IBM PS/1, Hardware Maintenance Service

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486SX 33MHz (72-Pin Memory SIMM) System Board
Layout
Note: Jumpers must be checked against information above.
BH1 External Battery
J1 Keyboard
J2 Mouse
J3 Serial Port A
J4 Serial Port B
J5 Parallel Port
J6 Display Signal
J7 Diskette
J8 Power
J9 Hard Disk Drive
J11 Riser Card
J14 Video Feature
J15 Video Disable (normal operation is pin 1, 2)
J16 Cache Jumper (must be in pin 2, 3 for upgrade to 256K)
J17 Cache Jumper (must be in pin 2, 3 for upgrade to 256K)
SIMM sockets can be populated in any order.
J19 RAM 72-Pin Memory SIMM Socket - Bank 3
J20 RAM 72-Pin Memory SIMM Socket - Bank 2
J21 RAM 72-Pin Memory SIMM Socket - Bank 1
J22 RAM 72-Pin Memory SIMM Socket - Bank 0
J23 Processor-type jumper. See 5-18.
J24 Processor-type jumper. See 5-18.
J25 Processor-type jumper. See 5-18.
J26 LED Connector—Power: 1, 2 Hard Disk Drive: 3, 4
J27 Speaker Volume Control (WT only)
SP103
Password Bypass
SP193 Beeper
U7 System ROM
U19 Cache Memory Socket (for address module) 128K/256K
U28 Cache Memory Socket Bank 1
U29 Cache Memory Socket
U30 Cache Memory Socket
U31 Cache Memory Socket
U37 Cache Memory Socket Bank 2
U38 Cache Memory Socket Bank 2
U43 Cache Memory Socket Bank 2
U44 Cache Memory Socket Bank 2
U45 486DX, 486 Math, 486DX2, 486 Overdrive, or Pentium** ODP
Processor
U46 486SX Processor
Parts/Test Point Locations
5-15