AnachronautandClaude Opus 5
588e02aff5
The memory map gave CosmOS 0x0000 through 0x1FFF of Program Memory and applications 0x2000 and above. CosmOS is 8141 bytes at the previous commit, which is fifty one bytes short of the line, and the next thing added to it went over. GOING OVER DOES NOT FAIL WHERE IT HAPPENS. Nothing enforces the division: an application says where it goes with #Base and the loader puts it there, so a CosmOS that has grown past 0x1FFF simply has the next program loaded written over the end of it. What breaks is whichever part of the shell that program happened to cover, at whatever later moment somebody uses it. It turned up here as the monitor's assemble command answering "I do not know" to valid instructions, several commands into a session, on a machine that had booted perfectly well. Both halves are doubled: applications now start at 0x4000 in Program Memory and 0x2000 in Data Memory. That is 16K of code and 8K of data for the system, against the 8775 and 2948 it uses today. Both were on the same trajectory, and moving them together means the twenty files that say #Base are edited once rather than twice. The standalone loader's loadable.asm keeps its old base: it belongs to the loader CosmOS grew out of, not to CosmOS, and its addresses answer to a different program. The unbased-segment diagnostic keeps its old base too - it exists to produce an error message that names the address, and the message is what is recorded. Tests/docs.sh now reads the two limits out of the table in the README and measures both segments against them. It reads them rather than being told them because the table is the specification, and this is the second time in this project that the thing nobody checked is the thing that rotted. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
31 lines
1.1 KiB
NASM
31 lines
1.1 KiB
NASM
; This is a basic hello world program for the SplitBit CPU.
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; We'll create a loop that outputs each byte of our string to Output 0, the text console.
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; Include the system services so we can return.
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#Include services.asm
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#Program
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#Base 0x4000 ; Change two:
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SETD hello ; Change three
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Start:
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LDA ; Load a byte of the string into A.
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BRA End ; If A is zero, branch out of the loop.
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OUTA 0x00 ; Output the value in A to Port 0, the text console.
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INCD ; Increment the Data Pointer to the next byte of the string.
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BRI Start ; Branch immediately to the start of the loop.
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End:
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INIA 0x0A ; We'll load a linefeed into A and output it to make it look nice.
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OUTA 0x00 ; Output it to the text console.
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;HALT ; Terminate the program.
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; Instead, let's call osExit to return the system nicely. Fourth change.
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SWI osExit
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#Data
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#Base 0x2000 ; Five, adjust the base of the data segment.
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hello: ; Throw a label here so we can explicitly point at this data. Six, actually.
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"Hello, World!"
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