Seven HP-71B Calculators and Four ThinkJet Printers

[mfleming]

Those of you who follow TAS for listings on 71Bs may remember this listing from about a month ago. It was over in a few hours. Strangely, clicking on the old link results in a We Looked Everywhere message and clicking on the Leave Feedback button says feedback is no longer available. The listing doesn't show up in the Sold listings. The seller mentioned some difficulties he was having with TAS regarding the feedback. If the seller Ed is a member here, I'd be interested to know how things turned out (PM me). I didn't want to continue to communicate through TAS if it could have made things worse



Three of the four printers have an HP-IL interface while the fourth has a DB25 RS232 Serial interface. Their condition is fine and ink cartridges are present. I haven't checked to see if any of the batteries can hold a charge, but opening one up showed a touch of green residue. Might be best to do a rebuild, and that would be just the excuse I need for finally getting a small spot welder.

Of the seven HP-71Bs, the three Survey models with overlays were well equipped. Of the four spares with cases, two required a touchup to remove a little residue. They work fine, but a third of the four has more extensive battery leakage damage. The chrome is stripped from some of the contacts and the back shell shows discoloration. It needs to be opened to see if it can be repaired. If the flex is the only damage, then it would be easy to make a new one. Custom flex cost has dropped considerably since I last made some (see avatar).

Here's a summary of the seven calculators.

Code:


Ser#:  2427A00230, 2512A00514, 2549A00039, 2603A00175
       2722A00054, 2723A00065, 2815A00141
HP71:  1BBBB (3), 2CCCC (2), 2CDCC (1)
HPIL:  1A (4), 1B (2)
CR:    HAND HELD PRODUCTS 71M/M 96K RAM (1),
       CMT MEMORY MODULE CR-128R (1 4-chip, 1 contiguous)
FP:    5061-7238 HP-71 SURVEYING (3),
       CMT71-64E CASSERA SURVEYS INC (3),
       32K RAM (4), 4K RAM (3), HP-71 AC Circuit (1)

The CMT modules are curious. One shows up as four chips in a SHOW PORT listing but the other, marked Contiguous, shows up as a single 128KB chip. I thought I had seen previous postings that said a 32KB chip is the largest that can be enumerated. No mention is made of the difference in Sylvain's Compendium.

I'll post these in the Classified forum over the coming months. Thinking maybe a beginners starter set with HPIL, MultiMod, and 4KB RAM? We'll see!

~Mark

   

[rprosperi]

This listing was quite strange, after this listing disappeared (I assume pulled down) I too could not find any trace of it, as if it was never listed. I wonder how that is arranged....???? Hmmmm....

As for the CR RAM modules, the 64K module is ootb, configured as 2 x 32 KB modules, but by cutting and jumpering some traces on the board, can be readily converted to a single 64KB module, which is important as this is essential to house the image which will burned to a 64KB EPROM module.

I'll guess that CMT built the board for the 128KB module using the same technique, of cutting/jumpering traces to daisy-chain the 4 x 32 chips into a monolithic 128KB RAM chip. I have 2 of these 128K modules which act as 4 x 32, and a third which I have not installed yet, so not positive about how they ship, however just open the module case and examine the leads, you'll probably find cut traces, etc.

It's a long thread, but there's info in here about this topic - can't find links at the moment, but both J-F and Paul Berger have created and shared docs on this topic, if not shared by someone else (Dave F) shortly, I can send you the docs.

https://www.hpmuseum.org/forum/thread-10300.html

[J-F Garnier]

I didn't notice this listing. Great package !

Now, for the techncal aspects:

(10-25-2024 06:38 PM)mfleming Wrote:  The CMT modules are curious. One shows up as four chips in a SHOW PORT listing but the other, marked Contiguous, shows up as a single 128KB chip. I thought I had seen previous postings that said a 32KB chip is the largest that can be enumerated.

Indeed, the HP-71 Hardware IDS specifies that the max size of a RAM chip is 64Knib = 32KB.
However, the limitation is about chip size. There is a mechanism to chain up to 16 chips to build a port. So a 128KB port is possible.

We know how to modify a HHP card reader RAM module to chain the 32KB chips. I documented it here.
We also know the CMT-71-P01 EPROM programmer that has 64KB of RAM that can be configured (with a switch) either as two 32KB ports, or a single 64KB port.

But I wasn't aware of a CMT CR RAM module that can be configured differently from individual 32KB ports.
Any details would be interesting ! I have a 128KB CMT CR RAM module and would love to know how to modify it.

J-F

[mfleming]

(10-25-2024 08:34 PM)J-F Garnier Wrote:  But I wasn't aware of a CMT CR RAM module that can be configured differently from individual 32KB ports.
Any details would be interesting ! I have a 128KB CMT CR RAM module and would love to know how to modify it.

J-F

From what you and Bob say, I should open the module and document its configuration. Unlike the four-part CMT module, this one lacks a serial number information sticker and just has the label "Contiguous." Maybe a mod by the owner or knowledgeable friend? Time to find out...

~Mark

[Dave Frederickson]

The pin on the RAM controller you're looking for is affectionately called LCIM as it functions like the LCIM bit when configuring FRAM71.
Docs are here:
http://www.jeffcalc.hp41.eu/files/hhp96k.pdf
http://www.jeffcalc.hp41.eu/misc/files/hhp.pdf

The LCIM pin is referenced in Note 8 in hhp.pdf.
The state of this pin determines weather the module reports as the last
chip in the module or not. When it is tied high it reports as the last chip
in module but when it is low it does not and its capacity will get added
on to the next memory device in his way logical memory blocks larger
than 32K can be created.

The CMT modules use a different memory controller, but it functions the same.

The pdfs show the modification for the 1LJ4 interface chip.

[rprosperi]

I stand corrected (I'm traveling and cannot check the actual items) but indeed the 96K CR module I have is an HHP module, in which Paul made mods according to these docs so it now has 1 x 64KB and 1 x 32KB RAM logical modules inside.

[Garth Wilson]

(10-26-2024 01:59 AM)rprosperi Wrote:  I stand corrected (I'm traveling and cannot check the actual items) but indeed the 96K CR module I have is an HHP module, in which Paul made mods according to these docs so it now has 1 x 64KB and 1 x 32KB RAM logical modules inside.

Here are pictures of the inside of my CMT 96KB CR RAM module.  Up to 160KB was available at the time, but RAM was still very expensive, and I set a budget and 96KB was all that fit in that budget.  (At another time though, I did also get a 64KB front-port RAM module, so I got and extra 160KB anyway.)

[J-F Garnier]

(10-26-2024 01:59 AM)rprosperi Wrote:  ... the 96K CR module I have is an HHP module, in which Paul made mods according to these docs so it now has 1 x 64KB and 1 x 32KB RAM logical modules inside.

Indeed, a 96KB or 128KB module should be configured with at least one 32KB port (and not as a single 96KB or 128KB port), to be safely used with a HP-71 1BBBB :

Quote:For the HP-71B with VER$=1BBBB, there is a bug [..]. It shows up only if there are IRAM(s) in the HP-71B
which have a chip size of 32K bytes, the first IRAM containing 32K byte chips has two or more chips, and the
system does NOT include a FORTH/Assembler Module. Both the 64K and 96K RAM modules from Hand Held
Products have a chip size of 32K bytes. [...] The 96K RAM module is usable without the FORTH/Assembler
module if the PORT(5) is 32K bytes and PORT(5.01) is 64K bytes.

From the Soft Forth manual (p.2.2)

J-F

[Dave Frederickson]

(10-26-2024 07:17 AM)J-F Garnier Wrote:  From the Soft Forth manual (p.2.2)

... and from the 71B EPROM programmer manual, p. 12.

CAUTION: When in the 64K mode, always have a FORTH ROM inserted
into another HP-71 port. This prevents a bug in the HP-71 operating
system from configuring the 64K RAM block incorrectly. The
FORTH ROM must be inserted to FREEPORT the RAM correctly.

The bug was fixed with the 2CDCC firmware.

[mfleming]

Interestingly, the model with the CMT 128KB marked "contiguous" is version 2CDCC. It appears as a single 128KB memory.

The model with the HHC 96KB is version 1BBBB, shows MEM() as 115125, but nothing in port 5 appears with a SHOW PORT listing.

In a version 2CDCC model, the same HHC shows as three 32KB memories, 5, 5.01, and 5.02.

Hummm...

[Dave Frederickson]

(10-26-2024 07:58 PM)mfleming Wrote:  The model with the HHC 96KB is version 1BBBB, shows MEM() as 115125, but nothing in port 5 appears with a SHOW PORT listing.

That's because the 1BBBB SHOWPORT doesn't show MAIN RAM. There is a SHOWPORT LEX file that will show MAIN RAM.