Tracor Aerospace AN/UGC-129  
Written by Accutron on 2012-05-27  

Devices included in this entry:

Tracor AN/UGC-129 Teletypewriter Set (pictured in thumbnail)
Tracor MU-734/UGC Teletypewriter Magnetic Tape Unit


The Tracor AN/UGC-129 Teletypewriter Set was the standard U.S. Air Force teletype terminal throughout the 1980s and 1990s. The AN/UGC-129 is a nuclear-hardened, microprocessor-controlled full-duplex teletype with 8K of memory and 120cps printing speed, and is considered suitable for air, land and sea applications. The unit pictured here is the first variant of the AN/UGC-129, equipped with a high speed rotating type head and direct readout. A later, more common variant, the AN/UGC-129(V)1, is virtually identical, but features a conventional dot matrix print head and a 40-character electroluminescent line display. The (V)1 variant can be easily identified by its protruding readout area which overhangs the keyboard.

Among its numerous installations, the AN/UGC-129 was notably an integral component of the Minuteman II ICBM Launch Control Facility.

AN/UGC-129 Teletypewriter Set Operation and Maintenance Instructions (Partial File) (PDF)
Tracor UGC-129 & MU-688 Advertisement (PDF)

From Ed Peet, AN/UGC-129 project lead (slightly edited for punctuation):

"As you probably know, the AN/UGC-129 was designed and built at Tracor in Austin. It contains one of the first microprocessors made up of discrete components. It's been a while, but as I recall, the microprocessor had about 1.5 Kbytes of PROM and a separate data SRAM (I can't remember its size). The 129 was a successor to the AN/UGC-120, which was a successor to a cockpit printer for the FB-111 fighter. Bob Nelson designed the original cockpit printer and 120. I went to work for Tracor in 1974 and took over the design, including the microcode that controlled the printer. In 1977, Sherry Hurwitz and Terry Kimball came to work at Tracor and designed various parts of the 129. Mike Cavazos came a few years later and did more design.

"One of the things that I remember about this series of terminals is that we took high-speed movies of the rotating printhead. The firmware was designed to rotate and translate the printhead as fast as possible using a stepper motor. When the printhead reached its destination, the firmware had an algorithm to reverse the direction in order to slow it down quickly. The high speed movies helped us design the algorithm to maximize the speed.

"Another thing I remember is the cold testing. These printers had to work down to -40C, so we had huge temperature chambers. It was a real pain to test at this temperature.

"At one time there were quite a few (11 as I recall) of these printers (either 120s or 129s) installed in Air Force One. Boeing (I think) was fitting Air Force One in Seattle, and they were having a problem getting the terminals to work, so they flew me up to Seattle to find the problem. When I got there, they had already found the problem in the power distribution system, so I got a nice tour of Air Force One and all the technical equipment installed in it. Unfortunately, they wouldn't let me take any pictures."


Tracor AN/UGC-129 in operation.


Tracor AN/UGC-129 Teletypewriter Set.


AN/UGC-129, closeup of keyboard and front panel. The keyboard is socketed, and can be detached by releasing a series of screws on the inside of the front panel.


AN/UGC-129, internal controls.


Tracor MU-734/UGC Teletypewriter Magnetic Tape Unit, a rare accessory for the AN/UGC-129.


MU-734/UGC, closeup of magnetic head.


MU-734/UGC, rear panel.

This article is part of the [Digital Computer Equipment] exhibit.

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