486SLC2 CPU Upgrade
192-145  IBM 486SLC2 Processor Upgrade 85xx 
slc_util.exe  8555-SLC2 processor upgrade utility disk (720K image!)

194-377  Options by IBM: Processor Upgrade Products
392-223 IBM PS/2 Models 56 SLC and 57 SLC 486 SLC Upgrade Modification

IBM 486SLC2 Processor Upgrade FRU 10G7103 P/N 32G3672 (EMEA)  P/N 2609582-2620 (USA)
 
This can be installed on a 8556 SX / SLC, 8557 SX / SLC


      Remove any installed Math-Co (and also any math-Co empty socket) Install plastic guide and plastic insert on planar. 
      Insert any removed Math Copro into 486SLC2 Processor Upgrade board in U1. 
      Install Upgrade board until pins are fully-seated, and edge-snaps click into place. 
 
 
 
 

486SLC2 Upgrade Board

U1 Socket for PLCC 387SX 
U3 Reverse of mounting pins 
U8 486SLC2 CPU 
 
 
 
 


FEATURES AND PERFORMANCE ENHANCEMENTS
o   IBM 486SLC2 microprocessor (40MHz internal/20MHz external) 
o   486SX-compatible Instruction Set 
o   Internal memory cache controller and integrated 16KB cache memory 
o   Improves cpu throughput up to 271% for 386SX-20, 99% for 386SLC-20 systems. Throughput is up to 53% better than for 486SX-20 based systems and up to 20% greater than 486SX-25 based systems.
o   16-byte wide cache line size 
o   Enhances performance, particularly computer-intensive applications 
o   Allows upgrade of Model 56 SX / SLC and Model 57 SX / SLC and M57 SLC systems 
o   Installs into a Math Co-Processor socket connector 
o   Provides a socket for 80387SX 20MHz, or equivalent Math Co-Pro 
o   16MB real memory addressability 
o   64TB (TB = terabytes) virtual memory addressability

PS/2 8555 486SLC Upgrade Performance Failure H127022
 
IBM PS/2 8555SX systems may fail to function at an increased processor speed after installing 486SLC processor upgrade.
 
PROBLEM ISOLATION AIDS:
     A limited number of PS/2 8555SX system boards contain a module located to the left of the memory SIMM sockets labelled "Pinto 3A #64F3646." This chip may conflict with the bus timings of the 486SLC Processor upgrade which results in a reduction in processor performance. The "Pinto 3A" chip only affects IBM option P/N13H6694, FRU P/N13H6697, card assembly P/N78G2521.
       _________________________________________
      |                                        _|_______System board
      |       ___________                       |
      |      (___________)fuse                  |
      |                          Memory Sockets |
      |     ______________       __  |   __     |
      |    |              |     |  |    |  |    |
      |    |              |     |  |    |  |    |
      |    |  PINTO 3A    |     |  |    |  |    |
      |    |  64F3646     |     |  |    |  |    |
      |    |              |     |  |    |  |    |
      |    |              |     |  |    |  |    |
      |    |______________|     |  |    |  |    |
      |                         |  |    |  |    |
      |                         |  |    |  |    |
      |                         |__|    |__|    |
      |_________________________________________|
 
The record says the affected planars were removed from stock. There are two main variants of the 8555 SX, the Early (ZM16) and Late (ZM22) planars. Both of my sample boards do not have 64F3646.

     The diskette utility provided with the 486SLC Processor Upgrade contains a benchmark test called PUZZLE.EXE.  When this test is performed on a system with the processor upgrade, the results are consistent with the test results of the original system board with the Intel 386SX processor installed (45-125 seconds).
  

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