Atari BASIC lister

Open a .BAS file saved with SAVE "D:NAME.BAS" (copy it out of a disk image with the Atari 8-bit disk tool). The program is listed as text, with the variable table alongside. Download as ATASCII gives a file you can ENTER back into Atari BASIC.

How the file is laid out: seven little-endian pointers (LOMEM, VNTP, VNTD, VVTP, STMTAB, STMCUR, STARP) are followed by the variable name table, the variable value table, and the tokenised lines. Each line is a line number, a length, and statements; each statement has its own length and a statement token. Numbers are 6-byte BCD floats (an excess-64 exponent of 100 and five bytes of decimal digit pairs); strings carry a length byte; variables are $80 plus their index. Turbo-BASIC XL’s extra tokens are shown as [stmt n] / [op $n].

Type or paste text, or paste bytes as hex, and see both forms side by side. Click any character in the character set to insert it. End-of-line is $9B. Graphics characters use the nearest Unicode symbols, not the exact ROM font.

A 40×24 GRAPHICS 0 screen. Click a cell and type; arrows move the cursor; Inverse video types inverse characters; pick a character below to paint with the mouse. Export as assembler .byte lines or BASIC DATA in internal screen codes (what goes into screen memory), as ATASCII text lines, or as a 960-byte binary.

The 16 hues × 16 luminances, NTSC or PAL. Click a colour for its register value, POKE 712,n (background and border), and the matching SETCOLOR. The colours shown are an approximation — real machines and televisions vary.

Share link copies a link to the open tab. ATASCII text can be written by hand as ?atascii= (for example ?atascii=HELLO%20ATARI); screens and the palette’s PAL/NTSC choice travel packed. Tokenised .BAS files are opened from your disk and never travel in links.

To run and edit BASIC programs on an emulated Atari, use the BASIC tab of the Atari 8-bit computer page.