Interface 1 ROM versions

There seem to be different ROM versions for the Sinclair Interface 1:

Version 2 of the ROM fixed bugs including the famous low RAMTOP bug which crashed a lot of programs, and also improved the speed of formatting.

Version 3 (if it was ever released) improved compatibility with the Sinclair QL.

To check the I/F ROM version, enter the following line after switch-on:

CLOSE #0: PRINT PEEK 23729

ROM V1 will return: "0"

ROM V2 will return: "80"