The console's attribute has always meant something to the screen and nothing to the serial line: its low nibble picks one of sixteen ink and paper pairs, and only videoPutCell ever read it. So the fault screen's red was red in the window and grey down the wire, and Examples/colours printed " ordinary highlighted " with nothing to tell them apart. It is said in ANSI now, on the same terms the cursor is said in: a register write only marks it and the next character sends it, so setting a scheme and printing nothing says nothing, and setting the same scheme twice costs one sequence rather than two. Only the scheme nibble crosses - the page bits say which tiles a cell draws from, which is a fact about the screen's own art. THE ORDER WAS ALREADY RIGHT, which is worth saying because it looks like a borrowing and is not. Both sets enumerate a three-bit colour, red green blue counted in binary: one is red in both, three is yellow in both, six is cyan in both. The same arithmetic done twice, forty years apart. The one place they differ is slot 0, and that difference is forced - this screen is ink on black, so ink cannot be black, and slot 0 is grey where ANSI's is black. Every sequence begins with a reset, so going from bank 8 to bank 1 does not write red on the grey paper bank 8 left behind. Scheme 0 is a bare reset rather than grey on black, and a terminal is assumed to start plain - so a machine that never asks for a colour says nothing at all, and one that does put the terminal back on its way out. Two ways out, because the two endings have different rules: stopping on purpose goes through stdio, since atexit runs BEFORE the buffer is flushed and a reset written to the file descriptor would arrive in front of the text it is meant to follow. Dying on a signal writes the four bytes directly and accepts that the buffer may be lost. colourTest walks all sixteen and then halts WITH ONE STILL SET, so the recording shows the reset after the halt line rather than before it. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
59 lines
1.4 KiB
Plaintext
59 lines
1.4 KiB
Plaintext
CosmOS
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> monitor
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x examine, d disassemble, a assemble, s set, b bank, g go, exit leaves
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* Say hello from the monitor
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it says: hello from the monitor
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finished
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* Crash opcode
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[0;31mthat byte is not an instruction, at 5081
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A 00 B 0F Q 00
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[0mthe program was stopped
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* nonsense
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I do not know: nonsense
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* b program
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bank 00
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* exit
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> dir
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greet.sbx 211
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hello.sbx 53
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Life.sbx 1396
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Snake.sbx 2164
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Keys.sbx 664
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Say.sbx 156
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Where.sbx 827
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Break.sbx 149
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Grid.sbx 571
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Press.sbx 872
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Mode.sbx 48
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Flip.sbx 173
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Sprite.sbx 442
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Depth.sbx 672
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Packages <dir>
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Pad.sbx 264
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Crash.sbx 632
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vars.script 50
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blocks.script 343
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loops.script 272
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tune.sbx 318
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Play.sbx 2526
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notes.txt 21
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Apps <dir>
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hi.script 121
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bad.script 45
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plain.script 24
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cross.script 280
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nonl.script 38
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outer.script 376
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inner.script 44
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loop.script 35
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hush.script 42
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aloud.script 59
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args.script 64
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pass.script 20
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holds.script 87
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35 files, 2 directories
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> exit
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halted
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Execution halted.
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[exit 0]
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