IBM Personal System/2 Model 40 SX

Machine type 8540-045
Serial 55-MKY20
Manufacturer IBM Corp., United Kingdom
Date July 1991

Physical description

Type Desktop (may be converted to floor standing) (26 JUL 1991 print inside top cvr, 27 JUN 1991 print on drives tray)
Dimensions (HxWxD) 169 x 440 x 394 mm
Weight 12.6 Kg
Drive bays 1 x 3.5", 3 x 5.25", all accessible
Power supply 197 W, 110/220VAC switchable (9127)

Main board

BIOS IBM, Apr. 4, 1991 (26 Kb)
Clock 20 Mhz, 0-2 wait states
Processor Intel 80386SX (32-bit) PQFP
Coprocessor Socket for optional i80387
Memory 3 sockets for 85ns 72-pin SIMMs (PS/2 type), parity checked (accept faster 70ns SIMMs)
Max on system board 16 Mb (about 15,5 Mb usable)
Bus AT 16-bit 
Expansion slots 5 (AT 16-bit), on riser card
Video Integrated 16-bit VGA display adapter
Interface HDD (2 units type IDE/ATAPI), FDD (2 units)
Ports PS/2 keyboard, PS/2 mouse, serial (UART 16450), parallel, VGA


Installed RAM 1 x 8 Mb 70ns and 2 x 4 Mb 80ns SIMMs on planar (und.)
Ethernet SMC 8013EWC (14-93) ADDITION


Diskette drive 1.44Mb, 3.5" slim (Alps DFP723, 91-15)
Hard disk Maxtor 7080AI (80 Mb) IDE/ATA, 3.5" slim (03 JUL 1991, cables 27/91)
2nd Hard disk Maxtor 7040AI (40 Mb) IDE/ATA, 3.5" slim (11 JUN 1991) ADDITION


Acquisition Mid-99, free (was in a deposit of dismissed appliances)
Condition Very good, working
Installed O.S. Olivetti MS-DOS 5.00 (Italian)
Repairs/modifications Added ethernet card and second hard drive, replaced existing 2 x 2 Mb memory SIMMs
Current status All hw working
Current O.S. IBM PC-DOS 5.00 (Italian)
Spare parts Almost everything, incl. drives, planar, etc.


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This page was first published on the web on Nov. 11, 2001
Last revised May 24, 2004