# GW_BASIC_COMPATIBILITY.md

Version 1
- PRINT
- LET
- INPUT
- END
- REM
- CLS
- LIST
- RUN
- NEW
- CLEAR
- NEWS new release notes command

Version 2
- GOTO
- IF THEN

Version 3
- FOR/NEXT
- WHILE/WEND
- GOSUB/RETURN

Version 4
- Default Green display mode on load, refresh, and restart
- MODE GREEN / MODE DOS / MODE AMBER as direct and program commands
- COLOR foreground and COLOR foreground,background in DOS mode, applied to printed output going forward
- PRINT trailing semicolon continuation
- Source case and spacing preservation for LIST, SAVE, LOAD, and CLS
- Graphics: SCREEN, PSET, PRESET, LINE, CIRCLE, PAINT, DRAW, GET, PUT, VIEW, WINDOW
- Line-numbered syntax, runtime, and type mismatch errors during RUN
- CHR$ and ASC with range and empty-string errors
- DIM and multi-dimensional numeric/string arrays
- Catalog demos for arrays, ASCII, COLOR, and graphics
- DATA, READ, and RESTORE with line-numbered OUT OF DATA errors
- Multi-dimensional numeric and string arrays
- SOUND frequency,duration using browser Web Audio
- Browser-safe sequential file I/O: OPEN, CLOSE, PRINT #, INPUT #, LINE INPUT #, EOF
- LOCATE row,column text cursor positioning
- BREAK interrupt with Escape, Ctrl+C, Ctrl+Break/Pause when exposed by the browser, and a mobile-only BREAK button for touch devices without recent keyboard use
- POINT graphics function and PAINT flood fill
- Numeric functions: ABS, ATN, CDBL, CINT, COS, CSNG, EXP, FIX, INT, LOG, RND, SGN, SIN, SQR, TAN
- String functions: ASC, CHR$, ENVIRON$, HEX$, INKEY$, INPUT$, INSTR, LEFT$, LEN, MID$, OCT$, RIGHT$, SPACE$, STR$, STRING$, VAL
- Binary string round-trip functions: MKI$/CVI, MKS$/CVS, MKD$/CVD using browser little-endian integer/IEEE 754 storage
- Terminal copy/paste support with plain-text copy and smart quote normalization during paste

Browser compatibility notes
- ENVIRON$ returns a small virtual environment rather than host operating system variables.
- INKEY$ and INPUT$ read from the browser keyboard buffer while a program is running; INPUT$(n,#fileNumber) is not implemented.
- Binary string conversion functions round-trip inside Classic BASIC but are not exact Microsoft Binary Format random-access file compatibility.

Future
- PLAY music macro support
- Random-access file I/O and device files
- Printer commands
- Exact hardware-level GW-BASIC graphics behavior