HP-71B Forth Module

I've been searching with Google to try to find out as much information about Forth on the HP-71B.

I keep stumbling across the following two Module part numbers:


Both of which seem to be linked with the Forth module.

Given how unlikely I am to find one, and then afford it (!), can anyone enlighten me as to which of these I should try to find in order to use Forth on the HP-71B?




You want to get HP-41 Translator Pac for the HP-71 (HP 82490A) or HP-71B Forth/Assembler ROM (HP 82441A). Both can be run under EMU71 emulation and the docs can be had on the MoHPC DVDs. I cannot tell you if the FORTH is exactly the same or not on both. I think it is.

I use the HP-41 Translator Pac for the HP-71 (HP 82490A) on my 71B as well as in EMU71.

Some of my 71B FORTH Pi Programs (if you are interested):




HP 82478A - Debugger for the HP-71: Simulator of assembly language

Provided as LEX files to be copied into RAM from mass media.

HP 82441A - Forth/Assmbler ROM: Development environment in Forth/Assembler. Provided as (hardware) ROM.

The debugger may work as a kind of expansion of the Forth/Assembler ROM, but the ROM is what you are seeking for.

If you want to play with it you should use Emu71 and the emulator-based ROM. Visit Christoph Gie├čelink's and Jean-Fran├žois Garnier's pages.


I can't tell you the differences between the two, but I have the 82441A Forth/Assembler module, and I will comment that it is a really lousy implementation of Forth. I can't believe how slow many of the Forth words are. But, being Forth, it allows you to raplace words with your own definitions and speed them up. Re-writing many of them in Forth as secondaries, ie, without even using assembly and writing primitives, I was able to improve their speed by a factor of anywhere from two to fourteen! (CHR$ was the one I made 14x as fast.)

Edited: 3 Nov 2011, 11:27 a.m.


You want to get HP-41 Translator Pac for the HP-71 (HP 82490A) or HP-71B Forth/Assembler ROM (HP 82441A). Both can be run under EMU71 emulation and the docs can be had on the MoHPC DVDs. I cannot tell you if the FORTH is exactly the same or not on both. I think it is.

You're wrong, Egan, the FORTHs are distinct and what's worse, incompatible.

All in all, I'd rather have the FORTH/Assembler ROM than the HP-41 Translator Pac because I see no real use nowadays for HP-41 programs translated to run in the HP-71B while using the Assembler to create and compile your own binary subprograms, FORTH primitives, and custom LEX keywords still holds some magic.

Best regards from V.


the FORTHs are distinct and what's worse, incompatible.

Thanks for the clarification. As far as I could tell from the documentation the FORTHs are the same. All I could find:

So the FORTHs are source compatible and the same in that sense.

Edited: 3 Nov 2011, 4:22 p.m.


The FORTH/Assembler ROM is definitely great - especially the SATURN manual that was included.

I used it to disassemble the 48SX ROM initially.


Some month ago I also gone through the Internet searching for HP71B ROM module numbers. That's what I found about this:

HP 82441A was the number of the first Forth/Assembler ROM. This package did not contain the Debugger LEX files. Later the Forth/Assembler ROM was republished with the Debugger LEX files and new package got the number HP 82478A.

At this time I made a cross reference list with all HP ROM module numbers and labels I found:

Number cross reference list

HP 82441A HP-71 FORTH ASSEMBLER (without Debugger)
HP 82478A 5061-7234 HP-71 FORTH ASSEMBLER
HP 82479A 5061-7290 DATA ACQ
HP 82480A 5061-7226 HP-71 MATH
HP 82481A 5061-7237 AC CIRCUIT
HP 82482A 5061-7239 FINANCE
HP 82483A 5061-7238 SURVEYING
HP 82484A 5061-7241 CURVE FIT
HP 82485A 5061-7240 TEXT EDITOR
HP 82488A 5061-7271 DATA COMM
HP 82489A 5061-7270 AMPI STATISTICS
HP 82490A 5061-7269 HP-71 41 TRANSLATOR

If somebody may recognize a mistake in the list above, don't hesitate to correct me.



Hmmm that means I got the second version of the Forth/Assembler ROM but unfortunately I did not get the debugger LEX files.


With the magic of Google Newsgroup archive, the original announcement of the Forth/assembler debugger on net.micro.hp is still available on-line 25 years later:

HP-71 FORTH/Assembler Debugger .

Edited: 4 Nov 2011, 3:33 a.m.

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