Sandbox ROM


I found a ROM image called Sandbox ROM on the internet.
Two questions:
1) is it possible to convert it from .bin format to .rom?
2) who/where/why/when was this ROM made?




the only site where you could download he Sandbox has infos about the author, Angel Martin.



Thanks Raymond.
I checked back after your response, and now the .rom file has been added in stead of the .bin format.
But I would still like to know a little more about this SANDBOX project. Is it available as a module? I've never seen one on sale.




The SANDBOX is indeed now available on the web as a .rom and .bin files, and thus works on V41 and Emu41.

As per what it is, it started as a personal project to learn MCODE programming, using Ken Emery's book as main tool. It then grew until becoming a collection of (hopefully) handy utilities.

It contains many functions published many moons ago in magazines like PPC Journal, Data File, PRISMA and HPX. All were contributions from members, and thus freely shared. My contribution has been putting them together in a more-or-less logical format, besides modifying them enough to correct minor bugs and make them fit in the 4k space.

Its main sections are:

- Sandbox 3d (General utilities)
- Alpha/Display functions
- Math Functions
- MLDL Tool kit.

There's also a couple of multi-function functions (a la HEPAX), a handy way to go around the 64-max function limit in the ROM FAT. For these, index=000 produces a catalog of the subfunctions.

It is of course an "open" ROM, and as such its source code is also published together with the ROM file and a short quick reference guide in pdf format.

Any comments and feedback for improvement is always appreciated.

Happy playing in the SandBox!
Angel Martin


For now you can play with Angel's amazing SANDBOX in the V41 emulator... but this will change soon...

The Clonix 41 (a personal proyect) is fully operative now and will be ready to reach your 41's by Xmas.

It's a standard module size ROM, with room enough to hold five 41's pages, it's fully reprogrammable (PIC programmer needed) with the .ROM images files you like, every page in its flash ROM can be addressed to any free 4k block and supports banksitching too. Runs in Half and FullNuts, not in 2x units though.

You can merge your favourite modules to save physical ports for other peripherals/modules, and/or load your own programs and make them run into a *real* world HP-41.

To be continued...



Diego, does this will be a hardware? Can you send me some pictures?
Should this be a new Rambox? What are the advantages?



Hi all, Mathias,

I'll try to answer your question as well as provide some general info about the Clonix 41 module.

Now, when I've read my previous post I realizaed that it sounds like a commercial ad. Nothing to do with it.

So, I'm going to start telling some things my Clonix module cannot do: it has no RAM so it cannot emulate an HEPAX module or other such MLDL-like devices, you can programm the ROM code of this modules though, but the behavior is not as expected. The ROM contents of peripheral devices is also suitable to load but again you cannot espect it to work properly.

Yes it's a new piece of harware, namely a PIC microcontroller with Flash memory, it's the same idea that John Ioannidis proposed, my goal has been making it fit inside a standadr module housing, make it handle the three power status of the 41 (SLEEP, STAND BY and ON) thus drastically reducing the power requirements (by far the more dificult task of the proyect), modify the code to manage early machines (those that insert two negative pulses inside the SYNC), manage the four BANK-SWITCHING instructions, and built the hole thing in a way it can be reprogrammed trough the same connector.

Obviously the 41 cannot program flash eproms by its own means it must be made by a PIC programmer, but they a very common nowadays and fairly cheap ($10 - 15), also the required programming software is free at

It uses the same .ROM image files than the well known V41 emulator, and can hold up to five pages.

Regarding the benefits, the most obvious benefit is reducing the port usage, if you want to plug for example Advantage + CCD + Ext I/O you'll end with a single port left; but with a cClonix module you can load this configuration and still have three free ports.

You'll also can keep those expensive ROM modules in a safe place while using ROM images of them without risk. Can also load your own programs: Angel's SandBox is the best example of that. And with a little bit of imagination can even built some "impossible" configurations, Advantage + HP-IL Dev.?? You only need to change one byte (the XROM) for one module to avoid the conflict in the programmer's editor and... voi-lá, (of course you'll need to re-code the previous written programs to match the new XROM number.)...

Ok, it's starting to sound commercial-like again, sorry.

I can send you pictures of this new child, anyhow there's not too much to see, it's a module with a label that identifies it as a Clonix 41.

I'm now trying to prepare an adequate manual to properly document the programming process.

And hope to have some units available about Xmas, they'll be very few due to the lack of the module shells needed for housing. And three of them are going to be sent to my contributors (they will become -by this way- into involuntaries Beta-testers... :-), the rest will of course run at eBay.

Cheers by now.


Diego's project is a super cool addition to the 41's world. It also removes the "tyranny of the Zeproms" (lastly seen on eBay for $250 apiece), as we will be able to fit even more stuff on Clonix's !

Watch out however for uncontrolled changes to XROM id's, sometimes it isn't all that simple: the xrom id# can indirectly be part of the code within the module. I know this because it happens in a couple of functions on the SANDBOX... call it risky programming, but it saved dozens of words, and space is at a premium!



But there is a problem,
it does not work with speed-tuned HP41! I do not know about Zeproms that you mentioned. Can they be used with 2xspeed up HP41's?
I think all of you use speed-tuned HP41, it can be done so easily?


Yes, the Zeproms runs on speed-up 41's.
I made 3 PK-ROM images a long time ago (also inspired by Ken Emery's book). They were mostly in m-code, but a few programs were user-code. If I get the time to write some kind of manual, I might publish them.
As everybody else I'm thrilled about the news of better/cheaper ways of making modules. I'd like to contribute, but I'm afraid I'm not much help there.

Poul Kaarup, Denmark


Let me add to the confusion:

I have done something similar to the Sandbox, it is called the ML ROM, but not available anywhere, I used it in an EPROM box only. May post it some day. It runs fine on V41.

I am working on the MLDL2000, which will hold SRAM as well. It will hold up to 63 ROM images in FLASH and 16 ROM images in SRAM and will talk to a PC using USB. The bad news is that it will NOT fit in a module housing, but requires the shell of a card reader. It will probably support the HEPAX module.



cool project - when will your MLDL be available for us freaks? Can we afford it, i.e. how much will it cost?


Dear Diego,

your Clonix plug in solution sounds absolutely interesting, a small alternative to the powerfull MLDL unit from Meindert. What we need today are replacement solutions for Zeprom, RAM-Box (W&W or Eramco)and HEPAX, because this exotic parts are hard to find and includes absolutely high prices. Therefore any new development (plug in module or card reader case) are absolutely wellcome to the HP41 world :-)

Please Diego, open a own tread for your Clonix project - do not mix this news with Sandbox.

What HP41 enthusiasts need beside hardware storage units like the systems above, are new HP41 plug in modules and ROM-image-files, programmed in USER code - or much better in MCode.

Therefore the actual work of Angel about his SANDBOX project is absolutely nice. Please Meindert present also your solution to the HP41 world. Furthermore we hope to get the modified CCD-Module solution from Reymond Del Torno in next time :-)

Angel, please contact me about "page 2 = W&W RAM-BOX operqting system" ???

Best wisesh from Germany - Christoph Klug


It seems that there will be more than enough ROM emulators :-)

Today, I succesfully finished the simulation of my private ROMPACK emulator and I am starting to build the prototype.

My design will fit in cardreader, supports 62 4K ROMs (plus one special ROM), can coexist with original ROM modules, supports banking and draws very low current.

Maybe, there will be also an USB interface. :-)

There will be no SRAM, so the module works as a pure ROM emulator, not as MLDL.


Pavel, not more than enough! The more, the merrier...
choice is a word long ago extinct in the 41 world, it won't be bad to get it back to our vocabulary!

Angel Martin

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