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Double CosmOS's half of the machine, and check that it fits

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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
This commit is contained in:
Anachronaut
2026-08-24 22:21:02 -04:00
co-authored by Claude Opus 5
parent 36a1b07b5b
commit 588e02aff5
41 changed files with 126 additions and 86 deletions
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Programs/CosmOS/README.md
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@@ -322,8 +322,16 @@ CosmOS divides the two SplitBit address spaces by convention:
| Memory | CosmOS | Loaded application |
| -- | -- | -- |
| Program Memory | `0x0000` through `0x1FFF` | `0x2000` and above |
| Data Memory | `0x0000` through `0x0FFF` | `0x1000` and above |
| Program Memory | `0x0000` through `0x3FFF` | `0x4000` and above |
| Data Memory | `0x0000` through `0x3FFF` | `0x2000` and above |
Both of CosmOS's halves were doubled once it outgrew the first ones. **The division is a
convention and nothing enforced it**, so CosmOS quietly grew past `0x1FFF` and the next
program loaded landed on top of its own code - which does not fail where it happens, it
fails later, in whatever part of the shell the program happened to cover. `make test` now
measures both segments against the numbers in this table, so the table is checked rather
than merely written down.
Applications state their actual Program and Data addresses with `#Base`. The SplitBit
assembler then writes an SBEX loadable image containing those addresses, the entry point,