Damien Guard damieng

🏠

Working from home

// Software engineer @mongodb // Typography, keyboards, dad, C# & 8/16-bit fan. ❤☮ // Engineered previously @auth0 @github @microsoft @xbox @Netflix

damieng / basic-language.ts

Last active May 7, 2026 08:43

Generic BASIC syntax support for Shiki

	export default {
	name: "basic",
	scopeName: "source.basic",
	aliases: ["sinclair-basic", "bbc-basic", "zx-basic"],
	extensions: [".bas", ".bbc"],
	patterns: [
	{ include: "#line-number" },
	{ include: "#comment" },
	{ include: "#string" },
	{ include: "#sigil-builtin" },

damieng / z80-assembly.ts

Created May 7, 2026 06:28

Z80 assembly syntax highlighting for Shiki

damieng / z80lint.py

Created April 17, 2026 15:14

Z80 linter

	#!/usr/bin/env python3
	"""
	z80lint.py -- Z80 assembler linter for CP/M 3.1 / ZX Spectrum +3 project.

	Proper instruction parser with effects table, replacing the old regex linter.

	Checks:
	1. Stack balance: every RET must be reached with net push/pop depth of zero.
	2. Register clobber: reads of registers known clobbered by a preceding CALL
	without intervening restore.

damieng / VTX500.bas

Created April 10, 2026 19:14

VTX5000 Firmware BASIC

	10 REM [7F] 1983 Scicon Ltd V3.1 RT/DS
	80 GO SUB 9600: CLEAR ix-1850: GO SUB 9600: LET o=0: LET l=1: DIM a$(22): DIM b$(600): POKE 23609,50: LET b$(l TO l+l)=CHR$ o+CHR$ o
	100 LET dm=9100: LET cl=9000: LET mc=9300: LET er=9050: LET gk=9400: LET tx=9500: LET mm=800: LET E$="": LET I$="": LET s$="c": FOR i=l TO 22: LET a$(i)=CHR$ 10: NEXT i
	330 LET mf=ix+6: LET exc=ix+11: LET fmod=ix+45: LET id=ix+55: LET t=ix-PEEK ix-PEEK (ix+2)-256*(PEEK (ix+l)+PEEK (ix+3))
	340 FOR i=o TO 9: LET I$=I$+CHR$ PEEK (id+i): NEXT i
	350 LET ls=l: LET E$="Download Failure": IF PEEK exc=o THEN LET E$="": LET ls=o: GO TO 400
	360 IF PEEK exc=7 THEN LET E$=""
	400 PAPER l: BORDER o: INK 7: IF PEEK exc=8 THEN GO TO 2000
	410 LET T$="": GO SUB tx
	800 LET mn=o: GO SUB dm: GO TO mc

damieng / vtx5000.asm

Last active May 7, 2026 09:48

Annotated VTX5000 ROM disassembly

	; =============================================================================
	; VTX5000 Prestel/Viewdata Modem ROM - Annotated Disassembly
	; =============================================================================
	;
	; ROM: vtx5000-3-1.rom (8192 bytes, $0000-$1FFF)
	; Hardware: Prism VTX5000 Modem for the ZX Spectrum 48K
	; Developer: Scicon Ltd, 1983
	; Version: 3.1 (RT/DS)
	;
	; HARDWARE OVERVIEW:

damieng / plus3ramtest.asm

Created February 23, 2026 07:06

Full 64KB banked memory test for the Spectrum +3

	DEVICE ZXSPECTRUM128
	ORG $4800 ; Bank 5 (display bank)

	; ---------------------------------------------------------
	; All-RAM mode 0 ($1FFD=01): Banks 0,1,2,3 at $0000/$4000/$8000/$C000.
	;
	; Strategy:
	; • Bootstrap runs in Bank 5. Prints title/banks to display.
	; ULA always reads Bank 5, so display is visible throughout the test.
	; • Copies this code to Bank 1 (via $7FFD paging), then enables All-RAM.

damieng / claude-statusline.js

Created February 19, 2026 11:01

Node port of the bash status line for claude at https://github.com/ykdojo/claude-code-tips/blob/main/scripts/context-bar.sh

	#!/usr/bin/env node
	const { execSync } = require('child_process');
	const fs = require('fs');
	const path = require('path');

	let input = '';
	process.stdin.on('data', chunk => input += chunk);
	process.stdin.on('end', () => {
	const data = JSON.parse(input);

damieng / ts-parse-examples.py

Last active February 16, 2026 16:48

Tree-Sitter Example Parser

	import glob
	import subprocess
	import os
	import shutil
	import re
	import sys
	import argparse
	from concurrent.futures import ProcessPoolExecutor, as_completed
	from ruamel.yaml import YAML

damieng / ym2aytap.py

Created February 10, 2026 21:06

Convert Atari ST YM files to ZX Spectrum TAP files

	#!/usr/bin/env python3
	"""
	ym2aytap.py - Convert YM music files to ZX Spectrum .tap for AY playback.

	Reads YM2/YM3/YM5/YM6 files (LHA compressed or raw) and generates a .tap
	with a compact Z80 player that writes AY registers at 50Hz using HALT.

	14 bytes/frame × 50Hz = 700 bytes/sec → 46s (48K) or ~2:40 (128K).

	Damien Guard, MIT License, 2026

damieng / linctoch8.cs

Last active December 7, 2025 12:45

Convert LINC manual charset octets to Speccy CH8 file

	using System.Collections.Generic;
	using var outFile = File.OpenWrite("linc.ch8");

	for (var x = 32; x < 128; x++)
	{
	byte[] c = [0, 0, 0, 0, 0, 0, 0, 0];

	if (CharacterPatterns.Patterns.TryGetValue(Convert.ToChar(x), out var pattern))
	{
	c = CharacterPatterns.MapPatternToRaw(pattern);