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
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
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
The disk's status has always had a bit meaning "still going", and the header
beside it has always said to honour it. Nothing did, because nothing could: the
host finished the transfer inside the instruction that asked for it, so the bit
could never be seen up and asking about it was asking about something that
cannot happen.
--disk-cycles gives it a latency. The command is still checked at once, because
a refusal is not work - a block that is not there fails before any head moves -
but the transfer is remembered and done when the machine has run that far. Until
then the buffer holds the block BEFORE this one.
That last part is the point. A program that does not wait gets the wrong bytes
rather than an error, which is the failure the bit exists to prevent and the one
that would never have shown up. With a latency of two thousand, CosmOS could not
even mount: sbfsMount reads block zero and looks straight at the buffer.
deviceTick is the general shape rather than a disk feature. Called once per
instruction with the machine's clock, it lets anything whose moment has come
finish - which is what a display that refreshes, or a port that waits on the
host, would want in exactly the same way.
The filesystem watches the bit now, in one small routine reached with RCAL. That
is not decoration: what it hands back is the settled status in A, and CALL puts A
back the way it found it, so an ordinary call cannot carry the one thing this
exists to carry. Two bytes of Stack rather than ten, in a routine that runs on
every block the machine ever touches - the first place in the system where the
new call is the right one rather than merely a cheaper one.
The manifest takes a @N after a disk, the way it already takes :ro, so a test can
ask for a slow one. cosmosSlowDisk lists a directory at two thousand cycles a
block and gets the same listing as everything else, which is the whole assertion:
a filesystem that did not wait would print nonsense rather than fail.
Zero is the default and every other test runs at it. What waiting costs, on a
directory heavy run: 229k cycles at zero, 275k at five hundred, 415k at two
thousand, 1.16M at ten thousand.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
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