Call for manuals and maybe floppies: IBM 8100

Paul Berger phb.hfx at
Thu Aug 26 19:54:12 CDT 2021

On 2021-08-26 6:48 p.m., Jay Jaeger via cctech wrote:
> My next project once I finish my IBM 1410 FPGA implementation (so, a 
> couple of years out, probably) would be to write an emulator for the 
> boat anchor known as the IBM 8100.  I had exposure to these things 
> back in the 1980s.  The project was not really a success: the DPPX 
> operating system was way overkill for the underpowered machine, and 
> wasn't reliable enough or capable enough to run them at remote 
> locations with central administration.
> The machine had some fairly sophisticated features:
>    Two groups of 64 sets of registers with 8 32 bit registers each
>    Auto increment and auto decrement indexed addressing
>    Address translation - but not paging
>    A primitive form of I/O channel
> True story:  The early releases of DPPX were just awful buggy.  We 
> ended up dedicating 3 conference rooms (with the dividers open) for a 
> "warm room" for something like 3 months, housing our personnel and IBM 
> personnel up from Texas.  At one point one of the IBM'ers was 
> overheard on a public phone in the hallway of our public building 
> telling someone he was there "to help the hicks from Wisconsin".  That 
> got reported to our management and to IBM's management, and he was on 
> the next flight back to Texas.  ;)
> On the flip side, I was testing database recovery (it was my thing, 
> back in the day - though we did not end up using the database / 
> transaction manager).  I found some bugs in the database log journal 
> recovery process.  I mentioned it to one of the IBM'ers in passing, 
> also pointing out it wasn't urgent since we were not going to use DTMS 
> anyway, at least not soon.  He pretty much begged me to report it - 
> and anything else I found wrong.  Completely polar opposite attitude 
> of the guy in the previous paragraph.

The 8100 came out during my first stint in field service, most of the 
machines we saw where 8130s that ran the DPCX operating system and they 
where purchased to replace 3790 distributed processors. We had one 
customer who bought an 8140 and I helped with a model upgrade on it, 
which involved removing all the logic gates as one unit and replacing 
them with the upgraded one.  It would have been quicker and probably 
cheaper to ship an entire new machine, but they where advertised as 
field upgradeable so.....   A few years later when I saw the inside of a 
S/38 I recognized the packaging of the system as being identical to the 
8140 except the 8140 did not have the built in CRT console or magazine 
diskette drive. This 8140 was running DPPX but I don't know how the 
customer got on with it as it was not my account.  It is said that the 
8100 processor is the Universal Controller (UC), but I am hoping it was 
a beefed up on from the UC engine that ran several of the "Industry 
Systems" controllers such as 3274 (NDS), 3601 (Banking), and 3651 
(retail store systems).


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