Servicing Personal Computers, 3rd Edition

250 Servicing Personal Computers

ROM release dates and machine ID

The ROM release date and machine ID can be found by examining the area of read-only

memory extending between absolute memory locations FFFF5H and FFFFCH. The ROM

release information (not found in all compatibles) is presented in American date format using

ASCII characters. The machine identification (ID) byte is unique to a particular member of the

PC family and can be found in absolute memory location FFFFEH. Table 6.11 shows values of

ID byte and original ROM release date.

Fault finding in the

PC

family

The procedure for locating faults in the PC, PC-XT, PC-AT, and compatible ...