HP-41C double memory module?

[Dieter]

I think most HP-41 users are familiar with the Standard RAM module 82106A (64 registers) and the Quad-RAM 82170A (256 registers) that appeared a bit later.

Now I seem to remember that there also was a Double RAM module with 128 registers. No, not the X-Memory module, but something between the mentioned single and quad capacity RAMs for the 41C. Since I could not find any reference to this other than a sentence in a Wickes book on Synthethic Programming, I wonder if this module really existed and what its HP part number may have been. Maybe someone here knows more about this?!

Dieter

[Hans Brueggemann]

dieter, afaik, there was never such an item produced by HP.
it was one of the most popular hacks at that time to put two single-density RAMs into a single module in order to free up ports for other modules.
double density modules shared their fate with the famous Austrian internal 4-module upgrade pc-board and lost much of their popularity with the arrival of the CV and CX mainframes.
(there was an article in the german version of the ELRAD magazine by joerg warmuth that described the hack in detail. have it somewhere on my hard-disk...)

[Dieter]

(02-03-2016 10:04 PM)Hans Brueggemann Wrote:  afaik, there was never such an item produced by HP.

Thank you for your feedback.

In 1982 a German version of Bill Wickes' "Synthetic Programming on the HP-41C" was published. On page 2 a short experiment is described which uses a synthetic STO M, generated by a classic "module pulling" procedure. Here the user is instructed to set SIZE 063 with a regular memory module resp. SIZE 127 if it's a double one. Do you really think the author referred to a custom-made, hand-soldered module instead of a regular piece of HP hardware? Maybe someone has the English version of the Wickes book and report what's written there?

This is what makes me wonder. And somehow I also seem to remember other references to such a module.

But of course I may be completely wrong here – after all it's more than 30 years ago now. ;-)

Dieter

[Massimo Gnerucci]

(02-04-2016 08:07 PM)Dieter Wrote:  

(02-03-2016 10:04 PM)Hans Brueggemann Wrote:  afaik, there was never such an item produced by HP.

Thank you for your feedback.

In 1982 a German version of Bill Wickes' "Synthetic Programming on the HP-41C" was published. On page 2 a short experiment is described which uses a synthetic STO M, generated by a classic "module pulling" procedure. Here the user is instructed to set SIZE 063 with a regular memory module resp. SIZE 127 if it's a double one. Do you really think the author referred to a custom-made, hand-soldered module instead of a regular piece of HP hardware? Maybe someone has the English version of the Wickes book and report what's written there?

This is what makes me wonder. And somehow I also seem to remember other references to such a module.

But of course I may be completely wrong here – after all it's more than 30 years ago now. ;-)

Dieter

I have the english version I bought in 1980 (with Addendum to fourth printing) and this paragraph is on page 1; still referring to a double density module .
I never saw such a module, nor mentions of it in catalogs.

Maybe it was planned but, eventually, the project 41 soon evolved to the CV version making a quad-module more appealing to update the C units.

[Gene]

I completely believe that Bill Wickes was referring to the user created dual memory module.

These were all the rage in 1979 and 1980, often advertised as a service in the PPC Journal by Emmett Ingram I think.

HP never made such a beast. Period. :-)

[rprosperi]

(02-04-2016 09:03 PM)Gene Wrote:  I completely believe that Bill Wickes was referring to the user created dual memory module.

Dieter - Keep in mind that before he was "Bill Wickes", he was Bill Wickes, PPC member, and exactly the kind of guy that probably made his own dual memory module.