Is there anyone writing MCODE for the HP-41?


No text...


Ya, just finished a new 4k disassembler rom, not much in the last two weeks however, been working on my motorcycle. Did the BLDROM over at TOS a few months back.




Hi Doug

Just for my database: You programmed the BLDROM? It is a 4k MCode image (with no hardware module).
There is no manual and no overlay.
Is this correct?



Hi Matthias,

Yes it is a 4K image. There is a .pdf manual at TOS.
I have done an update, improves the off poll and some other things.
The manual in .doc is better if you are interested.

Best Regards,


Hi Doug. Could you give me a URL for the manual, please?

What licence do you have on the software?

Would you please write to me, I have a proposal for you...



I have been having a go at this lately. I now have the NoVram module with the HEPAX and have been trying to write some code.
Why do you ask?


Hi Doug, Jeff.

Really cool, Doug... What sort of motorbike do you have? What are you doing on it?

Well Jeff, to be honest I am just curious. I am going to have to write a few simple routines in MCODE to do my IR module and maybe
(if it ver sees the light of day) to implement my rom expansion for the 41. I am using a different scheme to the method Diego employed
so I need to write my own MCODE for the 41 side of what amounts to an HP41 buss to IIC buss adaptor. I plan to use two PICs (one to implement the 41 microcode) and some flash ram or eeprom. All smt of course. Prototyping with standard DIP parts fairly soon.



Hi Don,

Aw, it's an old HD. 1931 VL. Did you know that those old machines literally dump oil on the road? It just goes straight through. Have to fill up the "oil" tank (half the gas tank) every 200 miles or so (hand pump it every 5) ... it just goes by the crankshaft one time .. then on the ground. Not gonna pass ANY envionmental test! The gas/oil tanks are a nightmare when they leak: about 30 pieces and all lead soldered together like a radiator. The chromoly frame is brazed together with cast iron at the joints. The springer front end is all cast iron save the springs, but i have told you more than you want to know.

Any help i can offer with your MCODE, yet i don't know much about the actual signals on ISA due to any particular function, i'm definately software on the 41 only, too clumsy to handle a soldering iron or an smt.

Best Regards,


Hi Doug,

Well thanks on the offer of (advice / asisstance with) coding;
I might just need your help sometime soon...

W.r.t. the 'cycle... well what can I say? You certainly seem to be a gultton for punishment (love hurts...). I have heard the old Harleys (etc.) want to spew their stomach contents a bit...

I think old motorcycles are a bit like women:

A Great hobby, fun to ride, very lovable but HIGH MAINTAINENCE...(?)

It's cool, I won't call the EPA (or FEMA) on ya, buddy!


Don W


I found a post from you lat year where you asked about EPROMS for the HP 41 - did you ever find anything out there? How is it possible? would love to hear about your outcome!




Hi Peter.

Diego Diaz following on from the work of J.I. has built
a hepax programmable module using a microcontroller to emulate the behaviour of a rom or rambox.
I think you have to program the module yourself. (I think Diego is a bit strapped for time, but he would want to speak for himself on this.)

I am making these (ROM) modules fully preprogrammed. I can manufacture whatever you want. Feel free to write to me:
Shortly I am releasing FORTH and PPC combined in one ROMPACK.

Don Wallace


Hi Don... all,

You're right on both... very little time (actually I'm writting this in a few hours gap between flights) and I've renewed production of Clonix & NoVRAM.

Please see my last ad:

Further info at:

I'd like to point out that Clonix is supplied with customer selected configuration which, of course, can be re-configured at will.

Sorry for the lack of time... will be back in a couple of weeks.

In the meantime, keep the 41 spirit alive!! ;-))

Regards from Spain

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