IBM 5100 Personal Computer

This machine has the distinction of being very nearly the first microcomputer. I think the Altair 8800 was first, but this is a different beast: For one thing, it has CRT, keyboard, BASIC interpreter and mass storage all built in. For another, it's a much more advanced design: A microcoded 16-bit CPU executing an interpreter which in turn interprets a subset of the IBM 360 mainframe instruction set!

Technical information about the IBM 5100 computer can be found on the web, but decent pictures are rare. In January 2000 I rescued one from being thrown out (for the time being). Before stashing it in my parents' attic, I took some pictures.

The tape drive may still work in mine, but the tapes that I have are no longer readable.

The guts: Swing-out backplane with cards. Quite a few slots are empty in this one, because it only has the BASIC ROMs and only 16K of RAM. A fully configured machine would have switchable BASIC or APL, and 64K of RAM, and possibly some I/O modules.

As often the case in stuff this old, the foam has deteriorated into a sticky mess.

The machine works, but with all the strange, extinct IBM technology inside (what's the use of having the service manual if all the spare parts, as well as the diagnostic tape, are extinct?) one shouldn't get too attached to it. One of my other "museum piece" machines (the NABU) is no longer functional since its 20-year-old hard disk controller gave up the ghost.

The sales brochure

The machine came with documentation. Here is the sales brochure for an enhanced successor model. Posted without permission from IBM because I think it is historically interesting. I will remove this from the web if requested to do so.

Update: September 2004

I gave the machine to Dave Dunfield and it now resides in his museum with much better photos than these, and scanned documentation as well. Unfortuantely it no longer works, because a ROM went bad while I had it in my parents' attic.

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