2026-02-15 16:56:02 -05:00
|
|
|
|
# Language Reference
|
|
|
|
|
|
|
|
|
|
|
|
## Data Types
|
|
|
|
|
|
|
|
|
|
|
|
| Type | Suffix | Description |
|
|
|
|
|
|
|------|--------|-------------|
|
|
|
|
|
|
| INTEGER | `%` | 16-bit signed |
|
|
|
|
|
|
| SINGLE | `!` | 32-bit float |
|
|
|
|
|
|
| DOUBLE | `#` | 64-bit float |
|
|
|
|
|
|
| STRING | `$` | Up to 255 bytes |
|
|
|
|
|
|
|
|
|
|
|
|
## Operators
|
|
|
|
|
|
|
|
|
|
|
|
`+`, `-`, `*`, `/`, `^`, `\` (integer div), `MOD`, `AND`, `OR`, `XOR`, `EQV`,
|
|
|
|
|
|
`IMP`, `NOT`, `<`, `=`, `>`, `<=`, `>=`, `<>`
|
|
|
|
|
|
|
|
|
|
|
|
## Numeric Functions
|
|
|
|
|
|
|
|
|
|
|
|
`SGN`, `INT`, `ABS`, `SQR`, `SIN`, `COS`, `TAN`, `ATN`, `LOG`, `EXP`, `RND`,
|
|
|
|
|
|
`FIX`, `CINT`, `CSNG`, `CDBL`
|
|
|
|
|
|
|
|
|
|
|
|
## String Functions
|
|
|
|
|
|
|
|
|
|
|
|
`LEN`, `ASC`, `CHR$`, `VAL`, `STR$`, `LEFT$`, `RIGHT$`, `MID$`, `SPACE$`,
|
|
|
|
|
|
`STRING$`, `HEX$`, `OCT$`, `INSTR`, `INPUT$`
|
|
|
|
|
|
|
|
|
|
|
|
## File Functions
|
|
|
|
|
|
|
|
|
|
|
|
`EOF`, `LOC`, `LOF`
|
|
|
|
|
|
|
|
|
|
|
|
## Pseudo-variables
|
|
|
|
|
|
|
|
|
|
|
|
`ERL`, `ERR`, `CSRLIN`, `INKEY$`, `DATE$`, `TIME$`
|
|
|
|
|
|
|
|
|
|
|
|
## Literals
|
|
|
|
|
|
|
|
|
|
|
|
Decimal, `&H` hex, `&O` octal, `D` exponent (double), `E` exponent (single),
|
|
|
|
|
|
type suffixes (`%`, `!`, `#`)
|
|
|
|
|
|
|
|
|
|
|
|
## Statements
|
|
|
|
|
|
|
|
|
|
|
|
| Category | Statements |
|
|
|
|
|
|
|----------|------------|
|
|
|
|
|
|
| Output | `PRINT`, `LPRINT`, `PRINT USING`, `WRITE`, `CLS` |
|
|
|
|
|
|
| Variables | `LET`, `DIM`, `ERASE`, `SWAP`, `DEFINT`, `DEFSNG`, `DEFDBL`, `DEFSTR` |
|
|
|
|
|
|
| Control flow | `GOTO`, `GOSUB`/`RETURN`, `FOR`/`NEXT`, `IF`/`THEN`/`ELSE`, `WHILE`/`WEND`, `ON...GOTO`, `ON...GOSUB` |
|
|
|
|
|
|
| Input | `INPUT`, `LINE INPUT`, `DATA`/`READ`/`RESTORE`, `INKEY$` |
|
|
|
|
|
|
| Program control | `RUN`, `RUN "file"`, `CONT`, `STOP`, `END`, `NEW`, `LIST`, `CLEAR` |
|
|
|
|
|
|
| Sequential I/O | `OPEN`, `CLOSE`, `PRINT#`, `WRITE#`, `INPUT#`, `LINE INPUT#` |
|
|
|
|
|
|
| Random-access I/O | `FIELD`, `LSET`, `RSET`, `PUT`, `GET`, `CVI`/`CVS`/`CVD`, `MKI$`/`MKS$`/`MKD$` |
|
|
|
|
|
|
| Program I/O | `SAVE`, `LOAD`, `MERGE`, `CHAIN` |
|
|
|
|
|
|
| Error handling | `ON ERROR GOTO`, `RESUME`, `RESUME NEXT`, `RESUME n`, `ERROR`, `ERR`, `ERL` |
|
|
|
|
|
|
| User functions | `DEF FN`, `RANDOMIZE` |
|
|
|
|
|
|
| File management | `KILL`, `NAME` |
|
2026-02-22 12:18:17 -05:00
|
|
|
|
| Screen | `LOCATE`, `COLOR`, `WIDTH`, `SCREEN`, `KEY ON`/`OFF`/`LIST`, `KEY n,"string"` |
|
2026-02-15 16:56:02 -05:00
|
|
|
|
| Graphics | `PSET`, `PRESET`, `LINE`, `CIRCLE`, `DRAW`, `PAINT` |
|
|
|
|
|
|
| Sound | `SOUND`, `BEEP`, `PLAY` (MML parser, PulseAudio backend) |
|
|
|
|
|
|
| Misc | `POKE`, `KEY`, `TRON`/`TROFF`, `OPTION BASE`, `MID$` assignment, `COMMON` |
|
|
|
|
|
|
| System | `SYSTEM` |
|
|
|
|
|
|
|
|
|
|
|
|
## Graphics
|
|
|
|
|
|
|
|
|
|
|
|
Graphics mode is activated with `SCREEN 1` (320x200, 4 colors) or
|
|
|
|
|
|
`SCREEN 2` (640x200, monochrome). Drawing commands render to an internal
|
|
|
|
|
|
framebuffer and output via [Sixel graphics](https://en.wikipedia.org/wiki/Sixel),
|
|
|
|
|
|
which works in terminals like xterm, mlterm, foot, and WezTerm.
|
|
|
|
|
|
|
|
|
|
|
|
### Drawing Commands
|
|
|
|
|
|
|
|
|
|
|
|
- `PSET (x,y), color` / `PRESET (x,y)` — set/reset individual pixels
|
|
|
|
|
|
- `LINE (x1,y1)-(x2,y2), color [,B|BF]` — lines, boxes, filled boxes
|
|
|
|
|
|
- `CIRCLE (cx,cy), r [,color [,start, end [,aspect]]]` — circles and arcs
|
|
|
|
|
|
- `PAINT (x,y), fill, border` — flood fill
|
|
|
|
|
|
- `DRAW string` — turtle graphics mini-language (U/D/L/R/E/F/G/H, M, C, S, B, N)
|
|
|
|
|
|
- `POINT (x,y)` — read pixel color
|
|
|
|
|
|
- `COLOR fg, bg` — set foreground/background colors
|
|
|
|
|
|
|
|
|
|
|
|
### Example
|
|
|
|
|
|
|
|
|
|
|
|
```
|
|
|
|
|
|
SCREEN 1
|
|
|
|
|
|
LINE (0,0)-(319,199), 1
|
|
|
|
|
|
CIRCLE (160,100), 80, 2
|
|
|
|
|
|
PAINT (160,100), 3, 2
|
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
|
|
## Sound
|
|
|
|
|
|
|
|
|
|
|
|
- `SOUND frequency, duration` — play a tone (frequency in Hz, duration in clock ticks)
|
|
|
|
|
|
- `BEEP` — play the default beep
|
|
|
|
|
|
- `PLAY string` — Music Macro Language (MML) string for melodies
|
|
|
|
|
|
|
|
|
|
|
|
Sound output uses PulseAudio when available; commands are silently ignored otherwise.
|
|
|
|
|
|
|
2026-02-22 12:18:17 -05:00
|
|
|
|
## Full-Screen Editor (TUI)
|
2026-02-15 16:56:02 -05:00
|
|
|
|
|
2026-02-22 12:18:17 -05:00
|
|
|
|
When running interactively, GW-BASIC 2026 presents the authentic full-screen
|
|
|
|
|
|
editor:
|
|
|
|
|
|
|
|
|
|
|
|
- 25×80 screen buffer with free cursor movement (arrow keys)
|
|
|
|
|
|
- Press Enter on any screen line to re-enter it as BASIC input
|
|
|
|
|
|
- Insert/Overwrite toggle (Insert key)
|
|
|
|
|
|
- Home/End/Delete/Backspace/Escape for line editing
|
|
|
|
|
|
- Ctrl+C interrupts running programs
|
|
|
|
|
|
- Uses the ANSI alternate screen buffer for clean terminal restore on exit
|
|
|
|
|
|
|
|
|
|
|
|
### Function Keys
|
|
|
|
|
|
|
|
|
|
|
|
Default F1-F10 bindings match the original GW-BASIC:
|
|
|
|
|
|
|
|
|
|
|
|
| Key | Default | Key | Default |
|
|
|
|
|
|
|-----|---------|-----|---------|
|
|
|
|
|
|
| F1 | `LIST ` | F6 | `,"LPT1:"` + Enter |
|
|
|
|
|
|
| F2 | `RUN` + Enter | F7 | `TRON` + Enter |
|
|
|
|
|
|
| F3 | `LOAD"` | F8 | `TROFF` + Enter |
|
|
|
|
|
|
| F4 | `SAVE"` | F9 | `KEY ` |
|
|
|
|
|
|
| F5 | `CONT` + Enter | F10 | `SCREEN 0,0,0` + Enter |
|
|
|
|
|
|
|
|
|
|
|
|
- `KEY ON` — show the function key bar on line 25
|
|
|
|
|
|
- `KEY OFF` — hide the bar
|
|
|
|
|
|
- `KEY LIST` — display all definitions
|
|
|
|
|
|
- `KEY n, "string"` — redefine a function key
|
|
|
|
|
|
|
|
|
|
|
|
### Piped Mode
|
|
|
|
|
|
|
|
|
|
|
|
When stdin is not a terminal (piped input), the TUI is not activated.
|
|
|
|
|
|
The interpreter reads lines from stdin and writes output directly to stdout,
|
|
|
|
|
|
suitable for scripting and test harnesses.
|
