|Note 1||In the 11/08/82 BIOS revision, 720K diskette operation is partially supported. More information is here.|
|Note 2||Refer to the diagram here.
In the two 1982 dated BIOS revisions, chip U19 contains part of cassette BASIC and thus is not critical to operation of the computer (only cassette BASIC is lost).
For that reason, if the POST in those BIOS' discovers that U19 has failed, the POST will display "F6000 ROM" and allow booting to continue.
This is not the case for the 1986 dated BIOS revisions, because in those, U19 also contains part of the BIOS. If U19 fails in those, the motherboard will appear 'dead'.
|Note 3||The two 1986 dated BIOS revisions (01/10/86 and 05/09/86) may cause the symptom described at here.|
|Note 4||The two 1986 dated BIOS revisions (01/10/86 and 05/09/86) may not support an IBM 5161 - see here.|
|Note 5||The two 1986 dated BIOS revisions (01/10/86 and 05/09/86) contain code for 1.2M drives, however, to use a 1.2M drive, it is not as simple as upgrading the floppy controller to a high density (HD) one.
|Note 6||The copyright string in some 1501512 ROM's is "1501512 COPR. IBM 1981", and "1501512 COPR. IBM 1982" in others. The ROM's are functionally the same.|