The IBM 7531 Industrial Computer is an Intel 80286-based "AT" computer, mounted in a steel frame and surrounded by a heavy duty housing. It is ventilated by a large fan with a particle filter and is fitted to a base designed to allow the computer to be bolted to the floor. Accordingly, it was designed for use in "industrial plant-floor environments".

The type 7531 is part of the former IBM Industrial Computer line. It is effectively "twinned" with the 7532 Industrial Computer. The 7532 has identical computer specifications to the 7531, but is housed in a rack-mounting case rather than the 7531's floor-mounting case. Both correspond in terms of computer specification to the IBM Personal Computer AT [type 5170]. The 7531 and 7532 directly follow the 5531, an industrial model based around the Personal Computer XT [5160]. The 7537, based on the later Personal System/2 [PS/2] line, supercedes the 7531 and 7532.

The 7531 initially shipped with a 6MHz 80286 processor (later models had an 8MHz 286). The system board shipped with 512KB of memory onboard, with a number of options to extend it with expansion cards.

A video card was considered a prerequisite, however CGA [Color Graphics Adapter] and EGA [Enhanced Graphics Adapter] colour options were available, as the intended monitor [7534 Industrial Graphics Display, also with filtered fans] is capable of EGA modes. (Despite the recommendations and available options, the Technical Reference suggests that a monochrome adapter can be used instead.)

The system shipped by default with a "new" high density 1.2MB 5.25" half height floppy disk drive. Up to two full height 20MB hard disks were available as an option. The controller for the drives was the only expansion card included with the basic configuration.

The keyboard was a then brand-new design (at least for x86 IBM computers as far as I have seen...): the 101 and 102 key layouts that still provide the basis for the vast majority of keyboard layouts today.

The 7531 was never going to be a particularly popular machine, due to its specialised nature. Nevertheless it is an interesting variant of the 5170 AT, which saw the introduction of some interesting features before the IBM Personal Computer line did.

Original announcements from IBM. Announcement letters from the present back to the early 1980's are searchable at IBM (see resources).

185-053 - US Announcement Letter, May 21st 1985
ZG85-0246 - EMEA Announcement Letter, June 18th, 1985

The following are executable self-extracting disk images originally provided by IBM for use with the 7531 and 7532 computers. They were once publically available on the IBM Industrial products website, but are no longer available from IBM. Many thanks to Louis Ohland, who provided working copies of these images.

7531_2CL.EXE - 7531/2 Customer Level Diagnostics
7531_2AD.EXE - 7531/2 Advanced Diagnostics
7531_2KU.EXE - 7531/2 Keyboard Utilities

The following extracts are directly from:
IBM 7531/2 Industrial Computer Technical Reference System Unit [P/N 6523261]
First Edition (July 1985)
Chapter 1 [System Unit], p. 26,27,51,52,53

I have added images of the devices being discussed, and a few corrections.

Note: Diagrams are oriented as the two system board images, except keyboard connector.
They were approximated from enlargments of the system board outline, which is why they're so blocky.

Open the case

First, pull out the fan filter. Find and remove three screws on each side attaching the metal housing to the pedestal base (or in my case, find them missing). Locate two recesses at bottom of rear bezel and remove screws within (or discover them AWOL too). From the front of the computer pull the main body away, pushing upwards if it sticks. It will move clear of the rear bezel, with the front bezel remaining attached. The body should slide right off (and back on again).

Remove computer from floor mount

With the case open, remove the two screws holding the fan filter slot/guide on the left hand side (a driver with a 3/16" or 5mm hex socket makes light work of them). Then, on the other side of the machine, remove the four prominent screws in square formation (5/16" hex socket). Disconnect everything from the grounding point on top (3/16" again), and unhook the power cord from the power supply and thread it out of the way. From the front, grip the internal "box" [right hand in the recess on the right, left just behind the power supply] and slowly slide it forwards. The "box" alone is heavier [">18Kg (40lb)"] than the floor mount, so be ready to take the weight as you slide it off. It slides back into place in the reverse manner.

Remove system board

Pull cards and disconnect cables (you'd never guess). Remove pair of screws [marked S] (3/16" hex socket), next to J8 [ISA slot] and J18 [RAM jumper] (one each). Squeeze the two retaining clips [marked R] in corners on left and lift board above. Repeat with remaining clips. With all clips clear, slide system board out.

IBM Announcement Summary
- hit "Search Announcements" on the left to search the Announcement Letter archives.

Industrial Computers and Displays
- archive.org mirror of IBM Industrial Products website from 1996.

IBM Archives: IBM 7535 Manufacturing System
- IBM archive exhibit demonstrating type 7535 robot (albeit connected to an IBM PC and not an IBM Industrial Computer)

Industrial Computers
- Industrial Computers index at Louis Ohland's "Ardent Tool of Capitalism"

Photos
- Various photographs of my 7531-041, 7534-002 and P/N 1388076 (in harsh industrial environments)

This page gathered together by Daniel Wright [dw_junon of 9999hp.net]
I look forward to your complaining and pillaging.
Generic psuedolegal disclaimer.
Last touched 2007-04-10 15:29 UTC