HP82494 HP71B Survey Module



I asked this question a few months ago but got no answer. Maybe I am luckier these days.
I am looking for a short summary of the functions this module offers. Some things I discovered myself but I am not a surveying engineer so I miss some information. A scan of the manual will although be nice because it is not in the museums files.

Best regards



82494 is the model number of a Custom ROM Module. A while back, I posted some information about custom modules from a 1986 HP catalog:


For information beyond this, the catalog said HP would refer you to third-party software developers who would help you get your application into a custom module.

Try SHOW PORT, it should give the size of the device in the port and the number 2 indicating it is a ROM. 82494 should be a 64K (size 65536) ROM.

I think these were mask ROMs, not programmable ROMs - I think HP would assign a unique model number when a customer's module went into production. Maybe the A or B suffixes indicate EPROM vs. mask ROM. Maybe what you have is a pre-production copy of the module. Try to get a listing of the files in the module with CAT :PORT(n) and post that here. Someone might recognize the module from the file names.


Hi Ellis,

thank you for the information.
I think that it is a masked ROM (64k), too, but I didn´t know that these were made avialable by a 3rd party developer.

The exact text on the back of the module shows: "82494 REV 0 SURVEY 1 of 1 SINGAPORE". This seems to be the standard HP label.

The ROM contains some BASIC-files which are protected. If I could find a way to read them my problem is solved.


When I start "SURVEY" I get a table to choose the desired algorithm or program. But I am not enough of a surveillance engineer. I only unterstand the AZDIST and GEOUTM programs (by the help of a nice book about field surveillance techniques) but the parameters of the other programs are unknown.

Best regards



I didn´t know that these were made avialable by a 3rd party developer

I'm sure HP made the ROMs, but the catalog says this:

"Custom Products and Programming Development Aids
Through customization, the powerful HP-41, HP-71, and
HP-75 can be tailored with your own software to perform
the functions that will increase performance productivity.
Using customer- or third-party written programs, the
HP-41, HP-71, or HP-75 can be customized using Custom ROMs,
EPROMs, Magnetic Cards, and Keyboard Overlays. The HP-41
can also be customized with Custom Keyboard Touchpads and
Bar Code.
The services of Independent Custom Consultants (ICCs)
make the customization process easy. (A list of ICCs is
available from your HP Sales Representative.) ICCs are
application-oriented software houses with in-depth training
on HP products and system integration. They convert
software to finished Custom Products and can write and
field test software, package the system, write user's
manuals, and more. Choose and contact an ICC to help you
decide if customized HP products can be used to help meet
your needs."

So a company specializing in surveying, for instance, could have a ROM made without having their own in-house HP computer software development people.

The reason I think it might be a third-party module is because I would guess that HP would have assigned a unique model number, even in pre-production. BTW, I looked in the same 1986 catalog and found that HP did have a surveying module for the HP-71B, model number 82483A. The catalog has no details other than the model number and its manual isn't on the Museum CD-ROMs. Maybe what you have is a pre-production (judging by "REV 0") release of the HP 82483A.


Hello Ellis,

thank you for your help. I took some interesting facts from your posting. So I decided to modify the header - perhaps someone has some hints on the other module. I think there is a chance that the contents of these two are not too much different. I have looked at the manual of the HP41´s survey module and the HP97´s handbook but these two only gave me some hints on the used algorithms. The HP71 has a more comfortable user interface.
I made a picture of the module. The printed letters and the case look exactly like that on my HP-4k-module. As I remember the real 3rd-party-modules have a different character set for the label.
When I pulled it out I found an additional description on the back (my fault, should have looked before...) :

104 001 120 2 HTI



Best regards



Hello Stefan,

here is a link to an US army site which contains documentation to the system this ROM belongs to:


The complete system was called BUCS (BackUp Computer System).
I got mine together with a ROM called DDCT installed in a HP-71, and the web site mentions the SURVEY ROM also. If You should find the manual for the surveying ROM there, please post the link.
The HTI SURVEY ROM is completely different from the HP survey ROM.
There are other army related HP-71 ROMs, seems that the US army bougt a lot of hp-71 stuff.



Hello Peter,

thank you - that was indeed the information I was looking for. Now some things become clear because some parts of the program didn´t look like made for terrestical navigation for yachting or general surveying.

The documents you mentioned contain a good description of the theoretical background.
Chapter 12 contains a description of the programs. It is not like a manual but some hints to the experienced user. They often refer to some military standard paper forms to copy the values.

After reading it all I will write a short paper with the descriptions for the forums data base. But that will take some time, it´s a lot to read.

Bst regards


Possibly Related Threads...
Thread Author Replies Views Last Post
  HP71B Spy Radio Crypto Donald Ingram 2 999 10-14-2013, 10:51 AM
Last Post: Eric Smith
  HP71B to HP 41 Translator ROM Manual Michael Lopez 5 1,273 04-25-2013, 03:51 AM
Last Post: Mike (Stgt)
  Rather large missed opportunity - a pile of HP71B's Chris Smith 3 903 04-19-2013, 07:30 AM
Last Post: Chris Smith
  HP 41CX Survey Pac Keith Burr 7 1,548 03-29-2013, 10:09 AM
Last Post: Keith Burr
  HP-41C Custom Survey Module Identificaiton Help Dan Grelinger 0 548 01-27-2013, 01:51 PM
Last Post: Dan Grelinger
  Has anyone else had problems with ebay member 'hp71b'? Dan Grelinger 6 1,302 01-26-2013, 09:33 AM
Last Post: aurelio
  Error Message/Procedure HP-48SX with TDS Survey SX card bporter101 6 1,156 12-10-2012, 10:18 AM
Last Post: bporter101
  Curious SINPLOT behavior on HP71B Christoph Giesselink 4 978 07-12-2012, 03:12 PM
Last Post: J-F Garnier
  New HP71B emulation (go71b) Olivier De Smet 9 1,901 06-26-2012, 10:25 AM
Last Post: Jerry Raia
  Survey: Best programming language for next-gen HP? Oliver Unter Ecker 32 4,861 06-06-2012, 03:22 PM
Last Post: David Hayden

Forum Jump: