HP-71B and some (to me) interesting modules

[JanS]

I recently aquired an HP-71B in quite good condition "by accident" (I was buing a 48 from somebody dispensing with parts of their late fathers estate). The person selling the 48 had some other HP Hardware they were willing to add to the sale for very little over the price of the 48 and not really knowing what I was getting into, i closed that deal. So, the 71B in Question did not come with the HP Card reader (but a CMT Memory Module in it's place), a case, a power supply or anything other than what was plugged into it. Also, someone had the good notion of not leaving batteries in it, so no leakage !

Once home, I put fresh batteries into the machine and powered it up - That's when I got a little bit of a surprise:

   

I powered the machine back off, read up on the compendium and unplugged everything from the machine to document what i got:

This is what I found in the 4 front ports:

Corvallis 64K RAM Module
CMT71-64E Eprom Module
CMT71-32E Eprom Module
HP-71 Forth Assembler 5061-7234 (HP-82478A FORTH/Assembler ROM with Debugger)

   

On the back of the machine, I found:

HP-IL Interface 82401A
CMT Memory Module CR-128R

   

I don't really know what the W&W Software in those two EPROMS does, but for the time beeing, here's what I've been able to find out so far about the machine and it's different parts:

VER$ Output:
HP71:2CDCC HPIL:1B FTH:1A EDT:A KBD:B W&W:A CSTU:A CSTU:A EDT:A DATA:B

SHOW PORT Output:
0.05 16384 2
1 16384 2
2 65536 2
3 32768 2
0 4096 0
0.01 4096 0
0.02 4096 0
0.03 4096 0
4 32768 0
4.01 32768 0
5 32768 0
5.01 32768 0
5.02 32768 0
5.03 32768 0

As the memory modules in Ports 1 and 5 are RAM and have been without power for years and the Forth Rom in Port 4 is a known, i did not bother to look at them, however here is some more information for the two EPROM Modules present in Port 2 and 3:

I did a CAT:PORT(2) and this is the output of that command:

BABEIN BASIC 5080 10/09/89 18:17 2
BABDRUCK BASIC 7746 10/09/89 18:17 2
BABPVGL BASIC 9082 10/09/89 18:17 2
LFGEIN BASIC 2769 10/09/89 18:17 2
CAT BASIC 2583 10/09/89 18:17 2
LFGWOCHE BASIC 1057 10/09/89 18:17 2
LFGKBE BASIC 6848 10/09/89 18:17 2
LFGWOEIN BASIC 3955 10/09/89 18:17 2
LFGPLOT BASIC 4108 10/09/89 18:17 2
VKEIN BASIC 3820 10/09/89 18:18 2
VKQDRUCK BASIC 4554 10/09/89 18:18 2
VKMDRUCK BASIC 3566 10/09/89 18:18 2
VKJDRUCK BASIC 4073 10/09/89 18:18 2
LKT BASIC 1756 10/09/89 18:18 2
SICHERN BASIC 1109 10/09/89 18:18 2

I did a CAT:PORT(3) as well and here is the output of that command:

WUWROM1L E LEX 10822 10/09/89 17:22 3
KABULEX LEX 9382 10/09/89 17:22 3
EDTEXT BASIC 6790 10/09/89 17:22 3
EDKEYS KEY 54 10/09/89 17:22 3
INDEX2 BASIC 1838 10/09/89 17:22 3
SODI BASIC 1670 10/09/89 17:22 3
UPRI LEX 105 10/09/89 17:22 3
PRINT BASIC 1424 10/09/89 17:22 3

So, naturally the W&W EPROMS have me interested. I'm in the process of aquiring a PIL-Box from Jean-François (if still available - I just emailed him today) to interface with one of my PCs for the purpose of learning and having something new to play with something old (and possibly preserving the ROMs along the way as suggested by Bob Prosperi).
I've also emailed Wilfried Kötz, who I believe is the (former?) owner of W&W to see what he has to say about these ROMs.

I also did disassemble the CMT Memory Module that was in the card reader port to check it's battery - no joy - so I need to find a replacement cell, some new heat shrink to seal the new cell once I get it soldered into place and some time to actually do the work....

   

I guess for the 64K RAM Module in Port 1 there are no replacement batteries to be found (at least according to some of the forum entries here on the site - or has someone managed to find out a solution to that problem ?) - so I guess the PIL-Box becomes even more important if I decide to play around with the 71B for any length of time as the main batteries will at some point run dry and then whatever is in that RAM Module will be lost AFAIK. Not an issue at the moment though, because there is nothing there to begin with.

This about wraps up what I know about the machine that I lucked into.

Here is another pictures of the CMT Memory Module from the card reader slot:

Module Open:
   

Once I learn more about this machine and make progress with getting it hooked up to my PC, I'll post an update here. In the meantime:
Stay healthy and keep calculating,
Jan

[KeithB]

Congratulations! It looks in beautiful shape!

[Maximilian Hohmann]

Hello!

Interesting find. This must be about as much memory as one can fit into an HP-71B!

My first association with "W&W" and "VRB" is "Wüstenrot & Württembergische" and "Volks- und Raiffeisenbanken". The first two are a building society and an insurance company in Stuttgart, Germany, the latter a group of banking cooperatives in Germany.

The computer could have been used to calculate finance and insurance schemes for customers. During the 1980ies a lot of small computers, especially less expensive ones like the Ti-74 and some models from Sharp, were used for this purpose with specially made ROMs. Until some years ago one could still find them on flea markets and eBay in Germany (especially the ones from the "Allianz" insurance company were in plentiful supply). This would be the first time I see an HP-71B used for that purpose as it was ridiculously expensive in Germany and certainly not something a company would hand out to their average insurance agents.

What stands against my theory however is that "Wüstenrot" and "Württembergische" were only fusioned to form "W&W" during the 1990ies and this module dates back to 1986. But who knows, maybe their marketing was joined earlier?

Regards
Max

NB: Don't bother to look for a card reader for this machine. Even if you can find a working one (without selling your car for it) the cards are almost impossible to find. And if you are lucky enough to get a reader and card(s) you will discover that using it is a very major nuisance because the hand operated cards need to be pulled through the reader at a very constant speed (which I am able to achieve maybe one time out of ten attempts).

[Sylvain Cote]

(08-23-2022 01:47 PM)Maximilian Hohmann Wrote:  NB: Don't bother to look for a card reader for this machine. Even if you can find a working one (without selling your car for it) the cards are almost impossible to find. And if you are lucky enough to get a reader and card(s) you will be discover that using it is a very major nuisance because the hand operated cards need to be pulled through the reader at a very constant speed (which I am able to achieve maybe one time out of ten attempts).

I often use the card reader with 9 out of 10 success ratio. But in order to get that success rate, I need to clean up my magnetic cards once in a while. (Magnetic Card Questions Thread)

[Maximilian Hohmann]

Hello!

(08-23-2022 02:06 PM)Sylvain Cote Wrote:  I often use the card reader with 9 out of 10 success ratio. But in order to get that success rate, I need to clean up my magnetic cards once in a while. (Magnetic Card Questions Thread)

I know that thread, but it doesn't help with my cards. Maybe they just have been magnetised and de-magnetised too often? Among my four or five HP-71Bs there is only one with a card reader and I only have very few cards to play with. Anyway, there are next to no cards left to buy and if so at prices that make my eyes water. Not even if I win the lottery will I support this kind of madness!

Regards
Max

[KimH]

Oh my - you have clearly made a good buy here - this is the king of configs! Congratulations!!

I have replaced the battery in all my CMT Card Reader "ports" - not a big challenge if you know how to handle a soldering iron (and watch polarity - obviously) - they can be bought in all sorts of sizes - mine are smaller than what was in there, with wires welded on them AND has the "Heat Shrunk" cover. about 3€ a piece "Dell BackUp Battery" is printed on them

The flat battery for the 64k I also have - it still has a voltage (I took it out and stored it) - I think the right expression is "Unobtainium".. have not found anything to replace it.

Interesting to see what W&W has made for the unit - maybe they respond. If they do, I'd be delighted to hear about it. It does indeed look like something financial.

(08-23-2022 08:25 AM)JanS Wrote:  I recently aquired an HP-71B in quite good condition "by accident" (I was buing a 48 from somebody dispensing with parts of their late fathers estate). The person selling the 48 had some other HP Hardware they were willing to add to the sale for very little over the price of the 48 and not really knowing what I was getting into, i closed that deal. So, the 71B in Question did not come with the HP Card reader (but a CMT Memory Module in it's place), a case, a power supply or anything other than what was plugged into it. Also, someone had the good notion of not leaving batteries in it, so no leakage !

Once home, I put fresh batteries into the machine and powered it up - That's when I got a little bit of a surprise:



I powered the machine back off, read up on the compendium and unplugged everything from the machine to document what i got:

This is what I found in the 4 front ports:

Corvallis 64K RAM Module
CMT71-64E Eprom Module
CMT71-32E Eprom Module
HP-71 Forth Assembler 5061-7234 (HP-82478A FORTH/Assembler ROM with Debugger)



On the back of the machine, I found:

HP-IL Interface 82401A
CMT Memory Module CR-128R



I don't really know what the W&W Software in those two EPROMS does, but for the time beeing, here's what I've been able to find out so far about the machine and it's different parts:

VER$ Output:
HP71:2CDCC HPIL:1B FTH:1A EDT:A KBD:B W&W:A CSTU:A CSTU:A EDT:A DATA:B

SHOW PORT Output:
0.05 16384 2
1 16384 2
2 65536 2
3 32768 2
0 4096 0
0.01 4096 0
0.02 4096 0
0.03 4096 0
4 32768 0
4.01 32768 0
5 32768 0
5.01 32768 0
5.02 32768 0
5.03 32768 0

As the memory modules in Ports 1 and 5 are RAM and have been without power for years and the Forth Rom in Port 4 is a known, i did not bother to look at them, however here is some more information for the two EPROM Modules present in Port 2 and 3:

I did a CAT:PORT(2) and this is the output of that command:

BABEIN BASIC 5080 10/09/89 18:17 2
BABDRUCK BASIC 7746 10/09/89 18:17 2
BABPVGL BASIC 9082 10/09/89 18:17 2
LFGEIN BASIC 2769 10/09/89 18:17 2
CAT BASIC 2583 10/09/89 18:17 2
LFGWOCHE BASIC 1057 10/09/89 18:17 2
LFGKBE BASIC 6848 10/09/89 18:17 2
LFGWOEIN BASIC 3955 10/09/89 18:17 2
LFGPLOT BASIC 4108 10/09/89 18:17 2
VKEIN BASIC 3820 10/09/89 18:18 2
VKQDRUCK BASIC 4554 10/09/89 18:18 2
VKMDRUCK BASIC 3566 10/09/89 18:18 2
VKJDRUCK BASIC 4073 10/09/89 18:18 2
LKT BASIC 1756 10/09/89 18:18 2
SICHERN BASIC 1109 10/09/89 18:18 2

I did a CAT:PORT(3) as well and here is the output of that command:

WUWROM1L E LEX 10822 10/09/89 17:22 3
KABULEX LEX 9382 10/09/89 17:22 3
EDTEXT BASIC 6790 10/09/89 17:22 3
EDKEYS KEY 54 10/09/89 17:22 3
INDEX2 BASIC 1838 10/09/89 17:22 3
SODI BASIC 1670 10/09/89 17:22 3
UPRI LEX 105 10/09/89 17:22 3
PRINT BASIC 1424 10/09/89 17:22 3

So, naturally the W&W EPROMS have me interested. I'm in the process of aquiring a PIL-Box from Jean-François (if still available - I just emailed him today) to interface with one of my PCs for the purpose of learning and having something new to play with something old (and possibly preserving the ROMs along the way as suggested by Bob Prosperi).
I've also emailed Wilfried Kötz, who I believe is the (former?) owner of W&W to see what he has to say about these ROMs.

I also did disassemble the CMT Memory Module that was in the card reader port to check it's battery - no joy - so I need to find a replacement cell, some new heat shrink to seal the new cell once I get it soldered into place and some time to actually do the work....



I guess for the 64K RAM Module in Port 1 there are no replacement batteries to be found (at least according to some of the forum entries here on the site - or has someone managed to find out a solution to that problem ?) - so I guess the PIL-Box becomes even more important if I decide to play around with the 71B for any length of time as the main batteries will at some point run dry and then whatever is in that RAM Module will be lost AFAIK. Not an issue at the moment though, because there is nothing there to begin with.

This about wraps up what I know about the machine that I lucked into.

Here is another pictures of the CMT Memory Module from the card reader slot:

Module Open:


Once I learn more about this machine and make progress with getting it hooked up to my PC, I'll post an update here. In the meantime:
Stay healthy and keep calculating,
Jan

[KimH]

Forgot to add this.

AFAIR - W&W was Wilfried Kötz & Wolfgang Baltes who - back in the day - made and sold SW & Accessories (like CMT/HHP etc) for HP Calcs mainly in Germany.

If I don't have my wires crossed, one of them ended up as the product lead for the HP 27S in Corvallis, I believe the latter.

[Sylvain Cote]

Hello Max,

(08-23-2022 02:57 PM)Maximilian Hohmann Wrote:  

(08-23-2022 02:06 PM)Sylvain Cote Wrote:  I often use the card reader with 9 out of 10 success ratio. But in order to get that success rate, I need to clean up my magnetic cards once in a while. (Magnetic Card Questions Thread)

I know that thread, but it doesn't help with my cards. Maybe they just have been magnetised and de-magnetised too often?

I am surprised, but it can happen.
It seems that I am lucky, out of my several hundred of 71/75 cards and several thousands of 65/67/41 cards, very few became bad.
All had at some point oxidation or dirt, but alcohol and/or Staedtler Mars Plastic pencil eraser solved the issue.

(08-23-2022 02:57 PM)Maximilian Hohmann Wrote:  Among my four or five HP-71Bs there is only one with a card reader and I only have very few cards to play with. Anyway, there are next to no cards left to buy and if so at prices that make my eyes water. Not even if I win the lottery will I support this kind of madness!

Yeah, magnetic cards are expensive, I have paid (USD) between $0.50 and $1 per card for 65/67/41 model and between $1 and $2 per card for 71/75 model, when they were available.

Regards,

Sylvain

[rprosperi]

Thanks Jan, for sharing all these details. And great news that you will order a PIL-Box, it will unlock and ease exploration of your 71B and all the wonderful software around the community for it.

I'm a bit confused about your configuration though. In the SHOW PORT output, it shows a 16KB ROM (or EPROM) which you list as being a 64K RAM module, and also 32K RAM in ports 4.00 and 4.01, which would have to be the 64KB RAM module. I assume these two modules were swapped between you initial SHOW PORT and later description, is that the case?

The EPROM in Port-2 looks uninteresting (all files are BASIC) however the names have no meaning for me as I don't read German. Can someone suggest Anglicized versions of the filenames?

OTOH, the module in Port-3 looks quite interesting with several new looking LEX files.

I suspect the modules are used as a pair, with the P2 module containing all the application specific code, and P3 containing utility keywords and BASIC (sub?) programs (INDEX2, PRINT), and it will be interesting to explore these once available.

While waiting for your PIL-Box, suggest you read up on the ROMCOPY LEX file, and also start to explore Joe Horn's Online LIF Disk Project, a collection of most of the community LEX and utility files for the 71B, 75C and a little 41C stuff.

[Garth Wilson]

Maybe someone here knows otherwise; but I think the batteries in the RAM modules are only there to hold the memory if you remove the modules from the computer such they they would not be able to use the computer's power. As long as you leave the module in the port and the computer can keep its onboard RAM and clock alive, the modules should be fine without their own battery. I have a CMT 96K card-reader-port RAM and 64K front-port RAM in mine.

[Jurgen Keller]

I think the W&W VRB module is this one:
W&W VRB Funktionsmodul für den HP 71

It contains a bunch of functions, as listed on the next page. Some exotic ones like "KOJAK: A howling BEEP command" are also included. Would love to hear that sound! ;-)

[Sylvain Cote]

(08-23-2022 07:09 PM)Garth Wilson Wrote:  Maybe someone here knows otherwise; but I think the batteries in the RAM modules are only there to hold the memory if you remove the modules from the computer such they they would not be able to use the computer's power. As long as you leave the module in the port and the computer can keep its onboard RAM and clock alive, the modules should be fine without their own battery. I have a CMT 96K card-reader-port RAM and 64K front-port RAM in mine.

Yep! the batteries of my front-port/card-reader CMT/HHP RAM modules are dead and all of them are perfectly working, they just loose their content when removed from the 71B.

[J-F Garnier]

A really great HP-71B system sample!
The only obvious missing item is the MATH ROM, and at your option the JPCROM too.
With all the available memory, you will have no problem to load them.

(08-23-2022 05:46 PM)rprosperi Wrote:  I'm a bit confused about your configuration though. In the SHOW PORT output, it shows a 16KB ROM (or EPROM) which you list as being a 64K RAM module, and also 32K RAM in ports 4.00 and 4.01, which would have to be the 64KB RAM module. I assume these two modules were swapped between you initial SHOW PORT and later description, is that the case?

The 16KB ROM is probably the FORTH/Assembler ROM.
Here is my understanding on the SHOW PORT Output:
0.05 16384 2 : HP-IL
1 16384 2 : FORTH
2 65536 2 : 64K EPROM
3 32768 2 : 32K EPROM
0 4096 0, 0.01 4096 0, 0.02 4096 0, 0.03 4096 0 : internal 16K RAM (4x4KB)
4 32768 0, 4.01 32768 0 : 64K RAM (always set as 2x32K)
5 32768 0, 5.01 32768 0, 5.02 32768 0, 5.03 32768 0 : 128K RAM (4x32k)

Quote:OTOH, the module in Port-3 looks quite interesting with several new looking LEX files.

I suspect that the WUWROM1L and KABULEX LEXs are compilations of existing LEXs, plus maybe specific support LEXs.
The VER$ response:
HP71:2CDCC HPIL:1B FTH:1A EDT:A KBD:B W&W:A CSTU:A CSTU:A EDT:A DATA:B
shows a specific W&W LEX, plus 2 times the CSTU (I guess the well-known CUSTRGLX LEXs) and the DATA:B seems familiar to me too.
Note that EDT:A is duplicated too, meaning the EDLEX, already present in the FORTH ROM, is duplicated in one of the LEXs of the 32K EPROM, together with the EDTEXT and EDKEYS files.

Jan, you may want to reprogram (after properly saving their contents) the EPROM modules with more interesting material for you, all you need is to find someone near you, owning the programming tools, to do it for you :-)

J-F

[rprosperi]

I agree with your comments J-F, the modules were simply swapped later.

I hope the LEX files W&W:A and DATA:B have some new goodies. I've seen the W&W:A in an eBay listing last year I couldn't buy, but don't recall the DATA:B LEX.

Should be interesting to explore.

[J-F Garnier]

(08-23-2022 10:49 PM)rprosperi Wrote:  I hope the LEX files W&W:A and DATA:B have some new goodies. I've seen the W&W:A in an eBay listing last year I couldn't buy, but don't recall the DATA:B LEX.

Should be interesting to explore.

DATA:B is the VER$ signature of DATALEX found for instance on lexfl1.lif volume.
It provides keywords to manage data files: DRECORDS, DINSERT, DDELETE, ...
But it may be something different here.

Interesting indeed!

J-F

[JanS]

All,
I'd like to give some feedback to replies to my initial post which started this thread as well as a first progress update on where I am with regard to preserving the two W&W Eproms for posterity.

(08-23-2022 01:47 PM)Maximilian Hohmann Wrote:  ...This must be about as much memory as one can fit into an HP-71B!

My first association with "W&W" and "VRB" is "Wüstenrot & Württembergische" and "Volks- und Raiffeisenbanken". The first two are a building society and an insurance company in Stuttgart, Germany, the latter a group of banking cooperatives in Germany.

Yup - it is more or less maxed out. "W&W" is definitely referring to W&W Datentechnik and "VRB" might be any Volks- and RaiffeisenBank - I wrote to Wilfried Kötz, he deems it entirely possible that W&W burned those Eproms some 30 years ago, however he has no recollection of this specific set (I supplied the CAT outputs together with my inquiry)

A card reader would be "nice to have" along with some cards, but it is not something that's high on my TBA list.

(08-23-2022 03:40 PM)KimH Wrote:  Oh my - you have clearly made a good buy here - this is the king of configs! Congratulations!!

I have replaced the battery in all my CMT Card Reader "ports" - not a big challenge if you know how to handle a soldering iron (and watch polarity - obviously) - they can be bought in all sorts of sizes - mine are smaller than what was in there, with wires welded on them AND has the "Heat Shrunk" cover. about 3€ a piece "Dell BackUp Battery" is printed on them

The flat battery for the 64k I also have - it still has a voltage (I took it out and stored it) - I think the right expression is "Unobtainium".. have not found anything to replace it.

Kim, thank you for the tip about the Dell Backup Battery Type - much appreciated and now on order for my replacement project.

The flat "Unobtainium" one in my 64k module has about 2,2 to 2,0 Volts left - I pulled it and it's now in Storage in a little plastig bag to protect from accidental shorting.

(08-23-2022 05:46 PM)rprosperi Wrote:  ... I'm a bit confused about your configuration though. In the SHOW PORT output, it shows a 16KB ROM (or EPROM) which you list as being a 64K RAM module, and also 32K RAM in ports 4.00 and 4.01, which would have to be the 64KB RAM module. I assume these two modules were swapped between you initial SHOW PORT and later description, is that the case?

The EPROM in Port-2 looks uninteresting (all files are BASIC) however the names have no meaning for me as I don't read German. Can someone suggest Anglicized versions of the filenames?

OTOH, the module in Port-3 looks quite interesting with several new looking LEX files.

I suspect the modules are used as a pair, with the P2 module containing all the application specific code, and P3 containing utility keywords and BASIC (sub?) programs (INDEX2, PRINT), and it will be interesting to explore these once available.

While waiting for your PIL-Box, suggest you read up on the ROMCOPY LEX file, and also start to explore Joe Horn's Online LIF Disk Project, a collection of most of the community LEX and utility files for the 71B, 75C and a little 41C stuff.

Hi Bob,
your's and J-F's suspicions/assumptions are of course correct - I mixed up the order of the modules while documenting / photographing and did not proof read my initial post thoroughly enough. Thanks for mentioning Joe's project - I had already stumbled over that link and I will definitely explore that resource a lot more. As I'm still new to the 71, I am reading the user manual at the moment to get a hang of general operation. Once I feel a little more secure operating the machine and have all the tools in place, I will probably come back here for guidance on romdumping.

With regard to anglizied module names, there isn't really much, other than everything xxxDRUCK probably refers to printing and SICHERN means to backup, so there is that.

(08-23-2022 07:09 PM)Garth Wilson Wrote:  Maybe someone here knows otherwise; but I think the batteries in the RAM modules are only there to hold the memory if you remove the modules from the computer such they they would not be able to use the computer's power. As long as you leave the module in the port and the computer can keep its onboard RAM and clock alive, the modules should be fine without their own battery. I have a CMT 96K card-reader-port RAM and 64K front-port RAM in mine.

Hi Garth,
that works fine as long as you have a means of powering the 71 once the 4 AAAs need replacing. I don't have an external power supply for the machine, so thats on the TBA list for sure.

(08-23-2022 07:16 PM)Jurgen Keller Wrote:  I think the W&W VRB module is this one:
W&W VRB Funktionsmodul für den HP 71

It contains a bunch of functions, as listed on the next page. Some exotic ones like "KOJAK: A howling BEEP command" are also included. Would love to hear that sound! ;-)

Hi Juergen, sorry - apparently no such luck and so, no KOJAK MP3 to post here. This must be a different EPROM set AFAIK.

So, for now, here's what will happen next on my end:
The PIL Box Kit will show up at my door in the near future as I'm assured by J-F.
I'll get to soldering the kit and then I'll DIY an HP-IL Cableset - there's a great ressource here: How to Make Your Own HP-IL Cables to get the connection going (unless somebody want's to part with a surplus cable)
I'll read up on the rom dumping procedure as suggested by Bob.
Once ready, I'll dump the roms and make them available for preservation and posterity.
I'm in this for the learning expirience and I really appreciate the generous private offer from one of the forum members to exchange my roms for same type versions programmed to my liking, however, I'd rather use the opportunity to learn the ins and outs of this machine along the way - so it may take a little longer until the roms become available, but it's not like that they have been hot off of the flasher. They live inside the machine, UV erase windows covered and will probably do so without a problem until they have been dumped. At that point, I'll likely have to make a decision on what to do with them, but that is still some time away in the future

So, in the meantime, stay healthy and keep calculating,
Jan

[Garth Wilson]

(09-05-2022 02:45 PM)JanS Wrote:  

(08-23-2022 07:09 PM)Garth Wilson Wrote:  Maybe someone here knows otherwise; but I think the batteries in the RAM modules are only there to hold the memory if you remove the modules from the computer such they they would not be able to use the computer's power. As long as you leave the module in the port and the computer can keep its onboard RAM and clock alive, the modules should be fine without their own battery. I have a CMT 96K card-reader-port RAM and 64K front-port RAM in mine.

Hi Garth,
that works fine as long as you have a means of powering the 71 once the 4 AAAs need replacing. I don't have an external power supply for the machine, so thats on the TBA list for sure.

I suspect that the same capacitor that keeps the mainframe alive when you change the batteries would also keep the modules' RAM alive. I'm quite sure I removed the card-reader-port CMT RAM's internal battery long before my last 71 AAA battery change, and changing the batteries did not make the CMT RAM lose any memory.