IBM Personal System/2 Model 55 SX

Machine Type 8555-X61
Serial 55-PZ973
Manufacturer IBM Corp., United Kingdom
Date June 1990

Physical description

Type Desktop
Dimensions (HxWxD) 102 x 406 x 397 mm
Weight 8.65 Kg
Drive bays 2 x 3.5" half-height, both accessible
Power supply 90 W, 110-220VAC (DAT.: 20/90)

Main board

Manufacturer IBM (chips 9011), planar id FBFF
BIOS IBM, Nov. 2, 1988 (128 Kb, sticker 03/05/90)
Processor Intel 80386SX-16MHz (32-bit) PQFP
Coprocessor Socket for optional i80387SX Math coprocessor
Memory 2 sockets for 85ns 72-pin SIMMs (PS/2 type), parity checked (*)
Max on system board 8 Mb (2 x 4 Mb)
Max. using adapter cards 16 Mb (about 15,5 Mb usable)
Bus Micro channel (MCA) 16-bit
Expansion slots 3 (16-bit, one w. video ext.)
Interface HDD (ESDI), FDD
Video Integrated 16-bit VGA display adapter (256 Kb, max. 320x200, 256 colours or 640x480, 16 colours)
Ports PS/2 keyboard, PS/2 mouse, serial (UART 16550A), parallel, VGA


Installed RAM 2 x 2 Mb 85ns (type 6249) SIMMs
Memory IBM 2-8 Mb 286/386SX mem. expansion adpt. (id. F7F7 [mid-91]) w. 4 x 2 Mb 85ns type 6249 SIMMs (91-14 to 29)


Diskette drive 1.44 Mb, 3.5" slim (Mitsubishi MF355C)
Hard disk Model WD-387 (60 Mb), 3.5" half-height (cables 21:90)


Acquisition Sept. '02, gift (was in a deposit of dismissed appliances)
Condition Very good, working
Installed O.S. Olivetti MS-DOS 5.00 (Italian)
Repairs/modifications None
Current status All hw working
Current O.S. None
Spare parts Almost everything, incl. drives, planar, etc.


(*) 80ns SIMMs OK, does not accept 70ns SIMMs.


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This page was first published on the web on Dec. 24, 2002
Last revised Dec. 31, 2004