View Full Version : IBM Personal Computer XT/370

Steven Schmitt
November 22nd, 2005, 09:45 AM
I have a few parts from a computer made by IBM. The IBM XT/370 was a standard XT computer with a pair of cards with a 370 co-processor on it. The computer could run 370 programs and was used for 370 program development.

I have the cover with the "Personal Computer XT/370" tag on it. I also have the two 370 processor cards. If I had a complete IBM XT I could make a complete computer but I have no software.

The 370 processor was a special Motorola 68000 that had special pico code to execute 370 instructions. The 68000 had internal pico code that was modified for IBM to make these co processor cards.

The cards were code named Washington cards.

I would be willing to sell these items to a person or place that would keep them in a better place than I have. The best place would be a museum.

IBM may have also made an AT/370 but I am not sure, in any case the cards I have have the short XT plugs.

Does anyone have diskettes or manuals for this system?


November 22nd, 2005, 04:51 PM
Wow, that one is an oddball.

I don't know where you would find software for that. Besides the 370 emulator, it also had a terminal emulation card in it to hook up to a real 370. You would code and debug using the emulator and then upload using the terminal emulator.

I imagine it has a special diagnostics diskette. I also imagine that there is the 370 development environment - probably not a full version of MVS or VM, but at least an editor, assembler, debugger, etc.

More common was the 3270 PC, which was just the emulator.

The problem with these machines is most people don't have the IBM mainframe to connect to. The thing that makes the machine unique is useless unless it connects to the mainframe.

Terry Yager
November 23rd, 2005, 08:07 AM
They also use a special video display & keyboard, don't they? (I'm thinking sum'n like 24 "function" keys).


Steven Schmitt
November 26th, 2005, 04:38 PM
The XT/370 did not sell very well and IBM sold the remaining stock to other IBM sites. We got a bunch of them and used them as normal XT's. The 370 card functioned as a memory card.

They had normal keyboards and looked just like any other XT. I don't think they had any connections to a mainframe, however that was a normal option for any XT.

We did use one to run a 370 exerciser program and in that mode operated as a normal 370.

I looked at the cards and I have two identical 370 cards. I thought it was a pair of cards but maybe it was just one card.

I am cleaning out all the old junk and if I cannot find a home for this stuff it will be tossed.

I also have an Evergreen keyboard but that is still in use. It has the pine tree tag instead of the AT tag.


November 27th, 2005, 07:49 AM
It's an interesting machine, but there are not going to be too many takers for the parts.

Have you tried the Classcmp mailing list?

Sadly, I find that as I get busier I have to limit my scope. PCjrs are hard enough.

Steven Schmitt
December 9th, 2005, 06:50 PM
I thougt about this a bit and will save the plastic face plate from the XT/370 case and the two cards. With those few parts it would be possible to make an XT/370 and not take up much room.

This computer should be at the Endicott Historical Society as it is a part of their history. In the same way I would like to get an IBM 5100 computer for the local Historical Society but that computer is way too rare.

The way IBM managed their product lines the IBM 5150 (PC) would never have happened without the IBM 5100. It is probably the most significant computer ever, even though it did not sell very well or was that much of a computer. The product line was the 5100, 5110, 5120, 5150. There may have been some others inbetween the 5120 and 5150.

December 9th, 2005, 07:32 PM

Did you work for IBM near Endicott?

Micom 2000
December 10th, 2005, 02:25 AM
Muellers Upgrading and Repairing PCs has a section on both the 3270 and the XT/370. The book's text is available on the net. At one point I had an IBM monitor for them. It also requires a controller as it uses a different graphic system. The keyboard was also slightly altered. It had a "hot key" for switching between the 8088 and the 370. There were at least 3 cards needed one of which was the "EM" card for connecting to a 370, a "P" card, Processers, and an "M" card, memory.


June 25th, 2006, 04:41 AM
There's one on eBay, sounds like an interesting machine!


July 4th, 2006, 12:44 PM
Isn't this thing that you are talking about?