Thoreau BASIC

A GW-BASIC–compatible interpreter that runs on bare metal (a Windows version is available, too).

The data segment is sized to the largest block of conventional memory the firmware (or Windows) reports, which on a modern machine is gigabytes.

Language

• (mostly) GW-BASIC compatible. Programs load and save as ASCII.
• Numeric types, including 32 and 64-bit integers (%, &, &&), single and double precision, strings.
• 32 bit wide line numbers.
• DEF FN, GOSUB, ON…GOTO/GOSUB, DATA/READ/RESTORE, and the rest of the control flow.
• Error trapping: ON ERROR GOTO, RESUME / RESUME NEXT / RESUME n, ERL, ERR, ON BREAK GOTO

Graphics

• PSET, LINE, CIRCLE, PAINT and friends at native framebuffer resolution. PSET, LINE and PAINT usable with 16 color EGA or 24 bit R,G,B syntax.
• 16-color EGA palette and 24-bit color: COLOR r,g,b (and a background triple).
• Bitmaps: LOADBMP slot, file$ reads a 24/32-bpp Windows .BMP into a data-segment slot; BITBLT slot, x, y [,key] blits it, with an optional transparent color key for sprites.
• GRAMAXX / GRAMAXY (graphics) and TXTMAXX / TXTMAXY (text) are readable variables holding the actual bounds.
• SCREEN x,y requests a mode. SCREEN 1024,768 works on almost every machine and is usually the boot mode; try your native resolution for a sharper picture. GRAMAXX/GRAMAXY update after a SCREEN command.

Text

• IBM VGA 8×16 font, soft-scrolling console.
• Multiple text windows: WINDOW @n, x1,y1,x2,y2 carves a region; PRINT @n, CLS @n, LOCATE @n and COLOR @n work inside it, each window with its own cursor and pen/paper. Plain PRINT still owns the whole screen.

Memory & hardware

• A three-pointer memory model with no 64KB ceiling. Arrays in the billions of elements, if you want them.
• PEEK, POKE, VARPTR, and readable pointers into the machine: LOMEM, HIMEM, FREEBOT, FREETOP, SCRNADR, GRAPITCH.
• 64-bit HEX$ / OCT$.

Disk I/O — SAVE, LOAD, MERGE, FILES, KILL, running directly on the UEFI Simple File System.

Editing — full-screen EDIT, AUTO line numbering, and RENUM (renumbers and rewrites every GOTO/GOSUB/THEN/ELSE/ON…/RESTORE/RESUME/ERL reference).

Timing — the TIMER variable reads a high-precision clock from the CPU's invariant TSC.

New in v1.2

• CHDIR, MKDIR, RMDIR, FIELD, GET#, PUT#, LSET, RSET
• CVI, CVS, CVD, MKI$, MKS$, MKD$
• TAB(), SPC()
• OPTION BASE, ERASE
• NAME old$ AS new$
• MERGE
• DELETE
• CSGN, CDBL
• ERROR n, TRON, TROFF
• SCREEN () function

New in v1.1.3

• MID$ can be an assignment now
• ERL wasn't stored and no error line was shown when a program exited with an error
• INPUT: backspace didn't work right

New in v1.1.2

• When available RAM was less than 4 GB, the Windows version bailed out.
• BASIC lines are now fixed to 244 characters without line numbers.
• EDIT/LIST bug: when line number was greater 32767 it showed an empty line 0 instead.