Non-Prime question alert: Hp-41 and synthetic instructions


A few days ago I got an HP-41CX. I'd never used an HP-41(or an emulator) before. The advantage and IR modules are in the mail.

I've been playing around and trying out some of the programs in the library and have a question.

Right now I don't have the time or interest in learning about the synthetic programming. Maybe some other time. However, some of the programs in the library use some synthetic instructions ('STO M', for example, is a common one).

I've poked around and while there is lots of material on synthetic programming, all I really want is simple documentation on how to enter some of these instructions when I encounter them. I have not been able to find that.

Can someone point me in the right direction. I am looking for a simple how-to, rather than in depth information.



Instead of M and N you can use any unused regular registers, such as 00 and 01, for instance.



Instead of M and N you can use any unused regular registers, such as 00 and 01, for instance.
Generally yes, but some of the lettered registers were used for Alpha manipulation, too, so it depends on the target of the program.

The easiest and best way to enter synthetics is the W&W CCD Module, or an image of the CCD Module in a RAM/ROM simulator module. As an alternative I'd recommend the CCD OS/X , which contains all operating system extensions and nearly all I/O functions from the CCD module.




Well, I did poke around some information on the CCD module and also read this

It appears that it is definitely not quite as simple as just punching in an undocumented key sequence. I will spend more time on it sometimes in the future and in the meanwhile stick with Gerson's advice with regards to M&N and stay away from other synthetics until I have time to learn a bit more.

I must say that I do enjoy the calculator. I must be one of the few people who got familiar with the WP-34S before ever having touched a 41 or 42. Now I am beginning to understand why the 34S is the way it is ;)!


"Non-Prime question alert"

.. what a breath of fresh air :-)


Indeed, I guess we're being "primed" whether we like it or not...



I'm with you, guys!


Ready for Prime time... ;)


Ready for Prime time... ;)

There is only one real (tm) Prime computer: This one.


used such a beast at university back in the Eighties.

Edited: 4 Nov 2013, 2:15 p.m.


You cannot key in synthetic instructions just as you do with regular '41 commands. These commands are, well ...synthetic. ;-)
Which essentially means that you are dealing with byte sequences that usually cannot be entered at all. The regular 41 operating system prevents the user from doing so.

Here's an example: STO N is byte code 91 76. You can press [STO], but there is no way to have it followed by an N. However, you can enter RCL IND 17 followed by LastX. In hexadecimal byte notation, this is 90 91 76. Now you just have to remove the first byte (90) somehow (e.g. with the fabulous "byte grabber"). This leaves 91 76 - et voilà, there is your STO N. It was synthesized from two other commands.

As you can see, you will need at least two things: first, a HP41 byte table (available on the internet), and then a means to remove single bytes, e.g. the mentioned byte grabber. You should find some instructions on this site on how to make one.

You may also completely ignore synthetic programming. Using registers M, N and O in some programs often simply is a way to acquire a set of temporary registers. M, N, O and partially P usually hold the contents of the 41's alpha register. So a simple CLA clears them all at once, and if a program does not use the alpha register, you get three or four registers for free, even with SIZE 000 set. Which is very handy but not the only possible way. Simply replace these registers with regular numbered ones, and you are done. On the other hand, if you really come across a synthetic program that uses these registers in a more sophisticated way, or does even things that cannot be done with standard programming, you will have to dig much deeper into the world of synthetic programming. Which means: get a book and take your time.



That is the most succinct and clear explanation of synthetic instructions yet!

I think that I will ignore synthetic programming for now. The regular instructions is definitely rich enough to entertain me.



The ZenROM also provides easy entry of synthetic program lines.

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