IBM B50 - Manual (Page 189)

Base Class S2 Sub-Class
S3 - S4 Description
1 A0 SCSI Drivers (generic)
B0 IDE Drives
C0 RAID Drives
D0 SSA Drives
E0 Tapes SCSI
E1 Tapes IDE
ED SCSI changer
EE Other SCSI device
EF Diskette drive
F0 CD-ROM SCSI
F1 CD-ROM IDE
F2 Read/Write optical SCSI
F3 Read/Write optical IDE
F4 - FF TBD media devices
5 A0 L2 Cache Controller including integrated SRAM
A1 L2 Cache SRAM
A8 NVRAM
A9 CMOS
AA Quartz/EEPROM
B0 - Bx Memory cards
Cyy Memory Modules (Where C is S2, S3, or S4 and yy
identifies the memory size and type).
7 A0 I 2 C bus
8 A0 Power Management Functions
9 A0 - Ax Keyboards
B0 - Bx Mouse(s)
C0 - Cx Dials
D0 Tablet
D1 - Dx Future input devices
B A0 Service processor
Appendix A. Interpreting Firmware Error Codes A-5