Dialect roadmap

Which machines we could support next, and what each would cost. Tiers are effort, not hardware family: Tier 1 is a language layer over hardware a bundled core already drives, Tier 3 needs a chip emulated first, Tier 4 is blocked. Which core a machine would run on is a column, not a grouping.

src/dialects/registry.ts is the source of truth for what ships; the Shipped table below is pinned to it by dialect-roadmap.test.ts. Before planning anything, look for a shipped sibling - it is by far the cheapest shape - then follow docs/contributing/adding-a-dialect.md.

Status legend: ✅ shipped · 🔨 in progress · ⬜ planned · ⛔ blocked / needs a new emulator core.

Bundled cores

The cores are the limiting factor, so a candidate's tier is mostly a question of what its hardware needs on top of one. Their vendoring caveats - what each core does not model, and what the adapters make up for - are in Architecture.

Core	CPU	Licence	Wrapper
Z80.js (Molly Howell)	Z80 / 8080	MIT	src/emulator/z80/ - vendored; 8080 machines add src/emulator/i8080/
jsbeeb 1.13.1 (Matt Godbolt)	6502 / 65C12	GPL-3.0-or-later	src/emulator/bbc/, src/emulator/atom/
viciious (Mike Dean / luxocrates)	6510	public domain	src/emulator/c64/
6502.ts (Christian Speckner)	6502	MIT	src/emulator/6502/ - a bare CPU; each machine adds its own in-tree bus
(none - clean-room interpreter)	n/a	this project	src/dialects/<id>/interpreter/ - no core to vendor, no ROM to redistribute

Shipped

Grouped by core. Implementation detail lives in the code and in each machine's reference pages; what a row carries here is the one fact that bears on porting work, plus any gap a program can run into.

Machine	Dialect	CPU	Core	Note
Sinclair ZX81	zx81	Z80	Z80.js	Reference Z80 wiring: FAST/SLOW, NMI generator, R-register interrupt
Sinclair ZX80	zx80	Z80	Z80.js	Integer BASIC, .O images. No variable watching
ZX Spectrum 48K	zxspectrum	Z80	Z80.js	.TAP; scanline ULA contention, so raster bands hold. No floating bus
ZX Spectrum 128K / +2	zxspectrum128	Z80	Z80.js	Sibling of zxspectrum plus paging and AY. +2A/+3 not emulated
Amstrad CPC 464	cpc464	Z80	Z80.js	Gate Array, CRTC 6845, PPI and AY; .cdt tape
Amstrad CPC 664	cpc664	Z80	Z80.js	Sibling of cpc464; BASIC 1.1. Tape only - no FDC, no .dsk
Amstrad CPC 6128	cpc6128	Z80	Z80.js	Sibling of cpc464; BASIC 1.1 and 128K banking. Tape only
SAM Coupé	samcoupe	Z80	Z80.js	Four ASIC modes, SAA1099; ROM ships by permission. Discs import-only
Exidy Sorcerer	sorcerer	Z80	Z80.js	64×30 mono; the character generator is half RAM, so graphics are definable
Sony HB-10P (MSX1)	hb10p	Z80	Z80.js	TMS9918A VDP and PSG, parameterised for later MSX1s. MSX2 out of scope
MITS Altair 8800	altair8800	8080	Z80.js + i8080	No video: an 88-2SIO board and a terminal. String churn invisible to stats
Tesla PMD 85-2	pmd85	8080	Z80.js + i8080	288×256 bitmap; BASIC-G is paged in from a ROM module, not mapped
BBC Micro Model B	bbcmicro	6502	jsbeeb	Reference jsbeeb integration; CFS cassette over Kansas City FSK
BBC Master	bbcmaster	65C12	jsbeeb	Sibling of bbcmicro; BASIC IV shares BASIC II's tokens, MOS 3.20
Acorn Atom	atom	6502	jsbeeb	Own tokenizer and charset; .atm binaries. No variable watching
Commodore 64	commodore64	6510	viciious	.prg at $0801, PAL timing. No cassette audio - tape I/O not exposed
Commodore PET 4032	pet	6502	6502.ts	BASIC 4.0 via the CbmVariant seam; no video chip, screen RAM by chargen
Commodore VIC-20	vic20	6502	6502.ts	Unexpanded PAL, from-scratch VIC-I renderer; 3583 BASIC bytes free
Apple I	apple1	6502	6502.ts	WozMon + Integer BASIC; PROMs emulated as logic. No sound, no joystick
Apple II	apple2	6502	6502.ts	Integer BASIC; text, lo-res and hi-res into one raster. No Disk II
Apple II Plus	apple2plus	6502	6502.ts	Applesoft on the apple2 board. AND/OR/NOT are logical, not bitwise
Atari 800	atari800	6502	6502.ts	ANTIC, GTIA, POKEY, PIA; AltirraOS and Altirra BASIC redistribute freely
Atari 400	atari400	6502	6502.ts	Sibling of atari800; the RAM figure is the only divergence
TRS-80	trs80	-	interpreter	Level II BASIC, ROM-free; a Z80 + ROM mode waits on a user-supplied image
GE-235	ge235	-	interpreter	Dartmouth BASIC on a teletype; sibling of ge635. No debugger or watcher
GE-635	ge635	-	interpreter	Dartmouth 4th ed. on ge235's interpreter, by profile. Strings and MAT

Tier 1 - Language layer only

A bundled core, or an interpreter a shipped machine already runs on, covers the hardware, so there is no new emulator work at all: a keyword table, a charset, a memory map, an AI profile and metadata.

src/dialects/bbcmaster/ is the reference implementation - four hand-written files, everything else imported from the sibling, and the whole hardware divergence expressed as one model parameter (new BbcMachine('Master')). cpc664 and atari400 are the same shape. Point docsReference at the base dialect's page and the docs work stays nearly free. A machine name that links out has a plan under dialect-plans/ already written.

Status	Machine	BASIC	Core	Note
⬜	TRS-80 Model III / 4	Model III BASIC	interpreter	Source-compatible Level II superset, same display; no ROM question
⬜	Honeywell 6000	Dartmouth 5th ed.	interpreter	Same architecture as ge635, post-1970 DTSS; a delegation sibling of it

Tier 2 - New bus, simple display

The CPU is free and the display is a memory-mapped character grid or a plain bitmap, with no custom chip to work out first. Wire the core into an in-tree bus as pet and vic20 do, then proceed as for any dialect.

Status	Machine	BASIC	Core	Note
⬜	Compukit UK101 / OSI Superboard II	Microsoft 6502 BASIC	6502.ts	1K character display, 6850 ACIA, no video chip. Commodore BASIC's ancestor
⬜	Mattel Aquarius	Microsoft BASIC (subset)	Z80.js	40×24 text, 80×72 semigraphics; 4K RAM, so very little program space
⬜	Nascom 2	Microsoft BASIC	Z80.js	Mono character display, programmable charset; a kit machine, so no one config
⬜	Commodore CBM 8032	Commodore BASIC 4.0	6502.ts	Language free via CbmVariant, but the 80-column 6545 CRTC is new

Tier 3 - New bus, custom video or sound chip

The CPU is free but a bespoke chip must be emulated before BASIC output is visible. That chip is the gating work; once it renders a frame the rest is a normal dialect, so these promote to Tier 2 rather than shipping directly.

The Electron would be the third BBC-family variant, which is the trigger flagged in src/dialects/bbcmaster/index.ts for factoring the shared language layer into a src/dialects/bbcShared/ module.

Status	Machine	BASIC	Core	Note
⬜	Acorn Electron	BBC BASIC II	6502.ts	BBC language layer free, but jsbeeb has no Electron: needs a ULA bus
⬜	Commodore C16 / Plus/4	Commodore BASIC 3.5	6502.ts	CbmVariant extension; the TED is video, sound and timers in one chip
⬜	Oric-1 / Atmos	Oric BASIC	6502.ts	Custom ULA, and no ready-made core to borrow one from
⬜	Amstrad CPC 464plus / 6128plus / GX4000	Locomotive BASIC 1.1	Z80.js	Language free from cpc6128, but the ASIC replaces the Gate Array
⬜	Enterprise 64 / 128	IS-BASIC	Z80.js	Nick and Dave custom chips, both bespoke
⬜	Memotech MTX / Tatung Einstein / Sord M5 / Camputers Lynx	Various	Z80.js	Niche, and a bespoke video implementation each

Tier 4 - Blocked

Not a question of effort: each of these lacks something we cannot supply from the tree, or would add nothing the registry does not already cover.

Status	Machine	CPU	Why blocked
⛔	BBC Model B+ / Master Compact	6502	jsbeeb ships no such model, so the free BBC language layer has nothing to run on
⛔	Commodore PET 2001 / CBM 3032	6502	BASIC 2.0, not the shipped PET's 4.0: a new variant and ROM set for no new gain
⛔	Commodore 128	8502 + Z80	Dual CPU, the VDC beside the VIC-II, BASIC 7.0; its C64 mode adds nothing
⛔	Dragon 32 / 64, Tandy CoCo	6809	No 6809 core bundled, and none vendorable without writing one
⛔	Commodore Amiga, Atari ST	68000	No 68000 core bundled, and the machines are far past the BASIC-in-ROM era

Pre-microcomputer targets

Machines older than the microcomputer have no core to reuse and no prospect of one being vendored, so they ship as clean-room interpreters on the TRS-80's pattern. The first of a family pays for the interpreter; the rest share it through a machine profile rather than forking it, which is how the GE-635 shipped - src/emulator/dartmouth/ is parameterised by a DartmouthProfile and the second machine supplied one - and why the Honeywell 6000 now sits in Tier 1 above as a delegation sibling of it.

Adding the GE-235 widened the era bound in src/dialects/registry.test.ts to 1960-1995; widening it again belongs in the plan for the machine that needs it, not in a passing test edit.

The GE-265 is not a machine to add. It is GE's name for the pair the shipped ge235 already models - a GE-235 with a DATANET-30 front end handling the terminals - sold as the GE Mark I service from 1965. So a GE-265 row here would be the GE-235 twice. The Dartmouth BASIC that ran on that pair is the one ge235 implements; every edition from the third on was written for the GE-635, which the fourth edition's own manual says of itself ("the current implementation on a GE-635 time-sharing system", section 2.9) and which its sample sessions date to October 1967. Phase II replaced Phase I at Dartmouth on 1 April 1969.

Acorn Atom language gaps

Genuine Atom BASIC features the shipped atom tokenizer does not cover, so they are absent from src/reference/atom.ts too:

• the memory indirection operators ? (byte), ! (4-byte word) and $ (string) - the Atom's idiomatic replacement for PEEK/POKE;
• the remainder operator % and the bitwise & (AND), \ (OR) and : (XOR);
• LEN, COUNT, PTR, BGET/BPUT, EXT, FIN/FOUT and SGET/SPUT.

How a machine gets promoted a tier

1. Tier 1 → shipped: clone src/dialects/bbcmaster/. Import charset, keywords, tokenizer, detokenizer, language, keyboard, samples and targets from the base dialect; own only the memory map, memory blocks, AI profile and metadata; express the hardware delta as a model parameter.
2. Tier 2 → shipped: follow docs/contributing/adding-a-dialect.md. The work is the tokenizer, the image format and the video snapshot over a new in-tree bus.
3. Tier 3 → Tier 2: emulate the video (and sound) chip first. Nothing else can be verified until it renders a frame.
4. Tier 4 → any tier: vendor or write the missing core, or contribute the missing model upstream, then proceed as above.

Move the machine's row into the Shipped table as it registers - the roadmap test fails while a registered dialect is still sitting in a tier.