ATASCII - BASIC - Unicode Converter

Atari’s Special Characters

AtariBASIC LST and BAS files use ATASCII encoding so they cannot be edited directly in modern editors. Fortunately for Atari enthusiasts ATASCII special characters have a Unicode mapping! Just install Atari Classic Fonts.

Editing AtariBASIC

The built-in AtariBASIC editor is clunky and doesn’t support lines over 120 characters long – less than half of the legal length! I created the AtariTools plugin for Sublime Text to support AtariBASIC with full syntax coloring. With this plugin you can also use the Build command to run your BASIC code in the Atari emulator.

AtariBASIC Converter

Use this tool to convert an AtariBASIC BAS or LST file to ATASCII LST and Unicode ULST files.

📂 Upload File…

Detected: — | Input size: 0 bytes

10 REM Hello from ATASCII!
20 FOR I=1 TO 10
30 PRINT "ATASCII lives!"
40 NEXT I
50 END

Naive

⬇ Download LST (ATASCII) ⬇ Download ULST (Unicode)

ATASCII Encoding

ATASCII (ATari ASCII) is the character encoding used by Atari 8-bit computers (400/800/XL/XE). It differs from standard ASCII in several ways:

End-of-line is 0x9B (not 0x0A as in ASCII). BASIC lines end with $9B.
Graphics characters occupy the lower control-code range ($00-$1F) and the upper range ($7B-$FF). These include box-drawing, playing card suits, and special symbols.
Inverse video characters mirror the normal set but with the high bit set, creating a "negative" appearance.

This converter uses PUA trio-encoded Unicode in the Atari Classic font's private-use area by default — compatible with the Atari Classic font family. Check Naive to use box-drawing characters and math sans-serif letters for display in any Unicode font. Use the download links to get ATASCII output suitable for Atari emulators.

Tokenized .BAS Files

Atari BASIC stores programs in a tokenized binary .BAS format. Upload a .BAS file to detokenize it into BASIC source code.

Atari-Compatible LST Files

In Sublime Text plugin AtariTools the Build command converts to ATASCII before sending the code to the emulator.

To create ATASCII LST files for use with your Atari emulator:

Write your Atari BASIC program in any text editor using Unicode text.
Upload or paste the code into this converter.
Download the result as ATABASIC.LST and rename as preferred.
Copy the .LST file to your emulator's shared hard drive folder (H: device).
In the emulator, type ENTER "H:ATABASIC.LST" to load the program.

References

6502-Tools on GitHub — Support for Atari BASIC and Atari 6502 Assembly.
AtariBASIC — Curated 6502 source for the Atari BASIC cartridge ROM.
AtariMania — Site preserving classic Atari 8-bit software.