8556/57 Cached Processor Upgrade

191-201 Cached Processor Option for Model 8557
SHS04G5106 IBM PS/2 Cached Processor Option HML
EPRM IBM PS/2 Cached Processor Option for Mod. 56/57

rf855657.exe 8556/8557 reference diskette v2.10 -supports SLC2/SLC3 upgrades

8556/57 Diags Disk Ver 2.04 or better supports all 8556/57 386SX / SLC systems, including 8556/57 systems with processor options: 386SLC, 486SLC2, and 486SLC3.

8556/57 Cached Processor Upgrade FRU 92F0078

Note the unpopulated jumper "BYPASS JUMPER".

Not having one in-hand, I see the wires from the OS1 outline, going under the heatsink.

Upgrade Installation


  • IBM 386SLC-20 with Internal memory cache controller and 8KB cache memory
  • Improves processor throughput up to 88% depending on application
  • Installs into a math co-processor 121-pin socket connector
  • Provides a socket for 80387SX 20MHz or equivalent math co-pro.

Content created and/or provided by:
Louis F. Ohland, Peter H. Wendt, David L. Beem, William R. Walsh, Tatsuo Sunagawa, Tomáš Slavotínek, Jim Shorney, Tim N. Clarke, Kevin Bowling, and many others.

Ardent Tool of Capitalism - MAD Edition! is maintained by Tomáš Slavotínek.
Last update: 03 Dec 2023 - Changelog | Legal Info & Contact