HP-71B - HP-41 Translator Bits?


I can't find this particular bit pattern anywhere on Usenet or the Internet. Do any of you hard-core HP collectors have the 82490A module? Have you extracted it into a free-standing LIF or other file type? Would you consider letting me make a digital copy of that bit pattern?




FTH41ROM in J.F. Garnier's Lex Files 1 collection.


That's actually a copy of the lexfl1.gz LIF image available from the museum's FTP site.

The status of the FTH41ROM file is discussed in this museum thread. What I'm trying to do is to run EMU71 with the HP-41 translator. The referenced thread says that the FTH41ROM file is "part of" the 16K soft configured portion of the translator. Is the hardwired E0000 portion the same as the standard FORTH ROM? Also, the lex file is only 890 bytes, far smaller than 16K. WTF, over? 8)

Edited: 12 Sept 2005, 1:34 a.m.


Hi Howard! How are you?

Got the FORTH bug I see. I wish I could help you but I don't have a HP-71 to start with... Let me (us all?) know how you get on.

Interesting archive thread you pointed out.

On another subject entirely, I have a few (hardware) photos I just posted to my webpages that might just interest you. I am tinkering with my 41 on a 'scope, preliminary to getting my LSA running. One photo is interesting in that it shows what a difference twisting two short (insulated) wires together can make... ;-). The difference between crashing a 41C and seeing the data bus in actin is so very fine... In light of your earlier inquiries about HP-IL it might be interesting to you.

Just a thought.

w.r.t. your current endeavours: good luck!

Don W



I am surprised that it makes so much difference. The HP41 bus is pretty stable in my experiences. However, since the signals are CMOS, you should avoid loading them. Crashes can occur when pulling a signal too low, but I have used pretty long (non-twisted) wires to my scope or other circuits without any problem at all.
Also be aware that the ISA signal is used as a reset by driving it high for a short time.



Hi Meindert.

Thanks for the info. I have been doing a bit of reading so I know about the coconuts "soft" reset, etc.

I am not loading the buss much at all at the moment. Just a CRO:
1 Mohm || 39 pF.

Yeah, I was a bit surprised at the DATA bus crashes, too.
To be exact though, that happened on my 41CV, which is a very old
(early) machine from January 1981 production. It wuld have been one of the first to use the then new high capacity (?!) 16 x 56 bit RAM chips. Maybe they switched to internally buffered circuitry or revised the chip design shortly after that?

On my old CV I know the ROM is able to drive the ISA bus more strongly than the RAM can do with the DATA bus. There's a real difference!

Finally, to be fair to my CV it was fitted with a TIME MODULE and two other modules during the "run" where I had the crashes: X functions and a CIRCUITS ROMPACK. So there was a bit of capactive loading contributed by the modules themselves. But yes, I got the system to crash a few times...without trying ;-). The "new" 41C (manufactured September 1980!) was not fitted with any modules, so it "got off lightly", so to speak.

I had been planning to buffer the BUSS before looking further
(with a 74HC04 or a CD4069) but found I could get reliable operation just by using the transmission line approach.
So I guess we can all learn a thing or two from a simple jig, even
if we do use high density chips, SMT and CAD/CAM VHDL software!

Electronics is fascinating. I have been working with CMOS and LSTTL logic for 27 years (analogue a little longer) and I am still surprised very occasionally. The other day with my CV was another such occasion.

Don W


my 41CV, which is a very old (early) machine from January 1981 production. It wuld have been one of the first to use the then new high capacity (?!) 16 x 56 bit RAM chips.

I think you meant the new high-capacity 64 x56 bit "quad" RAM chips;
the HP-41CV uses five of those and one of the 16 x 56 chips.



Yeah, Eric, I was lost in space (tired) when I wrote that...

By the way, I think you said way back when (in a reply to me in another thread) that a USB port for the HP-41 would be good.
What's wrong with using an MLDL2000?

Would many people really just want usb alone for the 41?
What for? And what else might people want that's practical?

I was thinking a while ago about doing a very few really practical add-ons for the system, which the average engineer would use, rather than people who want a pocketable coconut assembler etc., which is in theory what some of these "power gizmos" (Diego and Meinderts marvellous hardware) would do and I guess what they are aimed at.

My interest lies in another area entirely, real add-ons and reliable repairs for everyday maths / engineering HP41 users.

Any regular (everyday real world) HP41 USERS please feel free to respond... (keep it practical if possible.)



I think you said way back when (in a reply to me in another thread) that a USB port for the HP-41 would be good.

Did I? I suppose I might have said something like that, though I don't recall. I'd personally probably be happier with an EIA-232 serial port (formerly known as RS-232), but these days most people probably prefer USB.

A serial port would be more useful to me in that it would allow the 41 to control instruments as well as upload and download software.

What's wrong with using an MLDL2000?

Nothing, other than that I don't have one, and AFAIK it doesn't allow the 41 to programmatically control data transfers to other devices.


A $20.00 USB to serial device gives you the best of both worlds.

Well, a USB port + converter is bulkier than a nice built in serial port. But I've gotten an HP-85, HP-48, HP-41, HP-75 and HP-71 talking to my T40 laptop running Linux with one of those things. (The latter three with the HP-IL<->RS-232C converter.)


Hi Howard. Yes you are right it does, MOST of the time...
USB has a few serious drawbacks in certain areas though...

I ran across your docs showing your network the other day.
Pretty cool, but what do you actually DO with it?

Not being rude, just curious. How's the long HP-IL going?



Hi, Don.

I now have two of the HP-IL/Cat-5 cables. I use both on a daily basis and they work great.

As to what I actually do with all this stuff, I'd first like to point out that getting anything accomplished with a hobby is optional, in theory anyhow.

But truth be told, I am pursuing several goals with all my HP-IL equipment. The main high-level goal is to make as much old software for the HP-41, HP-71 and HP-75 accessible to current enthusiasts as possible. That means developing or reviving systems to connect the old storage media to the 21st century Internet. It also means trying to scrape together documentation for all the old stuff that lacks it. The lack may be due to loss of original hardcopy, or perhaps because the documentation is buried in old PPC or other club journals. In either case I need to load the software onto a real machine or an emulator, figure out what it does, then try to match it up with other information sources. This is an enormous task, which I will never complete on my own. But it's pleasant to pursue at my leisure because it requires playing with the old machines and reading the old journals, which are both activities I enjoy.

In a closely related goal, I'd also like to collect and conserve as much old software and printed matter as I can. I'm standing on the shoulders of giants here, for which fact I am profoundly grateful. But I do occasionally run across old programs that aren't in any online repository I know about. I have several user library programs that fit this description. The user library probably perished in a landfill after the Corvallis division moved to Singapore, according to several threads in the museum archives. It seems to me to be worthwhile to try and reconstruct as much of it as we can from the materials that were distributed by the library over the years.

I'm also interested in writing a Linux HP-IL driver. I got some way down this path before I realized I could run EMU41 and drive Cristoph Klug's ISA card under Linux without a driver. That removed a lot of the incentive to write the native driver. So I've been lazy about that.

And generally, I have fun with systems. The HP-41 is an open system, rather than a closed box. I didn't know that when I bought my first one from tutoring money in Junior College, but that's what it was, and is. The other machine I got introduced to then was the Apple II, another open system. Those two open platforms were products of the accelerating advance of microelectronics that swept through the last third of the 20th century. And they were my entry point into that tide of change and progress. So being able to connect them to the 21st century isn't just a cute trick in my opinion. It's really a profound reflection on the nature of open systems, as well as a personal journey through my own history.


Another great answer, Howard.

I dig it, brother...




Thanks for the feedback Eric.

Yes, I thought rs232 is better. USB being block sucks a fair bit for control type apps. The data rate is total overkill for the 41.

I will try to roll a nice simple 232 adaptor for the 41. Don't know when but in next month or three...

Do you have an e-mail address where I can ask you about software control of 232 port data lines etc...? If you don't mind down the track I would love to be able to get a few answers from someone who's actually done it, because I would be using the port in a higly non-standard manner... you know what I mean.



Let me add my comments why I have done USB instead of RS232 in the MLDL2000. I agree that RS232 is better because it is on almost every type of computer. The problem is that a controller or CPU is required on both ends for RS232, andthe latest notebooks do not have RS232 anymore. The USB solution in the MLDL2000 allows a much easier implementation on the MLDL side, and the selected USB device (FT2232C) gives me instant communication with the CPLD by allowing bitbanging from the PC.
Eric is totally correct that it does not allow control of devices from the HP41, and indeed, that is not possible with USB, and that was not intended. In order to allow control, microcode or usercode is needed on the HP41 and I wanted a device with no specific microcode requirements. The USB on the MLDL2000 is mainly intended to transfer data between the 41 and the other computer (ROM images and control of settings) and later (still need to make some software for that) to do higher level control, like having the PC emulate mass storage, printer and such stuff.



Hi Meindert,

Yes, I understand why you chose usb and did it really well, too.

I have just looked at your manual for the mldl2000 or maybe the specs, not sure?

Man, you have done one class A1 job on that hardware design of yours. It really is a very very nice implementation. When I think of the amount of work you put into that, including the documentation, and the time that it all took I am really quite amazed.

I have done a little real engineering work for clients with
say a breadboarded SBC which was hairy as a goat but ran, non optimized, which they wanted a PCB cut for.

Too much detail, way o.t. and boring to most to go into here.
But there was a lot more to that story including on-the-fly design corrections to debug their circuit with no possiblility to test the mods, and a very tight design / fabrication schedule. For example, I had to learn PROTEL advanced schematic and PCB in about one month flat... My point being that I have an idea of the work involved in your project.

Very well implemented and documented, Man!




errata to your post:
4 x 64by56bit + 1 x 16by56bit (not 5x64x56b + 1x16x56b),
[I have one...]

Whose counting? This stuff is so small in capacity that no wonder I got confused. I have always really been annoyed that HP provided
so little RAM. The system was very old, but they could have at least furthered the series of RAM to give a factor of (at least) four times the CV memory. Otherwise a really great product.


No, the 41CV definitely has five of the 64x56 and one 16x56. Otherwise how would you get 320 registers (319 as described by HP, due to three bytes consumed by the final .END.)?

Maybe you've overlooked one because it's on the other end of the board with the ROMs.

The original 41C had only five RAM chips, all 16x56. The 41CX has eight; the same six as the 41CV plus two more 64x56 to add the built in extended memory (128 registers, 127 as described by HP due to one being consumed by housekeeping).


Edited: 13 Sept 2005, 7:06 p.m. after one or more responses were posted


I think I am getting confused between the new C I just got,
(mucking around with that till my eyes go funny...) and my old
CV (now safely together again, not coming apart unless it has to, etc...)

So yeah, Eric, I need more sleep...

You programmers are always SO picky... ;-)


P.S. had a look at your pages somewhere. Hey, you have written
a bit of code, haven't you? Cool...


P.S. had a look at your pages somewhere. Hey, you have written a bit of code, haven't you? Cool...

Lots of little things, a few almost-medium-sized things. The only big programs I've worked on have been commercial programs where I was only responsible for a few portions.

Some day, when I win the lottery*, I hope to spend a lot more time on writing free software.


(*) By which I mean stock options, not the state-run lottery. I almost never participate in the latter, since it's normally negative expectation.

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