IBM Personal System/2 Model 50

Machine Type 8550-021
Serial BK55-0051532
Manufacturer IBM Corp., United Kingdom
Date September 1987

Physical description

Type Desktop (7 Sep 1987 print inside front panel)
Dimensions (HxWxD) 140 x 360 x 420 mm
Weight 9.5 Kg
Drive bays 2 x 3.5" half-height (accessible), 1 x 3.5 or 5.25" half-height (internal)
Power supply 94 W, 90-137/180-265 VAC auto sense (8735)

Main board

BIOS IBM, Feb. 13, 1987 (128 Kb, planar id FBFF, MCA model/submodel FC04)
Processor Intel 80286-10 MHz (16 bit), PGA
Coprocessor Intel 80287-6 MHz math coprocessor, DIP ADDITION
Memory 2 sockets for 150ns 30-pin SIMMs (PS/2 type), parity checked
Max on system board 1 Mb (2 x 512 Kb - only accepts 512 Kb SIMMs)
Max using adapter cards 7 Mb
Bus Micro Channel (MCA) 16-bit
Expansion slots 4 (16-bit, one w. video ext.)
Interface FDD (2 units)
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 512 Kb 150ns SIMMs
Controller IBM ST-506 Fixed Disk Controller (id DFFD) (chip 8728)


Diskette drive 1.44 Mb, 3.5" half-height (Alps DFL713A)
Hard disk Model WD-325N (20 Mb, type 30), 3.5" half-height


Acquisition Feb. 2002, gift, was in a deposit of dismissed appliances
Condition Very good, working
Installed sw MS-DOS 6.22, MS-Windows 3.1 (Italian)
Current status All hw working, but hard drive has many bad sectors and makes some noise
Current O.S. IBM DOS 3.30 (Italian)
Spare parts Floppy drive


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This page was first published on the web on Sept. 23, 2002
Last revised Oct. 21, 2004