulated rate this is about an eighth of a second", and it was, when a cycle was one instruction. A cycle became one memory access, every loop in the machine got dearer, and this one silently doubled: the game has been running at half the speed it documents ever since, in a terminal as much as in a window. Measured rather than guessed - the inner loop is a DECA and a BNA, one byte and three, so four cycles a turn, and a whole run went from 3,848,610 cycles to 1,920,504 when the outer count came down from 256 to 122. Almost exactly half, which is what the arithmetic said it would be. That is the cost model change reaching a program nobody thought to re-measure. Worth looking for others: any loop tuned by eye before that change is running at half its intended speed. THE LIKELY ONE is the frame limiter. Without the vsync hint, Raylib sleeps towards sixty frames a second on its own clock, which beats against a display refreshing on its own - frames shown twice or skipped, and the machine handed an uneven number of cycles each time, since it takes its budget from the wall clock. The hint puts presentation in step with the screen. SetTargetFPS stays for a driver that ignores it. Snake is one byte bigger, because RSTB became INIB. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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43a05b3df1 |
Replace the escape parser with cursor registers
The console had grown an ANSI parser, and that was the wrong shape. ANSI exists because a screen used to be on the other end of a serial line and a byte stream was the only channel there was. This screen is memory the program can already address, so reaching it by sending characters for a state machine to take apart is a middleman for something the machine does better - and it meant accepting an open protocol somebody else defines, in hardware, with no natural end to it. Everything else on this machine is registers. So the console gets three: cursor row at 0x03, cursor column at 0x04, and a command port at 0x05 where 1 clears the screen. Both cursor registers are READ as well as written, which is the thing an escape cannot do without sending a query and parsing a reply - a routine that wants to put the cursor back where it found it can now ask. Clearing is one command against a thousand cells walked one at a time. Snake and Life are smaller for it: 2,168 bytes to 2,163 and 1,410 to 1,396. A HOST TERMINAL STILL SPEAKS ANSI, and bridging to the host is the emulator's job, the same job it does reading standard input. So the escapes are now GENERATED, outbound, for the set this device chooses, rather than parsed inbound as though the machine were a terminal. The set cannot grow behind our backs because we are the ones saying it. The cursor is announced lazily, at the next character rather than at the register write, so setting a row and a column costs one sequence rather than two. The console's block widens from three ports to six, which registryTest noticed: it had been asking about port 0x05 precisely BECAUSE nothing was there, and the console had just moved in. Re-blessing it would have left it checking nothing, so it asks about 0x80 instead - clear of the console, the disk, the screen, the controller, and the sound device coming to 0x40. Six checks in Tests/video.sh swapped from the sequences to the registers, including that the cursor reads back and that one sent past the edge is clamped rather than refusing. Those checks also stopped counting bytes from the ends of a file, which had quietly started measuring an escape the moment the console began announcing the cursor. SplitLint caught the one thing worth catching in the port: the clear command leaves A at 1 and key mode is also 1, so the second load looks redundant. Acting on it would tie a console command to a console mode by coincidence, and break silently if either ever moved, so it is suppressed with that reason rather than removed. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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556a14b288 |
Teach the console the sequences the corpus already speaks, and let the status port see the window
Three things Snake found the moment somebody ran it in a window, and all three are the same kind of mistake: the console grew a screen and kept asking the terminal. IT COULD NOT CLEAR THE SCREEN. Every program here that moves a cursor does it with ANSI escapes, because until there was a screen the thing on the other end was somebody's terminal. The controller drew "[2J" as three letters and left the board underneath. It now parses them, which is what a video terminal did - a VT100 is exactly this. The whole corpus uses two, ESC[2J and ESC[H, and the general shape is recognised so anything else is swallowed rather than drawn: a sequence nobody implemented should leave no marks. Cursor positioning is in too, since it is the same parse and one line more. IT DID NOT SEE KEYS FROM THE WINDOW, but did when the terminal behind it was focused, which is the whole diagnosis in one sentence. Snake polls the READY bit and never blocks, and consoleFetch - what the status port asks - was polling standard input regardless of whether a front end had installed a hook. So a window's keys were invisible to every program that looks before it reads, and a keystroke aimed at the terminal would be picked up instead. The hook now takes a question. Zero is the status port looking, and must not present or sleep: a program polling in a loop would otherwise be charged a frame for every glance. One is the data port blocking, where presenting is exactly right, because a machine waiting for a key is still a machine somebody is looking at. One value for both would have made either polling ruinous or waiting dead. AND IT RAN SLOWLY, which was the same bug wearing a hat: a game that never receives a steering key is a game that only ever goes one way. Six more checks in Tests/video.sh, to 32: that ESC[2J clears, that ESC[H goes to the corner without disturbing what is drawn, that ESC[3;5H counts rows and columns from one, and that an unknown sequence is swallowed and leaves nothing behind. The hook itself is still the one thing here the suite cannot reach - it exists only when there is a window, and this host has no display. It was found by a person playing Snake, which is where the Test Manual says these go on being found. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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6f8ad42277 |
Fill the window, let it be resized, and make black black
Three things a person looking at a real screen found in five minutes, none of which the headless tests could have seen. THE PICTURE FILLED A QUARTER OF THE WINDOW. The window opened at the largest screen the device can make, doubled, and then drew a 320 by 200 mode at that same doubling - so three quarters of it was bezel. It now takes the largest whole-number scale that fits: the two modes are exactly a factor of two apart and the window opens at twice the larger, so both fill it exactly, at four and at two. Changing mode changes how sharp the screen is rather than how big it is. Whole numbers on purpose. A 320 by 200 picture stretched by 2.7 has some rows twice as tall as their neighbours, which on eight pixel glyphs is the difference between text and mush. THE WINDOW WOULD NOT RESIZE. It does now, and the picture rescales to whatever it becomes, still in whole pixels and still centred. How big somebody wants a screen is not the machine's business. AND BLACK WAS NOT BLACK. Both the paper and the bezel were tinted towards green, on the theory that a phosphor never was neutral. On a real screen that reads as a fault rather than as character: a background that is nearly black looks like a background that failed to be black. Paper is black now and ink is a neutral grey, because a default should be the unsurprising thing - anything with a point of view about colour is 254 palette entries away and belongs to a program. The bezel is a clearly lighter grey, so what is left over when the window's shape does not match the picture's looks like a bezel rather than like more screen. The two checks that name the waking colours name the new ones. That they had to change is the check working: they say what they depend on rather than assuming it. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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773b0f8add |
Put CosmOS on the screen without changing a line of it
The console is now a display controller as well as a port: it owns a font, keeps a cursor, handles newline, carriage return, backspace and wrapping, and scrolls. That is an ordinary kind of chip - it is what a video terminal's character generator did - and it is the reason this rung needed no changes to CosmOS at all. CosmOS already writes bytes to port 0x00. It writes to BOTH the screen and standard output, which is deliberate. A machine with a screen and a serial line is an ordinary machine, the emulator's standard output is that serial line, and one console drives both. It is also what keeps all 165 recorded results passing under Voyager, and what makes --screen work on the plain SplitBit: there is one console and it drives everything it has. Scrolling moves the video device's origin and no memory. The row arriving at the bottom is cleared because the map is a ring and it holds what was there 128 rows ago; the rows going off the top are not, and that is a hundred rows of scrollback nothing had to keep. The test reads the register back rather than looking at the screen, because a console blitting rows instead would look identical and cost twelve percent of a frame for every line printed. The font is vendored from Hatchet-GPU with a note saying where it came from, since that repository is not part of this one. 135 glyphs in ASCII order, which is the thing that makes it worth keeping - PETSCII's whole inconvenience was that its order was not ASCII's, so a machine using it needed a translation table in front of every string. Here the machine subtracts 32. It is stored one bit a pixel and expanded into tile memory at reset: 1,088 bytes against 16 kilobytes. Voyager gets a keyboard. A window has no standard input, and a machine blocking on it inside a frame would stop drawing and stop answering, so a front end with a window installs a hook that the console calls while it has nothing: it keeps the window alive and hands back a key. The hook has to tell "nobody has typed yet", which happens sixty times a second, apart from "the window has gone", which is the end of input - one value for both would have made the first keystroke look like a closed machine. In line mode the console echoes what it is given, because there is no terminal behind a window to do it and that was always the terminal's job. Tests/video.sh grew from 14 checks to 26, half of them about the console rather than the device: those programs ask the video device for nothing and write bytes to port 0x00 like every SplitBit program always has. Verified by breaking two things - removing the scroll failed exactly the two checks about scrolling, and removing the cursor advance failed exactly the three that depend on it. Two video checks had quietly depended on palette entry 0 being black, which stopped being true the moment a machine woke up able to show text. They now set what they are about to look at, and a new check pins the waking state itself. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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83623a3df3 |
Give the Voyager a screen
A tile engine on ports 0x30 to 0x3F, bringing one bank of video memory registered the way the disk's buffer is. The CPU writes cell indices and the device turns them into pixels, which is the whole reason a screen is affordable at a megahertz: a frame is 16,667 cycles, a full 320 by 200 picture is 64,000 bytes, and a 40 by 25 map is 2,000. A program that changes two cells writes four bytes. The cost of a screen becomes the number of cells that changed rather than the number of pixels on it. Which makes colour depth free, so the tiles are eight bits: an 8 by 8 cell is 64 pixels and each picks independently out of 256 colours, with no per-cell limit of the kind that made a Spectrum two and C64 multicolour four. The low nibble of a cell's attribute is ADDED to every index in its tile, sixteen at a time, so a tile drawn in 0 to 15 appears in any of sixteen schemes without a second copy in tile memory - and a tile wanting all 256 leaves the nibble at zero and gets them. Neither use costs the other anything. Two decisions are arithmetic rather than taste, and both come from the machine having no multiply. A map row is a page whether the mode fills it or not, so a cell address is the row number as the high byte and the doubled column as the low byte with no arithmetic at all; otherwise every cursor move on a 40 column screen would cost a row-times-40 in software. And a palette entry is four bytes rather than three, so entry n is at n times four, a shift. THE MAP IS A RING and the Scroll register says which of its 128 rows is on top. Scrolling moves a register and no memory: blitting a 40 by 25 screen up one line is 1,920 bytes inside one bank, which is twelve percent of a frame even with the controller widened, and a program printing one page would spend six frames shuffling memory. It is now one port write - and the rows that scrolled off are still there, which is where a terminal gets scrollback it never had. The device is part of the machine rather than part of the window. It renders into a buffer that is a pure function of video memory, so the same program draws the same picture with nobody watching; Voyager puts that buffer on the glass and decides nothing. Both binaries take --screen, which saves a PPM when the machine stops, and that is what makes a screen checkable on a host with no display at all. Tests/video.sh checks fourteen named behaviours rather than comparing a recorded image, because a recorded image would say "something changed" and leave which of the palette, the tile, the attribute, the map or the scroll register broke to be found by hand. Verified by breaking three things in turn: the additive nibble failed exactly one check, the scroll origin exactly two, and moving every cell one pixel sideways exactly the four about placement. Tests/docs.sh could not count past nine, which is how a suite of ten scripts reported itself as wrong for the wrong reason. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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e3ef25e3b3 |
Split the machine from its front end, and add Voyager
The Segan Voyager is the same SplitBit with a screen and a speaker instead of a terminal, and this is the rung that makes there be two of them at all. Everything that is actually the machine - the CPU, the controller, the devices, the run loop, the reporting - moves to machine.c, and each front end brings one file of its own. emulator.c is now sixty lines of argument handling and a three line loop. The machine runs in SLICES rather than to completion, because that is the cut a window needs: run a slice, present a frame, run another. A terminal runs slices until the machine stops. Both loops are three lines, which is why the cut is there rather than anywhere else. At this stage Voyager's window is empty. There is no video device yet and inventing a temporary way to draw would mean building something to throw away. PLAIN MAKE STILL WORKS WITH NO GRAPHICS LIBRARY. Raylib is probed by compiling and linking against it rather than by looking for a file, because a header with no library behind it passes a file check and then fails at link time. Where it is missing, make says so once and builds everything else - the machine, the assembler, the disk tool, the linter and the whole suite. A project about a small understandable CPU should not need OpenGL to run its tests. That nearly broke here: make strict globs Source/Emulator/*.c, so it would have tried to compile voyager.c and failed on precisely the machines the split exists to support, and this machine has Raylib so nothing would have caught it. Tests/voyager.sh runs the WHOLE MANIFEST through Voyager and holds it to the recorded results SplitBit is held to. Not that the two look alike: that one satisfies every recording the other does, byte for byte, exit status included. It reuses run.sh, which now takes the machine from SPLITBIT_EMULATOR, rather than keeping a second copy of the runner that would drift. Voyager not being built is not a failure - it says so and passes. Verified both ways. Made Voyager print one extra line, and 114 of 165 failed: exactly the tests that run the emulator, with the 51 assemble-only and xfail cases correctly untouched. Removed the binary, and the script skipped. Built with HAVE_RAYLIB=no, and everything else still built and checked clean. --headless is taken out of the arguments in voyager.c rather than in the shared parser, which should not learn about a window only one binary has. It exists so the suite can run this binary at all: a front end that could only be exercised by a person looking at it would be a front end nothing checks. loadFile takes a const char * now, which it always should have. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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4c3eac8d9c |
Widen the memory controller's path to sixteen bits
The controller now reaches bank memory two bytes at a time, so a transfer whose source, destination and length are all even moves two bytes a cycle between banks and one within a bank - twice what each was. A 256 byte block between banks falls from 257 cycles to 129. Alignment is required all three ways because a word is read at an even address and written at an even address; an odd anything would mean shifting bytes across word boundaries to line them up, which is a different design. A misaligned transfer falls back to the byte a cycle it cost before, so nothing already written got slower. THE CPU DOES NOT CHANGE. It still sees eight bits, a Data Pointer still addresses a byte, and no instruction means anything different. This is a peripheral getting faster, which is why it is worth doing now rather than after more is built on top of it. The rule is deliberately visible rather than smoothed over: aligning a buffer costs nothing and halves what moving it costs, and a cost a program cannot see is a cost it cannot avoid. Tests/cycles.sh is new, and is the test the Test Manual has always said this kind of change would need - run.sh strips the cycle count from every recorded result, so nothing else in the suite can see any of this. It pins the RATE rather than a total: each case runs twice from programs whose instructions are identical but for the byte written to the Command port, once asking for the transfer and once for GuardOff, which costs nothing beyond the port write. The difference is the transfer and nothing else. Verified by disabling the widening, which failed exactly the three aligned cases and left the five misaligned ones passing. The Programming Manual gains a section saying what a transfer costs, which it never said at all - it only promised a transfer does not wait, which is a different claim and could be read as promising it is free. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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8fbbeb6ec9 |
Make xfail compare the diagnostic, not just the failure
The Test Manual said an xfail test records the assembler's refusal message and so catches both an error that stops being detected and a message that changes without anybody meaning it to. It did not. run.sh checked only that the assembler exited non zero, printed the first line for a person to read, and compared nothing; --bless recorded nothing for these sixteen tests at all. So an xfail passed four different ways that look identical from outside: the intended error fired, an unrelated error fired, the message changed, or the assembler fell over on its way to the point. That is the documentation describing behaviour the code does not have, which is the exact failure Tests/docs.sh exists to prevent, in the manual that argues for knowing what your evidence is worth. The diagnostic is now stripped of colour, given the same [exit N] line every other recorded result carries, and compared through check() like anything else. Sixteen results recorded; every existing one is byte for byte unchanged. Verified the way the manual asks: one diagnostic was broken on purpose, its test failed with the changed line in the diff, and its neighbour passed. Found by ChatGPT reviewing the manual. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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d6bc416698 |
Write the Test Manual, and make the suite check it
The test system had grown to seven scripts making five genuinely different kinds of claim, and nothing said which was which. A recorded transcript and a byte-for-byte comparison against a second implementation both print [ok ] and are worth wildly different amounts, so the fourth manual exists to say so: what each script can and cannot answer, why every determinism rule is there, how to add a test, and - the part written nowhere else - where the suite is blind. That last section is the reason for the document. Three buffer overruns into adjacent variables were all found by a person using the machine and none by the suite, the sanitizers cannot see them because emulated Data Memory is one legitimate host array, and there is no second opinion about the CPU at all. A document listing only strengths teaches the wrong lesson. The bullets describing each script move out of the README, so docs.sh now reads the manual for them, and five more numbers in it are settled from the source rather than trusted: the shape of the manifest, the xfail count, how many fixture disks makedisks.sh builds, how large the lint baseline is, and the tool count in either document. Each of the new checks was broken on purpose and watched to report before being kept, which is the discipline the manual itself argues for. Also drops the stale "70 instructions" from instructiontable.py's docstring. There are 72, and a number that carries no meaning is better removed than corrected. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |