486SLC2 CPU Upgrade

192-145 IBM 486SLC2 Processor Upgrade 85xx
192-227 PS/2 486SLC2 Processor Upgrade For PS/2 57 SX (?)
194-377 Options by IBM: Processor Upgrade Products
392-223 IBM PS/2 Models 56 SLC and 57 SLC 486 SLC Upgrade Modification

slc_util.exe 8555-SLC2 processor upgrade utility disk (720K image!) (zipped image)

Kingston SLC/Now! Installation Guide (SLC/50LEM, SLC/50GAM, SLC/50LCM)

IBM 486SLC2 Upgrade for Model 50Z (aka Kingston SLC/50LCM)
IBM 486SLC2 Upgrade for Model 56/57
   Upgrade Installation
Features and Performance Enhancements
PUZZLE Benchmark


IBM 486SLC2 Upgrade for Model 50Z
P/N 35G9581 (REV:A2), FCCID: ANO71F3079 [P] [P]

Kingston SLC/Now! Upgrade for Model 50Z (SLC/50LCM)
AS# 35G9595 (REV:A3), FCCID: ANO71F3079 [P] [P] [P]

U2 QuickLogic QL12x16 FPGA (anti-fuse)
U3 50G6950 IBM 486SLC2 50 MHz CPU
U4 PLCC Socket for 387SX FPU
VR1 LM317T Adj. regulator
U5 Kingston PLCC plug (planar)
X1 50.000 MHz Osc (MPC)

VR1 LM317T Adj. regulator set to approx. 3.6 V for the IBM 486SLC2 CPU.


IBM 486SLC2 Upgrade for Model 56/57
FRU 10G7103, P/N 32G3672 (EMEA), P/N 2609582-2620 (USA)

U1 PLCC Socket for 387SX FPU
U3 Reverse of mounting PGA socket
U8 IBM 486SLC2 CPU

Upgrade Installation

This can be installed on a 8556 SX/SLC and 8557 SX/SLC.

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


Features and Performance Enhancements

  • IBM 486SLC2 microprocessor (40MHz internal/20MHz external)
  • 486SX-compatible Instruction Set
  • Internal memory cache controller and integrated 16KB cache memory
  • 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.
  • 16-byte wide cache line size
  • Enhances performance, particularly computer-intensive applications
  • Allows upgrade of Model 56 SX / SLC and Model 57 SX / SLC and M57 SLC systems
  • Installs into a Math Co-Processor socket connector
  • Provides a socket for 80387SX 20MHz, or equivalent Math Co-Pro
  • 16MB real memory addressability
  • 64TB (TB = terabytes) virtual memory addressability


PUZZLE Benchmark

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).

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

Ardent Tool of Capitalism - MAD Edition! is maintained by Tomáš Slavotínek.
Last update: 10 Apr 2021 - Changes & Credits | Legal Info & Contact