!!!How to find the revision number of Atari Basic

With the BASIC cartridge put into your 400/800 or BASIC switched on, type (e.g. after the READY prompt)

? PEEK(43234) 

and then press RETURN.

The computer will give you an result.

|162|Revision A|First Atari BASIC cartridge, 8K ROM.
|96|Revision B|Found built-in on the 600XL and early 800XLs. Never supplied on cartridges.
|234|Revision C|Found on later 800XLs, the 800XLF, XEGS and all XE computers. Limited cartridge production run.

For an description of the known errors, see the Wikipedia Article on ATARI Basic:

See also [OS Versions]