71ff44828d
New Makefile.dos16 builds with OpenWatcom wcc (16-bit, MEDIUM model) producing a standard MZ executable that runs on any DOS without DOS/4GW. All 24 source files compile clean; tested on FreeDOS 1.4 via QEMU. Changes for 16-bit compatibility: - hal_dos.c: INTX macro selects int86() vs int386() based on _M_I86 - sound.c: reduce stack buffer from 8192 to 512 samples on 16-bit - tui.c: gracefully disable TUI if screen buffer allocation fails (near heap exhaustion common on 16-bit), batch mode still works - .gitignore: add .obj/.exe/.err/.lib for OpenWatcom build artifacts Size comparison: - 32-bit DOS/4GW: 175KB + 265KB extender = 440KB total - 16-bit real-mode: 127KB standalone The 32-bit build (Makefile.dos) and Linux build are unaffected. 72/72 interpreter tests pass.
GW-BASIC 2026
A portable C reimplementation of Microsoft GW-BASIC, using the original 8088 assembly source (released by Microsoft in 2020) as the authoritative reference.
This is not a transpilation -- it reimplements the algorithms in clean C11 with modern data structures while targeting bug-compatible behavior.
Building
cmake -B build && cmake --build build
Requires a C11 compiler and CMake 3.10+. PulseAudio (libpulse-simple)
is optional -- detected at build time for SOUND/BEEP/PLAY support.
Builds three targets:
gwbasic-- the interpretergwbasic-compile-- the ahead-of-time compilerlibgwrt.a-- runtime library for compiled programs
Usage
Interactive mode launches the authentic GW-BASIC full-screen editor:
$ ./gwbasic
GW-BASIC 2026 0.16.0
(C) Eremey Valetov 2026. MIT License.
Based on Microsoft GW-BASIC assembly source.
Ok
PRINT 2+2
4
Ok
Run a program file (ASCII or binary tokenized):
./gwbasic tests/programs/prime_sieve.bas
Compile to a native executable:
./gwbasic-compile tests/programs/fibonacci.bas -c --runtime .
Ahead-of-Time Compiler
gwbasic-compile translates BASIC programs to C source, then invokes GCC
to produce native executables linked against libgwrt.a.
Pipeline: .bas → tokenizer → analysis → C codegen → gcc → native binary.
69 of 69 eligible test programs compile and produce correct output (100%).
# Generate C source
./gwbasic-compile myprog.bas -o myprog.c
# Compile to executable (automatic)
./gwbasic-compile myprog.bas -c --runtime /path/to/gw-basic-2026
Jupyter Kernel
A Jupyter notebook kernel for GW-BASIC with inline Sixel graphics rendering, INPUT support, and Pygments syntax highlighting.
pip install -e .
gwbasickernel-install --user
jupyter notebook # select "GW-BASIC 2026" kernel
What Works
100% token coverage -- all 144 GW-BASIC tokens are implemented.
Data types: INTEGER (%), SINGLE (!), DOUBLE (#), STRING ($)
Operators: + - * / ^ \ MOD AND OR XOR EQV IMP NOT < = > <= >= <>
Statements:
| Category | Statements |
|---|---|
| Output | PRINT, LPRINT, LLIST, PRINT USING, WRITE, CLS |
| Variables | LET, DIM, ERASE, SWAP, DEFINT/SNG/DBL/STR |
| Control flow | GOTO, GOSUB/RETURN, FOR/NEXT, IF/THEN/ELSE, WHILE/WEND, ON...GOTO/GOSUB |
| Input | INPUT, LINE INPUT, DATA/READ/RESTORE, INKEY$ |
| Program | RUN, CONT, STOP, END, NEW, LIST, CLEAR, AUTO, RENUM, DELETE, EDIT |
| Sequential I/O | OPEN, CLOSE, PRINT#, WRITE#, INPUT#, LINE INPUT# |
| Random-access I/O | FIELD, LSET, RSET, PUT, GET, CVI/CVS/CVD, MKI$/MKS$/MKD$ |
| Program I/O | SAVE (binary/ASCII), LOAD (auto-detects), MERGE, CHAIN, COMMON |
| Event trapping | ON TIMER(n) GOSUB, TIMER ON/OFF/STOP, ON KEY(n) GOSUB |
| Error handling | ON ERROR GOTO, RESUME, ERROR, ERR, ERL |
| User functions | DEF FN, RANDOMIZE |
| File management | KILL, NAME, FILES, MKDIR, RMDIR, CHDIR, SHELL, ENVIRON |
| Date/time | DATE$, TIME$, TIMER |
| Screen | LOCATE, COLOR, WIDTH, SCREEN, KEY ON/OFF/LIST |
| Graphics | PSET, PRESET, LINE, CIRCLE, DRAW, PAINT, GET/PUT (sprites), VIEW, WINDOW, PALETTE, PMAP |
| Sound | SOUND, BEEP, PLAY (MML) |
| Memory | DEF SEG, PEEK, POKE, BSAVE, BLOAD |
| Hardware I/O | OUT, INP, WAIT, MOTOR, STICK, STRIG |
Tests
72 interpreter tests, 14 kernel tests, 69 compiler tests -- all passing.
bash tests/run_tests.sh # interpreter
python -m gwbasickernel.test_kernel # Jupyter kernel
Documentation
Full Sphinx documentation in docs/:
cd docs && pip install -r requirements.txt && make html
License
MIT License. See LICENSE.