ROM BIOS of ATTPC6300 (also the Olivetti M24)

There are two 2764 EPROM chips, One high and one low.

BIOS version 1.21

File names: PC63H121.BIN  8,192
            PC63L121.BIN  8,192
See picture for reference.

Original EPROM M5L2764K

Image Source: TOP853 Programmer