HP-41 CY Turbo: Ebay offer in German language


Hi folks,

the HP-41 CY Turbo at Ebay:
Can anyone tell me the differences between HP 41 CY and HP41 CX ?
(the Ebay text is in German language).
I know that it is a great machine and also extremely rare.

Item number: 180092629766



Edited: 5 Mar 2007, 6:57 a.m.



the CY has a 64K RAM box built-in, and also a 'turbo' switch,

which will increase the CPU speed.

The RAM box is organized as two 32K pages,

which can be switched by software, even under program control.

However, since the seller writes that the unit

requires more than one press on the ON key to turn on,

I assume that the backup battery

on the machine up for auction is low,

and so the RAMBox OS has vanished.

A new backup and my CY-INIT module would presumably

restore the unit to full functionality;-)




Hi Raymond,
thanks a lot for your detailed clarification!

64K RAM is absolutely breathtaking!!
It is like four DOUBLE HEPAX modules.
Is the CY rambox organized like HEPAX RAM, i.e. with machine coding capability ?

Good to know that you have an INIT module available for recovering!

Edited: 5 Mar 2007, 7:45 a.m.


Hi Rich,

the principal structure of each RAM block is

similar in all ROM-simulating devices,

so the individual pages can be used for own ML programs, of course.

There are some differences between the HEPAX *ROM*

and the W&W RAMBox OS regarding the bank switching schema.

The HEPAX ROM uses all four banks of a single page,

using the HP standard bank switching opcodes,

whereas the W&W OS uses a variation (other combination)

of opcodes to switch between (CY RAM) banks 1 and 2.

However the HEPAX RAM isn't bank switched.

You could use a HEPAX ROM, either a real one, or one on a Clonix,

in combination with the CY, being able to use

one of the two RAM banks of the CY,

but you can't load the HEPAX ROM code into a CY,

as the RAM banks of a CY are switched in a different way,

and there are 'only' two banks, not four as the HEPAX ROM expects.

The above is an (incomplete) overview of some things to notice

about HEPAX and W&W CY, but it should give you an idea;-)

About the CY INIT module:

Yes, this was a hard piece of work, I made it from scratch.

It's fully menu-driven, and safely restores

a CY RAMBox with weird contents to a clean and working state,

including loading RAMBox OS A and B, and optionally OS/X.

There are various articles about RAM boxes and the CY

in the hpmuseum forum and articles archive.




Thank you, Raymond!
Very interesting issue!
What is the $price for a CY-INIT module (on Zeprom or where)?
Or did you upload the code to the database of "the other hp41.-rg fan site" for loading into clonix or hepax ?

Edited: 6 Mar 2007, 11:09 a.m.

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