Memory options for an HP 1000 (HP 21MX / 2112A)

Marc Verdiell marc.verdiell at
Fri May 22 01:45:24 CDT 2015


Super useful info again. In the meantime the machine has arrived, in very
good shape. I'll post pictures when I have time tomorrow, and a video
hopefully. I took a quick look inside to confirm

- there is a DCPC and a MEM protect card

- Memory controller is an older 2102A

- Three are three 8k 2102A memory boards

- No MEM card in slot 112

- Under the processor board there is a screwed on card, which seems to have
ROM on it. Microcode I presume, but I don't know if that's the one you were
talking about. I'll post photos to confirm

The IO cards and the paper tape reader / punch that came with it suggest
that it was configured with a paper tape reader, a paper tape punch, a mag
tape and a TTY interface. A plausible story is that this was an early
machine setup for paper tape and TTY and didn't have extended memory. The
early 2102A controller fits that picture well. 

So I might be in the hunt for the cards or alternate solutions you




From: "J. David Bryan" <jdbryan at>

On Tuesday, May 19, 2015 at 23:12, Marc Verdiell wrote:


> Thanks, very useful info, and the manual is indeed what I was missing.


You're welcome.



> But now where to find the DMS, with two cards in particular, that's 

> not going easy to find both that match...


First, are you sure that the machine does not have DMS installed?  It was a
very common option that became standard later on, as all versions of the RTE
operating system after RTE-II (circa 1976) required it.


Second, if the machine originally came with DMS but was stripped for resale,
then possibly only the MEM card (in slot 112) was removed.  The firmware
card is screwed onto the CPU board on the underside of the machine and is
only accessible if the bottom cover is removed.  So maybe it was overlooked,
and the availability of MEM cards is likely to be reasonable, as the same
card (but with different firmware) was used in the E/F-Series machines.


Third, if the machine has neither DMS part, then indeed finding an M-Series
DMS firmware card might be difficult.  However, DMS firmware was also
included with the later M-Series Fast FORTRAN Processor firmware (product
number 12977B).  Again, the FFP was a common option, and availability of
that card might be better than the older standalone DMS firmware card.


Fourth, if you can find a standalone MEM card, the M-Series DMS/FFP firmware
source is part of the HP 1000 Software Collection on Bitsavers, so you could
burn the required firmware PROMs and install them on a 12791A Firmware
Expansion Module card, which plugs into the I/O backplane and cables to the
CPU board.  Both the FEM and the MEM were used on E/F-Series machines, so
availability should be reasonable.


Finally, the simplest HP operating system that used DMS (RTE-III) had
additional hardware requirements: a Memory Protect card, a Dual-Channel Port
Controller (i.e., DMA) card, one of several console I/O cards, a Time- Base
Generator (i.e., clock) card, and either an HP 7900A or 7905/06/20/25A hard
drive and its associated I/O interface(s).  The latter may be the most
difficult and expensive part.  You can avoid the hard drive and use Ansgar
Kueckes' HPDrive emulator with an HP-IB I/O card, but that requires RTE-IVB
as the minimum OS, which requires at least 96KW of memory (128KW if you want
to do anything other than boot the system :-).  MP and DCPC also were
exceedingly common options, so I'd be surprised if your system didn't
contain them, unless they've been stripped out for resale.


Without DMS, you're limited to 32KW.  In that, you could run (with some
additional hardware, most notably an HP hard drive) DOS-III or RTE-II.  

Without a hard drive, you'd be limited to running one of several paper tape
or mag tape-based HP OSes.  There are third-party OSes that run on the 1000,
but I know nothing about them.


At least software is no problem; virtually everything that HP developed for
the 2116/2100/1000 machines is available via the Bitsavers collection.


                                      -- Dave



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