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

J. David Bryan jdbryan at
Wed May 20 12:35:46 CDT 2015

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 

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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