HP-71X: HP-71B MicroCode Emulator for HP-48GX (Preliminary Info)


After many months of research and development I have a fully functional and working beta version of HP-71B Micro Code Emulator. Currently it is running on HP-48GX with one 128K memory card but it will be ported to HP-49G in the near future.

For the first time it is possible to write real HP-71B BASIC programs on HP-48. Perhaps it will be possible to write Forth and Assembler programs in the future, too.

There is just one picture of the emulator running on Emu48 under Windows on my homepage (http://hrastprogrammer.tripod.com) at the moment.

The emulator is based on the original HP-71B ROM so it behaves almost *exactly* like the real calculator with just a few differences caused by the different hardware. The screen looks the same and the HP-48 keyboard is accomodated to act like the HP-71B keyboard. Although the HP-71 display is 132 columns wide, the last column is rarely (if ever) used but, if needed, scrolling can be implemented in order to see all 132 pixels on the HP-48 display. And because the HP-71 keyboard has 55 keys and HP-48 keyboard has only 49 keys, some HP-71 keys have to be shifted with the additional shift key (I use Alpha key for this purpose).

It is very easy and joy to use the emulator on HP-48. Available memory is increased to 33.5K and can be increased to the maximum of 161.5K if needed. The emulator is about 3x faster than a real calculator.

In the current state the emulator isn't suitable for the public distribution so there is a lot of work left in this area. And, of course, a lot of testing, testing and testing ... Things which aren't working at the moment are annunciators and TIMER2. TIMER3 won't be supported because the third timer doesn't exist on HP-48. Anyway, TIMER3 isn't used too much in the HP-71 ROM, except for just 2-3 occasions which can be emulated in a different way. And keyboard repeat is very slow at the moment and this has to be improved but I don't know how. There are some problems caused by the TIMER1 resolution which is just 4 bits on HP-48. For this reason the DELAY is different than on the real HP-71 (0<=DELAY<=1 is the same, 1<DELAY<8 acts like DELAY 1 and DELAY>=8 is the same).

Another things which I plan to implement include MATH, Forth and HP-41 Translator ROM support. Perhaps another ROMs cane be supported (like JPC ROM) - I don't know at the moment.

If you want to get a demo then, please, send me a mail. If I got enough mails I will make a demo and send it to everyone who requested it. After this, if there would be enough interest I will make a full version. Details will be presented on my home page.

Best regards



So it's the second HP-71B emulator (AFAIK) after my Emu71 for DOS ...

Of course, I would be pleased to test it!

I plan to improve my own emulator ...




Pls think about a switch for monochrome displays (HP200LX) when enhancing your emu71.



Hi Jean Francois,

I'm often using your new EMU41 with HPIL PC card support. I'd love to see EMU71 supporting the HP82973A as well. The HP41 and HP71 always were my two favorite machines to control measurement equipment.

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