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Say "boot image" where that is what is meant

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"Binary" was doing three jobs. It meant an SPBT file that the machine starts
from; it meant whatever the assembler happened to produce, which is now
either that or a loadable program; and it meant a compiled host tool. A word
that means three things means none of them, and the first of the three has a
name already - this project has been calling them boot images for a while
and the manuals had not caught up.

  Where it means an SPBT file       -> boot image
  Where it means either output      -> output
  Where it means a host executable  -> left alone
  Where it means base two           -> left alone

The user facing messages move with it:

  Error: No boot image specified.
  Usage: ./SplitBit [OPTIONS] <boot image>
  Error: This is not a SplitBit boot image.
  Error: This boot image is in format version 2, and this emulator reads 1.
  Successfully wrote SplitBit boot image to "hello.bin".

The assembler's own help was the interesting case. Its -o writes either
format, so "the binary" there was never right - it is "the output" now, and
the message that names the format is the one that says which it wrote.

No recorded output contained the word, so nothing needed re-blessing.
Checked before starting rather than after.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
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Anachronaut
2026-08-21 14:50:03 -04:00
co-authored by Claude Opus 5
parent 306b4dce92
commit b6004bdcde
12 changed files with 41 additions and 40 deletions
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README.md
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SplitBit is an 8 bit computer that does not exist: a CPU with its own instruction set, split Program and Data memories, an interrupt and vector system, a bus that programs can enumerate, a memory controller that can write code into memory, and a disk. This repository is a C implementation of the machine, an assembler for it, a tool for its disks, and the software that runs on it, which now includes an operating system and an assembler written in SplitBit's own assembly language.
**SplitBit assembles SplitBit.** `Programs/CosmOS/Assembler/` runs on the machine, reads source off a SplitBit disk, and writes a binary back to it with no host involved. It builds the operating system it is running under, and it builds itself, both byte for byte identical to what the C assembler produces from the same source. The test suite then boots the CosmOS that CosmOS built and has *that* one assemble CosmOS again, and the second generation is identical to the first, so the machinery has been through itself. After that the host is a convenience rather than a necessity.
**SplitBit assembles SplitBit.** `Programs/CosmOS/Assembler/` runs on the machine, reads source off a SplitBit disk, and writes a boot image or a loadable program back to it with no host involved. It builds the operating system it is running under, and it builds itself, both byte for byte identical to what the C assembler produces from the same source. The test suite then boots the CosmOS that CosmOS built and has *that* one assemble CosmOS again, and the second generation is identical to the first, so the machinery has been through itself. After that the host is a convenience rather than a necessity.
```
> load Asm.sbx
@@ -74,7 +74,7 @@ Then `dir` to see what is there, `load Snake.sbx` and `run` to play something, o
## Running Programs: SplitBit
```
./SplitBit [options] [binary file]
./SplitBit [options] [boot image]
```
| Option | What it does |
@@ -96,12 +96,12 @@ If the CPU reads a byte that is not an instruction, it goes to the fault handler
| Option | What it does |
| --- | --- |
| `-o <file>` | Write the binary to this path. |
| `-o <file>` | Write the output to this path. |
| `-I <dir>` | Look in this directory for included files. May be given more than once. |
| `-M <file>` | Write out which source files the binary depends on, as a make rule. |
| `-M <file>` | Write out which source files the output depends on, as a make rule. |
| `-h`, `--help` | Show help and usage information. |
Without `-o` the binary takes the source file's name with a `.bin` extension, in the directory you called the assembler from. Included files are looked for beside the file that includes them, and then along the directories given with `-I`.
Without `-o` the output takes the source file's name with a `.bin` extension, in the directory you called the assembler from. Included files are looked for beside the file that includes them, and then along the directories given with `-I`.
## Managing Disks: SplitDisk
@@ -123,7 +123,7 @@ Files are laid down contiguously, so a disk can have free blocks without having
## Building Programs With Make:
The assembler is built to work with make. `-o` puts the binary where the build system wants it, and `-M` writes out which libraries went into it, so that editing a library reassembles everything that includes it.
The assembler is built to work with make. `-o` puts the output where the build system wants it, and `-M` writes out which libraries went into it, so that editing a library reassembles everything that includes it.
`Programs/makefile` does this for the programs in this repository: