EAI PACE TR-48 (3)

YEAR: late
ITEM: Analog Computer
COMPANY: Electronic Associates, Incorporated (EAI)
COUNTRY: U.S.A.
IN OUR COLLECTION: Yes

This analog computer gives new meaning to the term "desktop". At four feet wide, almost two feet deep and just over two feet high, this computer just barely fits on a desk (and there's no room left over for your notepad and pencil -- see the link to Documents). Weighing in at between 320 and 425 pounds (depending upon the configuration), this particular computer sits on a custom made desk which holds up to six patchboards.

The TR-48 was the most complete desktop analog computer available at its time. It solved sophisticated problems that required high-speed repetitive operation and iterative techniques with a capability equal to many console computing systems. Characteristics include a 48 amplifier capacity, the widest bandwidth of any desktop computer of its time, iterative solution and multi-scale capacity, high-speed repetitive capability, 4 independent time scale changes, solid state readout, removable patch panels for flexibility, and a compact and mobile low power drain. It was used for aero-space, biomedical, chemical engineering, and food technology.

Here's how the Operator's Manual describes the TR-48.

"The PACE© TR-48 is a fully transistorized, general purpose analog computer. Consisting entirely of solid-state circuit elements, the TR-48 is compact in size and is suitable for desk top mounting. The computer is able to operate stably and accurately in normal office ambient conditions; there is no need for large primary power systems or special colling duct installations since the power requirements are small."

As to their claim that the TR-48 is compact in size, that is a relative claim made in comparison to the computers of the 1950's...all we can say is that the author of that operator's manual never attempted to lift this 425 pound monstrosity into the back of a van! Surprisingly, the claim about power consumption it true...all this computer needs is a regular 115v wall outlet!

We are still looking for information as to when it was originally sold to the public. We can confirm that it was sometime before 1961.

Our collection contains three TR-48 computers, a custom made desk to hold the TR-48 patchboards, enough wiring to reach Long Branch, NJ, and extensive documentation.

We are still looking for information as to when it was originally sold to the public. We can confirm that it was sometime before 1961.

It seems that the TR-48 was part of the Apollo moon program. The "Apollo Monthly Progress Report" dated August 31, 1962 includes the following comment at the bottom of page 35.

"The fabrication and development of test logic simulation and switching circuits for use with the in-flight test system has continued, and the roll simulator for TR-48 computer is under construction. The miniature control and display system breadbroad model is being modified to improve performance and increase reliability."

In addition, the TR-48 was still be used in the 1970's to simulate the stars and their movements so that the staff could test the star tracking system used by Apollo astronauts. In a side note, it is interesting to see that the star tracking system aboard the Apollo capsule used an early Intel 8080 microprocessor.
Our thanks to Kevin Cooper of Winchester, Kentucky for finding both these reference! (3-2-2013)

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IMAGES

Click on any of the images below to see the slideshow.

Documents

Documents for this item have not yet been scanned or not yet posted. There are a lot of pages...contact us if you have an immediate need. (Although there are not a lot of "immediate needs" for a 70+ year old computer!)

Very Rare

In addition to the three in our collection, we know of five other TR-48 computers. The first is located in Bletchley Park, England (the famous WWII code-breaking center). The Bletchley Park machine is cared for by John Blackburn, his son Chris and the other members of the Retro Beep Collector's Club. [As of about 2005 the Retro-Beep Club has become England's National Computer Museum and the collection is still in the same building.]

The second TR-48 is located in Padova, Italy at the Friends of the World Treasures Computer Museum which is operated under the auspices of UNESCO.

The third is part of the Digibarn collection in California. They have pictures of their machine...note the delivery truck with a lifting gate and the nice pnuematic truck they used to bring it into the barn. My nephew, 2 students, and I carried ours and almost ruined four backs!
[NOTE: As of 2024 the collection from Digibarn has been moved to the System Source collection near Baltimore. You can find their website here.]

A fourth TR-48 is located in the magnificent London Science Museum. Although it may not be on display. Don't worry they have plenty of other computing treasures to view up on the second floor.

A trip to lovely San Jose, California will let you see the fifth TR-48 in CHM. Don't miss this museum!

For more information, click on the link(s) below.

     National Computer Museum: Bletchley Park, England

     FWT Computer Museum; Padova, Italy

     DigiBarn; California

     London Science Museum

     Computer History Museum: London, England

If you know the location of any other of these items, please let us know by contacting us at Director@TheComputerChurch.com .

OUR DEFINITIONS OF RARITY

One of a Kind: Only known existing item.
Exceedingly Rare: Only 2 to 10 known to exist.
Very Rare: Only 11 to 25 are known to exist.
Rare: Only 26 to 50 are known to exist.
Difficult: Difficult to find.
Available:Can be commonly be purchased.
Unknown: We cannot make a determination.

(For comparison: Many people consider the Apple-1 computer to be rare. As of 2025 there are 92 confirmed and probable Apple-1 computers.)

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