Repairing a $25,000 HP Workstation to Run Pac-Man

An HP9863C partially disassembled on a workbench

The microcomputer revolution of the 1970s and 1980s turned computers from expensive machines aimed at professionals into consumer products found in the average household. But there always remained a market for professional users, who bought equipment that was so far ahead of consumer gear it seemed to belong in a different decade. While a home computer enthusiast in 1981 might fork out a few hundred dollars for an 8-bit machine with 64 KB of memory, a professional could already buy a 32-bit workstation with 2.8 megabytes of RAM for the price of a brand-new sports car. [Tech Tangents] got his hands on one of those machines, an HP Series 200 9863C from 1981, and managed to get it up and running.

The machine came in more-or-less working condition. The display cable turned out to be dodgy, but since it was just a straight-through sub-D cable it was easily replaced. Similarly, the two 5.25″ floppy drives were standard Tandon TM100-2As which [Tech Tangents] had some experience in repairing, although these specific units merely needed a thorough cleaning to remove forty years’ worth of dust.

An HP9863C running Pac-ManAfter a thorough scrub of all the internal boards, the machine duly booted from its accompanying BASIC boot disk. [Tech Tangents] got the machine with a few disks containing some basic utilities as well as some graphics demos, which were certainly impressive for their age. Getting the computer to run anything else turned out to be a bit of a headache however: since this was not a mass-market machine, very little software has survived into today’s online archives. And even what little is available is difficult to transfer to the machine, since HP used several floppy formats over the years that are largely incompatible with each other, making disk images useless unless you happen to have the exact same type of floppy drive that they were made on.

One way to solve this issue is to use the HP’s GPIB bus to connect it to a reasonably modern PC with a GPIB interface card, then run a program called HPDRIVE that emulates a GPIB hard drive to the old workstation. This worked fine for at least some of the disk images [Tech Tangents] found at the HP Computer Museum, allowing him to run a few more graphics demos, including a rather crude version of Pac-Man. Games were anyway not high on developers’ priority lists, since this was a computer aimed at serious users who wouldn’t spend $25,000 on a machine just for fun. It’s a neat twist of irony then, that the MAME video game emulator works perfectly fine emulating some of those ancient HP workstations.

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