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Glenn’s Computer Museum

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AN/ASQ-155 Ballistic Computer (A-6 Intruder)

The AN/ASQ-155 is a ballistics computer used in the Grumman A-6E Intruder fighter-bomber. The A-6 carried a crew of two, a pilot and, to his right, a bombardier-navigator who operated the navigation, radar, and ballistics systems. There are two major components of the ASQ-155. The control pedestal sits in between the legs of the navigator/bombardier as highlighted in the cockpit picture of the A-6. The computer unit lives in the base on the pedestal; our pictures have pulled it out of the base and include a closeup of some of the computer logic boards.

Several references state that the computing component is a version of the IBM System/4 Pi computer family. For example, US Patent 4057800 describes the basic approach for bomb targeting based on pulsed radar inputs and includes the statement "A particular computer could be one identified by the Department of Defense as ASQ-155 and typified by the IBM 4 Pi computer."

However, I don't believe that my unit contains an IBM 4Pi computer since the logic is almost entirely composed of Texas Instruments chips; I believe IBM would have used its own chips. Furthering the confusion is a picture of an earlier A-6 ballistic computer, the AN/ASQ-61, which externally looks just like our device (this is seen at the top of the fuzzy page to the right) The ASQ-61 is listed as manufactured by Litton, which seems consistent with use of TI devices. Yet our device is clearly labeled as an ASQ-155.

We have a lot of detail about the operation of the ASQ-155 since we have the A-6E flight manual that includes coverage of the ASQ-155. The sample page here shows the functions of the control stick. The detailed description in this document confirms that our device is really a ASQ-155.