AnachronautandClaude Opus 5
ec56439d9a
The assembler's buffers start at 0x8000, and the reason written beside them is that everything above its own data is free. That was true when it was written. The system kept below 0x1000 then; its data now reaches 0x1FFF, and the assembler's own moved from 0x1000 to 0x2000 with it when both halves of the memory map were doubled. The floor came up and the map stayed where it was, leaving sixteen kilobytes between the two that nothing touched at all. Starting at 0x4000 takes that back, with nearly four kilobytes of slack still in front of it and room for the assembler's own data to double before the two would meet. All of it went to the output image, because that is the buffer that is actually full. cosmos.bin is 13,245 bytes against the 13,312 it had, which is sixty seven bytes - the next thing added to the system would have made the machine unable to build it, and it would have shown up as a test going red rather than as anything explicable at the machine. The label table has room yet, so this is not the moment to share the space out evenly. This is the third time a limit here has gone unnoticed until something hit it, and the second where the cause was a number that stopped being true rather than one that was ever wrong. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
67 lines
3.3 KiB
NASM
67 lines
3.3 KiB
NASM
; Where the assembler's big buffers live.
|
|
;
|
|
; A map rather than a set of declarations, and it has a file of its own because the reader
|
|
; and the label table both need addresses out of it while neither includes the other.
|
|
;
|
|
#Data
|
|
|
|
; NOT #Reserve, AND THAT IS THE WHOLE POINT. Reserved space in a segment is written into
|
|
; the file as zeroes and copied at load, so 22K of scratch made a 34K file - and a loaded
|
|
; program is staged at 0x8000 before being put in place, which leaves exactly 32,768 bytes
|
|
; for the whole of it. The assembler could not load itself.
|
|
;
|
|
; None of this is initialised data. It is scratch, wanted only while the assembler is
|
|
; running, and while it is running everything above its own data is free: the system keeps
|
|
; below 0x1000, the staging area is only in use during a load, and the Stack comes down
|
|
; from the top. So the addresses are written down here and the file carries none of it.
|
|
;
|
|
; 0x4000 3072 the label index, 768 entries of four
|
|
; 0x4C00 8192 the label names, packed end to end
|
|
; 0x6C00 29696 the output file being built
|
|
; 0xE000 1792 the vector names, 64 entries of twenty eight
|
|
; 0xE700 2048 the reader's stack, six levels of 301
|
|
; 0xEF00 368 which files have been included, sixteen names of 23
|
|
;
|
|
; IT USED TO START AT 0x8000, and the reason given was that everything above the
|
|
; assembler's own data is free. That was true when it was written and stopped being true
|
|
; without anything noticing: the system kept below 0x1000 then, and its data now reaches
|
|
; 0x1FFF, and the assembler's own moved from 0x1000 to 0x2000 with it. The floor came up
|
|
; and the map stayed where it was, leaving sixteen kilobytes between the two that nothing
|
|
; touched.
|
|
;
|
|
; Starting at 0x4000 takes that back. The assembler's data is 4,114 bytes from 0x2000, so
|
|
; there is still nearly four kilobytes of slack in front of this - and room for its data to
|
|
; double before the two would meet.
|
|
;
|
|
; ALL SIXTEEN OF THOSE KILOBYTES WENT TO THE OUTPUT, which was the buffer that was actually
|
|
; full: cosmos.bin is 13,245 bytes against the 13,312 it used to have, which is sixty seven
|
|
; bytes, and the next thing added to the system would have made the machine unable to build
|
|
; it. That is a wall the label table is not yet against, so this is not the place to start
|
|
; sharing the room out evenly.
|
|
;
|
|
; That ends at 0xF070, with the Stack coming down from 0xFFFF above it - nearly four
|
|
; kilobytes, against the tens of bytes of CALL frames this ever nests.
|
|
;
|
|
; The reader's levels went from 293 to 301 when an include gained somewhere to be looked
|
|
; for: the name in each level is a PATH now, and "/Lib/" is five characters of it. Six
|
|
; levels of 301 is 1806, so the room here has to stay above that - which is why the include
|
|
; list moved up rather than the stack simply being asked to fit.
|
|
;
|
|
; THE TWO THINGS THAT DECIDE THESE SIZES are the largest program it will be asked to build
|
|
; and the largest one it will be asked to read. CosmOS is 475 labels and 9,564 bytes of
|
|
; output; the assembler itself is 555 labels, about 6,800 bytes of name and 11,648 of output. The
|
|
; second is bigger than the first, which is worth knowing: the hardest thing this assembles
|
|
; is not the operating system, it is itself.
|
|
ScratchLabIndex:
|
|
0x40 0x00
|
|
ScratchLabArena:
|
|
0x4C 0x00
|
|
ScratchImage:
|
|
0x6C 0x00
|
|
ScratchVecNames:
|
|
0xE0 0x00
|
|
ScratchSrcStack:
|
|
0xE7 0x00
|
|
ScratchIncNames:
|
|
0xEF 0x00
|