Model 50 (8550-021)

EPROMs: 27256 x4

ZM13: 90X6815
ZM14: 90X6816
ZM15: 90X6817
ZM16: 90X6818 
BIOS Revision '00' - 13 February 1987

Unknown FRUs
BIOS Revision '01' - 09 May 1987


Model 50Z:

EPROMs: 27512 x2

Unknown FRUs
BIOS Revision '02' - 28 February 1988

ZM5: 15F8361 or 15F8365 externally, 15F8365 internally
ZM6: 15F8362 or 15F8366 externally, 15F8366 internally
BIOS Revision '03' - 18 April 1988