8525 Common Devices

Type/Model Information
Earphone Connector
Bolt-down Feature


Type/Model Information (from William R. Walsh (original HERE)

The IBM PS/2 Model 25 personal computer is an all-in-one unit. The monitor and computer are in one case. In order to get a feel for what your particular system is capable of, you need to find out what is inside. In a perfect world, all the model numbers would be unique and well documented. This being IBM, however, that isn't the case. For the best possible assessment of what you have (or don't have), the best thing you can do is open your system unit (see the instructions here) and take a look at it. This will answer your questions and builds your character (maybe).

Three specific systems and one upgrade model number exist as provided by IBM. All four systems differ greatly in planar (mainboard) design, processing speed, display, storage capability, and upgrade parts that can be used. I've seen conflicting labeling on systems and sometimes people do strange things, such as swapping monitor assemblies with a lower end system.

Should you desire to see your system's type-model and serial number, you will find them on a label underneath the lower left hand corner of the monitor bezel. The system should be facing you, as in the picture below.

Where to find your 25's type-model number...


Earphone Connector

An earphone connector is provided at the rear of the system unit to allow the user to disable the internal beeper (speaker) and listen to the sound output through a set of earphones. The internal beeper is disabled whenever a plug is inserted into this connector.

The connector will accept any 1/4-inch diameter audio plug. A monophonic earphone with an impedance level of 15 to 35 ohms is recommended. Some earphones with an impedance level as high as 100 ohms may also be acceptable. The drive level is fixed so that the sound level will be directly related to the sensitivity of the earphones. Earphones with 1/8-inch plugs may be used with adapter plugs.

Note: This is not Line-Out, but a 33 KΩ series resistor can be used to drop the audio signal down to a line level. Watch IBM PS/2 Model 25 Earphone to Line Level (by Hakemon Mike) for more info.


Bolt-down Feature

The IBM 8525 security, auditability and control features include a bolt-down feature that allows the user to physically secure the system unit to a table or desk. Three holes are provided in the system unit. Using the center hole only allows the user to rotate and tilt the system unit. If the two outside holes are used, the system unit will tilt, but will not rotate.

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Louis Ohland, Peter Wendt, William Walsh, David Beem, Tatsuo Sunagawa, Jim Shorney, Tim Clarke, Kevin Bowling, Tomáš Slavotínek, and many others.

Ardent Tool of Capitalism - MAD Edition! is maintained by Tomáš Slavotínek.
Last update: 27 May 2022 - Changes & Credits | Legal Info & Contact