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Wednesday, September 1, 2021

CONTINUITY: HP 9825 Repair Part 11—Debugging the Keyboard, Display, and Printer Board

The repairs of earlier episodes got the Hewlett-Packard 9825 laboratory computer working, but only with a keyboard, display, and printer module borrowed from a working 9825. Now the focus moves on to repairing the module from the unit fried when its power supply blew up. This is a worrisome task, since this module's circuit board includes a custom Hewlett-Packard application-specific integrated circuit (ASIC) which, all these years later, might as well be made of gold-pressed unobtainium.

Posted at September 1, 2021 15:15