SOME TRAP ERRORS HAVE BEEN CAUSED BY INCORRECT MEMORY BEING USED. THE TABLE BELOW GIVES THE MANUFACTURING P/N'S, RESISTORS PRESENT AT THE TOP RIGHT (IBM MANUFACTURED) OR MANUFACTURER CODE MARKING ON THE SIMM CASING MADE BY VENDOR FOR THE DIFFERENT SPEEDS AND SYSTEMS WHERE USED.
P/N23F9779 IS THE IBM MANUFACTURED 100NS MEMORY AND IS RECOGNIZED BY THE R1 AND R2 RESISTORS AT THE TOP RIGHT. P/N68X6254 IS THE VENDOR MANUFACTURED EQUIVALENT AND HAS ONE OF THE MARKINGS. EITHER ONE CAN BE USED IN THE 8570 16MHZ OR 8555.
---------------------------------------------------------------- PART NUMBER | SPEED | MARKINGS | WHERE USED ---------------------------------------------------------------- 23F9779(IBM)| 100 | R1 AND R2 RESISTORS | 8570 16MHZ ____________| |__________________________| 68X6254(OEM)| | MSC2321-10YS18A | AND | | HB56D512361B-10 | | | MH512361B-10 | 8555 | | ZA3617 | | | THM265102S-10 | ---------------------------------------------------------------- 65X6249(IBM)| 85 | ONLY R1 RESISTER | 8570 20MHZ ____________| |__________________________| 8555 68X6127(OEM)| | MNB36512S85 | 8570 16MHZ | | THM365120S-85 | OPTION | | MSC2321-85YS18A | 6450605/9 | | HB56D512361B-8 | ---------------------------------------------------------------- 68X5806(IBM)| 80 | ONLY R2 RESISTOR | 8570-A21 | | | 8570-R21 ----------------------------------------------------------------