Folders and files
| Name | Name | Last commit date | ||
|---|---|---|---|---|
This repository preserves the Sinclair ZX Spectrum micro-PROLOG distribution and contains a literate resurrection of its Z80 interpreter source.
The maintained source is under src/. It is split into thirteen architecture-oriented modules and assembles to the exact original 14,200-byte interpreter image.
- Python 3
- GNU Make
- either z80asm or pasmo
On Debian or Ubuntu:
sudo apt install python3 make z80asm pasmoOnly one assembler is required for a normal build. From the repository root:
makeThe build automatically selects z80asm first, then pasmo. The results are:
build/pcode.bin byte-exact interpreter image
build/micro-PROLOG.tap complete loadable distribution tape
Select an assembler explicitly when needed:
make build-z80asm
make build-pasmo
# or:
make ASSEMBLER=pasmoTo build with both assemblers, compare their outputs, verify the known SHA-256, and confirm that the reconstructed TAP is byte-for-byte identical to tapes/micro-PROLOG.tap:
make verifyRemove generated files with:
make cleanNo external TAP utility is needed. tools/build.py assembles the interpreter, replaces its block in the preserved distribution tape, recalculates the TAP checksum, and verifies the final file.
Interpreter address: 0x6000–0x9777
Interpreter size: 14,200 bytes
Interpreter SHA-256: 35cb4bde74ddbfe75875bdfa339e18a7fdf320526f31d2dbcb0862271b5b7174
Distribution TAP size: 53,266 bytes
Distribution TAP SHA-256: a9908f53eaecc51144e9f059833e7e55f5c7e06ca3c3c512833bf409b4de0d86
| Module | Original range | Responsibility |
|---|---|---|
| 00_definitions.asm | no bytes | ROM, tags, workspace and structure definitions |
| 01_boot_and_executor.asm | 6000–6311 | cold start, supervisor restart and evaluator |
| 02_clause_unification_and_allocation.asm | 6312–6712 | clause selection, frames, unification, trail and allocation |
| 03_garbage_collector.asm | 6713–6992 | non-moving mark-and-collect garbage collector |
| 04_term_io_and_parser.asm | 6993–710C | term output, tokenizer and parser |
| 05_lexical_tables.asm | 710D–7224 | lexical classifications and variable alphabet |
| 06_devices_and_line_editor.asm | 7225–7588 | devices, console callbacks, RFILL and line editor |
| 07_type_predicates.asm | 7589–7662 | type predicates, FAIL and NEW |
| 08_modules_dictionary_and_database.asm | 7663–7FF4 | cut, modules, dictionaries and relation database |
| 09_graphics_and_machine_io.asm | 7FF5–83AB | graphics, sound, keyboard, display and ports |
| 10_supervisor_programs.asm | 83AC–8B14 | permanent compiled micro-PROLOG supervisor |
| 11_arithmetic.asm | 8B15–9477 | reversible arithmetic and decimal engine |
| 12_cassette_file_system.asm | 9478–9777 | cassette file buffering and block I/O |
The source uses descriptive global names for callable routines and permanent objects, and dot-prefixed local labels for internal control flow. Extensive comments, pseudocode, and worked examples explain the logical execution core, including clause retry, unification, trailing, cut, and garbage collection.
The repository also retains the original historical assets:
- tapes/ — TAP and TZX distribution images;
- tape-raw/ and blocks/ — individual library records;
- snapshots/ — prepared emulator snapshots;
- utilities/ — extracted micro-PROLOG utility programs;
- cpm/ — CP/M disk image;
- Reference Manual.md — programmer's reference manual.
micro-PROLOG is a compact logic-programming system developed for early microcomputers and marketed by Logic Programming Associates. The ZX Spectrum edition combines an assembler interpreter with a library of optional programs such as SIMPLE, MICRO, EDITOR, TRACE, and MODULES.
Useful historical references:
- ZX Spectrum micro-PROLOG Programmer's Reference Manual
- Spectrum micro-PROLOG manual
- The Purple Planet: Micro-PROLOG for the Spectrum 48K
The historical root source was produced with:
z80dasm -a -t -l -g 24576 -b blocks.txt prolog.bin > prolog.asmThe maintained src/ tree is the subsequent byte-exact semantic reconstruction, not a fresh linear disassembly.