assembler/

p8xasm.py — the P8X two-pass assembler.

It shares its opcode table with the microcode generator: mnemonics and encodings come straight from genucode.OPC, so the assembler and the hardware can never disagree about what an opcode means. (Edit the instruction set in ../microcode/genucode.py, not here.)

Usage

python3 p8xasm.py src.asm [-o out.bin] [-l listing.txt] [--base ADDR] [-D NAME=VAL ...]

• No --base → an 8 KB ROM image (origin $0000, $0000–$1FFF), ready for the memory-card EEPROM. This is how the monitor (program ROM) is built.
• --base A → a RAM-resident blob: labels resolve to run address A, and only the A..high bytes are emitted. This is how P8X/OS and disk BASIC are assembled to load somewhere other than $0000.
• -D NAME=VAL → define an assembly-time symbol (used to parameterize BASIC via BASORG/BASRAM, for example).
• -l → write a listing file (address + bytes + source per line).

Directives

• .org, .byte, .word, .fill, .ascii, .asciiz, .equ
• .include "file" → splice another source file at this point (recursively; path resolved relative to the including file; cycles are an error). Lets sources share a committed equates file — e.g. the generated memmap.inc — so a memory-map constant lives in one place instead of being copied into firmware, the OS, and p8xcc.

Notes

• Two passes: pass 1 builds the symbol table, pass 2 emits bytes.
• ; starts a comment even inside a quoted string — avoid ; in .ascii strings.

See GLOSSARY.md for mnemonics and the programmer's guide for the full instruction set.