Tiles and colours are written when a program loads; the map is written whenever anything moves. Sharing one 64K bank made them compete for room neither needed all of, and had a worse consequence than being cramped: a bitmap covers the whole bank, so entering bitmap mode destroyed the font. A program could not draw a picture and then say anything about it. Split, each gets a whole bank. The atlas holds the tiles and the palette, the screen holds the map or a bitmap, and a picture now costs the map and nothing else. It also leaves 48K free in the atlas, which is where the sprite table and a second page of tiles are going. No new mechanism was needed. A bank is registered by naming the port that owns it, so a device with two banks needs two ports that own memory: the base port keeps the atlas, since tiles have been at 0x0000 since there was a screen at all, and 0x3A owns the screen. The registry now answers honestly about which ports in the block bring memory, where it used to say all sixteen did. CosmOS never addresses video memory except in one place - the screen save, which walks 196 pages of it. The page number already says which bank a page is in, so screenBankFor works it out rather than keeping a second list beside screenPageFor. Grid and picture.asm register both banks; colours.asm only touches the palette and needed none of it. Tests/video.sh names the memory every write is for, because an address cannot: tile 5 and bitmap pixel 5 are both 0x0005, and a helper that guessed would be right for the tiles and silently wrong for a picture. And picture.asm gained a check, because this change broke it and nothing noticed - registering the second bank leaves DestBank pointing at it, so the palette went into the wrong one and the picture came out black. It was the only thing here found by looking rather than by a test. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
128 lines
3.1 KiB
Plaintext
128 lines
3.1 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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* b nonsense
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b <program|data|number>
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* b 9
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there is no such bank
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* load greet.sbx
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loaded, starting at 5000
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* b program
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bank 00
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* d 5000
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5000 47 00 30 00 SETD.0 3000
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5004 72 10 SWI 10
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5006 47 00 30 44 SETD.0 3044
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500A 72 10 SWI 10
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500C 47 00 30 7A SETD.0 307A
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5010 27 1F INIB 1F
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5012 72 11 SWI 11
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5014 47 00 30 5D SETD.0 305D
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* x 5000
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5000 47 00 30 00 72 10 47 00 30 44 72 10 47 00 30 7A G.0.r.G.0Dr.G.0z
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5010 27 1F 72 11 47 00 30 5D 72 10 47 00 30 7A 72 10 '.r.G.0]r.G.0zr.
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5020 47 00 30 65 72 10 20 72 12 00 00 00 00 00 00 00 G.0er. r........
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5030 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
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* b data
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bank 01
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* x 3000
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3000 61 20 70 72 6F 67 72 61 6D 2C 20 6C 6F 61 64 65 a program, loade
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3010 64 20 6F 66 66 20 61 20 64 69 73 6B 2C 20 72 75 d off a disk, ru
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3020 6E 6E 69 6E 67 20 6F 6E 20 74 68 65 20 73 79 73 nning on the sys
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3030 74 65 6D 20 74 68 61 74 20 6C 6F 61 64 65 64 20 tem that loaded
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* b 2
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bank 02
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* x 0
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0000 01 FF 00 00 00 00 00 00 01 FF 00 00 00 00 00 00 ................
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0010 03 FF 08 00 00 00 00 00 01 20 01 00 00 00 00 00 ......... ......
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0020 00 FF 00 00 00 00 00 00 00 FF 00 00 00 00 00 00 ................
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0030 00 FF 00 00 00 00 00 00 00 FF 00 00 00 00 00 00 ................
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* s 0 FF
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that bank will not be written
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* b program
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bank 00
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* s 8000 26 48 D1 00 26 0A D1 00 18 12
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* d 8000
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8000 26 48 INIA 48
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8002 D1 00 OUTA 00
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8004 26 0A INIA 0A
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8006 D1 00 OUTA 00
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8008 18 SHR
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8009 12 AND
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800A 00 ?
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800B 00 ?
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* g 8000
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H
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that byte is not an instruction, at 800A
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A 85 B 3F Q 05
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the program was stopped
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* d 8000
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8000 26 48 INIA 48
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8002 D1 00 OUTA 00
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8004 26 0A INIA 0A
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8006 D1 00 OUTA 00
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8008 18 SHR
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8009 12 AND
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800A 00 ?
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800B 00 ?
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* b data
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bank 01
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* s 8100 68 65 6C 6C 6F 2C 20 74 79 70 65 64 0A 00
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* b program
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bank 00
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* a 8200
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8200: SETD.0 8100
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8204: SWI 10
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8206: lda.2
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8208: LDD.0.1
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820B: frobnicate
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no such instruction
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820B: INIA
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that one needs a value after it
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820B: SWI 12
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820D: .
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* d 8200
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8200 47 00 81 00 SETD.0 8100
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8204 72 10 SWI 10
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8206 42 02 LDA.2
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8208 4A 00 01 LDD.0.1
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820B 72 12 SWI 12
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820D 00 ?
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820E 00 ?
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820F 00 ?
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* g 8200
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hello, typed
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finished
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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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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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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 306
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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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24 files, 1 directory
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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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