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

Marc Verdiell marc.verdiell at
Sat May 23 19:48:02 CDT 2015

Yes I was asking myself the same question, and your answers continue to help
a lot. 

I think I should retrace the path of technology evolution. Start getting it
up with paper tape tests and BCS. That probably means working mostly in
assembly and getting to know the most basic level of the machine. Which is
just about what the doctor prescribed. 

Then add the mag tape for which I have the tape and the cards.

I got a 7900 disk though (with cables and power supply, but no interface
cards to go with it!). I'd love to get that one going later on. Then it
would make sense to have the bigger memory to run disk based OS systems. So
7900 interface card and memory are definitely on my hunt list...

By the way I also have a punched card reader which I just restored.
Documation ML600, but the exact same model that HP re-branded I believe. Do
you know which interface cards I need to connect it to the HP-1000? I
suppose one of the 16 bit IO ones with a driver to go with it?

Sorry to keep picking your brain, but that is so much more efficient than
trying to piece it together (usually wrong at first) from an disorganized
pile of documentation!


From: "J. David Bryan" <jdbryan at>
>> So I might be in the hunt for the cards or alternate solutions you
>> mentioned.

>I'd suggest that the question to answer first is whether you want to expend

>the effort and expense to gather the moderate amount of additional hardware

>necessary to run one of the more advanced disc-based OS versions that can 
>use DMS.  Note that the design of the memory mapping hardware in the 1000 
>requires explicit software support (i.e., programming of the DMS hardware) 
>in order to use more than 32KW of memory.  Earlier OSes that did not 
>support DMS will simply ignore all memory in the machine over 32K, even 
>when DMS is present.
>With the hardware you have, you can run a paper-tape based OS, such as BCS 
>(the Basic Control System) in 24K.  BCS is fairly primitive, but it does 
>offer an assembler, FORTRAN IV, and ALGOL compilers, and paper-tape BASIC 
>interpreters were also available (from the user contributed library).
>The hardware requirements for running the disc-based RTEs are listed on 
>these HP Computer Museum pages:
> -- Dave

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