IBM PS/1 User Manual

If the system board has cache memory modules already installed, the com-
puter has 128K of cache memory. Upgrade to 256K by adding memory
modules as follows:
Bank 2 Add four 28-pin modules: 32K × 8, 25 ns SRAM.
Tag Replace existing module with one 28-pin module: 32K × 8,
20 ns SRAM.
If you are installing cache memory in a board with no cache memory previ-
ously installed, install 128K or 256K as follows:
Bank 1 Add four 28-pin modules: 32K × 8, 25 ns SRAM (for 128K or
256K).
Bank 2 Add four 28-pin modules: 32K × 8, 25 ns SRAM (for 256K).
Tag Add one 28-pin module: 32K × 8, 20 ns SRAM (for 256K) or
8K × 8, 20 ns SRAM (for 128K).
Cache memory jumpers are preset at the factory for 128K cache memory.
Reset the jumpers for 256K by moving them forward to cover two jumper
pins, as shown in Figure 4-15 on page 4-19.
Table 5-1. Processor Jumper Settings for J23, J24, and J25
486SX System Boards
486SX 486SX/487
Math
486SX/486
Overdrive
486SX/Pentium
ODP
J23
J24
J25
1, 2
1, 2
1, 2
1, 2
1, 2
2, 3
1, 2
1, 2
2, 3
1, 2
1, 2
2, 3
486DX and 486DX2 System Boards
486DX 486DX2 Pentium ODP
J23
J24
J25
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
2, 3
5-18

IBM PS/1 Specifications

General

Processor	Intel 80286 or 80386
Processor Speed	10 MHz (80286)
RAM	1 MB (expandable to 2 MB or more)
Storage	40 MB hard drive
Floppy Drive	3.5" 1.44 MB
Graphics	VGA
Ports	Serial, Parallel, Mouse