HP 71B ROM module CMT71-64E

HP 71B ROM module CMT71-64E: I just acquired an HP 71B with this module. It has a sticker on it saying "Copyright 1987 Topcon Instrument Corporation of America." Anyone with information on this?



I have never heard of such a module. Have you tried
to CAT the port where it is sitting to see what it
has? It may have BASIC programs with a few comments.
How about making a ROM dump available for examination?


These CMT modules were used for custom made ROM (EPROM) images.

I've never heard of TOPCON before.
Seems they didn't have a large production run... in this case they would have used ROMs.

There was a special burner for the CMT front port EPROMS... the HHP card reader EPROM modules were better, they used "normal" DIL EPROMS, which sat in a socket.

Don't even think of erasing yours, you might end up with a useless piece of junk (without the special burner).


Dan Ratcliffe of TOPCON may be able to help you. He used to be involved with their HP-71B products. He may be able to answer your questions. His number is 1-800-223-1130 X-291


From the Instructions Manual: Both the CMT-71 RAM and the CMT-71 EPROM Module plug into the front ports of the HP-71B. You can use any combination of CMT-71 RAM, EPROM, HP RAM or HP ROM Modules in these ports. ...
While the CMT-71-32R Modules provide an extension of the HP-71B RAM, the CMT-71-32KE and the CMT-71-64KE are used to store customized application programs. ...
Corvallis Microtechnology, Inc.
Grant Plaza
895 NW Grant Ave.

This is what I found in the instruction sheet.
There is no information about programming, or the data structures needed to put basic or lex files into it.
Just thinking about the same problem with a Hand Held Products HHP 71M/M, 64K RAM/32K EPROM. This is the card reader slot module. It has a DIL socket for a standard 256kbit EPROM, which I could easily programm on my PC, but I would need information how to prepare the programs.
BTW: I have three of this modules, and would trade one or two for other HP-71 accessories. (No, not for a 4k RAM module...)
Is it possible to copy an existant module, like the data acquisition ROM, to this eprom? How to read the data from the ROM?



I also have a hand-held products 71MM 32K EPROM module
with some custom-programmed stuff. I just opened and,
sure enough, there is an HN27256G-25 standard EPROM
in there. There is also a jumper; does anyone know
what it is for?

As for downloading the contents of a module, well,
you can use something like this:

20 DIM A$[64]

30 A=HTD("00000") ! rom base address

40 L=64 ! length in KB

50 FOR I=0 TO L*32-1

60 A$=PEEK$(DTH$(A+I*64),64)

70 ! print A$ to your preferred output device here


To find the base address of a module, just do
ADDR$("filename"), where filename is the name
of the first file in that module; you'll get
the base address of the module plus eight.
The program above will print hex for the computer's
internal ROM. Disclaimer: program is basically
the same as that used by J.F. Garnier to extract the
firmware off HP71's for use in his emu71 emulator.

Note that if the ROM contains PRIVATE files, you will
have to use a version of PEEK$() that allows you
to look into those files; the one in the HP71 BASIC
doesn't let you do that. I know that there is a LEX
file somewhere (probably in the jyu archive) that can do it.

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