Anyone want a rambox (made) for the hp 41?


Wondering how nay if any would like to experiment with
machine language programming on a hp41.

There are some solutions around but they latch up occassionally
(not good).

I am interested in building an enhanced copy of the old ERAMCO RAMBOX. I might make a few if anyone wants one.

I am planning to do a little MCODE programming on the 41, so I feel I need one ;-)

Don W



With all due respect: with Clonix, MLDL2000 and efforts underway by others I do not see why there would be interest in the good old Eramco RAMBOX. Playing with mcode can be done on the simulators as well.

And about lockups: programming mcode is almost a guarantee for locking up your calc!



Hi Meindert,

Regardless of the cause (hardware glitch or software bug)
there is NO PRACTICAL APPLICATION for a system which crashes,
(apart from as an example of human fallability).

There are enough examples of human fallability in the real world.
The oil crisis (this one is real and permanent) and environmental degradation are the main one I think about.

The answers to your question are:

An extensible hardware platform and optional HARDWARE FLAGS are an extra bonus. Since when does anyone have to STOP at the point others have reached?

I do want to politely make the point that I am only interested in practical applications for this regretably ancient machine. If others want to work on extending it I think that is JUST WONDERFUL!
that others already have is great.

Thanks to your work Meindert and Diego D. and John I. and many others we have these marvellous gadgets. They are GREAT, but they are not perfect.

I am only coming up to speed fully with all the history of these projects. However I note that these guys didn't have to BUILD THEIR OWN Logic State Analyzers. So maybe I can contribute something to all this?

What would be helpful to the community if painful for the developers is a public bug list so that if/when designs are
released the community can work on squashing them.

After all, that's what they did at hp R and D...

Have a nice day.

Don Wallace

Edited: 3 Oct 2005, 7:24 p.m.


Please contact me regarding this topic. I would like to discuss some details with you. Please remove the NOSPAM from the e-mail address.


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Dear Don,

if you create a rebuild version of the ERAMCO RAM-Box than realise the 128KByte version which includes 4 softwareselected banks...

With best wishes - Christoph Klug


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Hi Don,

You have seen Lyne Wilkins MLDL project/schematics?
PPC V9N3P27 (1982)
Note: V9N4P2



This is indeed the best starting point, and some other articles in the PPC, explaining the operation of the HP41 interface.
Also I recommend the HP41 Service Manuals, which have bits of information that is missing in the PPC articles, especially on the startup- and powerdown behavior.
Make certain that you really understand how the WROM instruction works, this can be tricky.

Must reads are:

* Inside the HP41C, article by Kelly McLellan: PPC Calculator Journal V6N7

* HP41 Bus Interfacing, article by Jim De Arras: PPC Calculator Journal V7N3

* HP41 Machine Language Development Lab, article by Lynn A. Wilkins: PPC Calculator Journal V9N3

All this information is available on the various sets of CD's or DVD's that are available at MoHPC or TOS.

Soon I will publish the VHDL source and schematics of the MLDL2000, feel free to use this as a starting point.


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