71B vs 75D

[dhe]

I found an ATT 75D pretty cheap on ebay, and thought it might be a nice companion to my new to me 71B.

Anyone have any thoughts of 71B vs 75B? I think the 71B is the better looking and better sized unit.

[rprosperi]

(04-13-2021 03:47 AM)dhe Wrote:  I found an ATT 75D pretty cheap on ebay, and thought it might be a nice companion to my new to me 71B.

Anyone have any thoughts of 71B vs 75B? I think the 71B is the better looking and better sized unit.

As a long-time 71B user, I acquired some 75C units in ~2015 to explore and get educated on them. I had always believed the 71B was simply better in all ways, but this turns out to not be true, the 75C is faster (for math) easier to type on, has some capabilities beyond the 71B and some other unique features too.

I did a presentation on the 75C at an HHC meeting in 2017, summarizing many of my findings; a video is available on YT here: https://www.youtube.com/watch?v=Ndwek0QKqrU

TL;DR - The short version is I recommend you to get it, it's really a very interesting machine, with its own charm and unique personality, and they can usually be acquired for less than a 71B (plus they have HP-IL built-in so no need to purchase that too).

If you like using emulators, you can also check out Jean Francois Garnier's EMU75 here: http://www.jeffcalc.hp41.eu/emu75/. The user experience on an emulator is clearly quite different from a real device, but EMU75 provides an extremely accurate reproduction of the 75C's behavior and capabilities.

If you do get it, come back and share your experiences...

[Maximilian Hohmann]

Hello!

It is definitely worth having one of those in the collection. As a pure calculator it is not very useful and using the (manual feed) card reader needs a lot of patience.
If you can find one, get also the leather pouch for it. That must be the most robust calculator case ever made, it is like the ones that came with expensive cameras long before the age of digital.

Regards
Max

[Gene]

Bob's presentation is a good one!

Here are two PPC Computer Journal Articles that compared the HP-75 to the HP-71. FWIW.

Gene

[Dave Britten]

I think we need to address the real grudge match: HP 75D vs. Tandy Model 100/102.

(Hopefully nobody talks me into going out and buying a 75D...)

[rprosperi]

(04-13-2021 04:51 PM)Dave Britten Wrote:  I think we need to address the real grudge match: HP 75D vs. Tandy Model 100/102.

(Hopefully nobody talks me into going out and buying a 75D...)

C'mon Dave, you know it's inevitable.

The 75D that's currently listed (with a laptop thrown-in !?!?) is nice because it includes a POD, which are fairly rare these days, but I'd make sure the seller tests it, or accepts returns. It looks nice, but who really knows...

The POD provides:

-Built-in 300 baud modem (yawn... but, you can hook up 2 x 75/POD machines and have them call and connect to each other using the modems.)
-RAM-Disk (almost certainly 64K - there was a 32K option, but I've never seen one)
-Barcode scanning s/w (for the 75D barcode port) (yawn again...)
-Holds 2 normal classic battery packs
-Can be used with 75C as well as 75D machines

The most interesting thing is the RAM-Disk can actually contain folders and sub-folders. One of the most interesting HP accessories IMHO.

If I won that, I'd have the seller toss out the laptop to dramatically cut the shipping costs.

[Sylvain Cote]

(04-13-2021 05:29 PM)rprosperi Wrote:  The POD provides:
...
-Built-in 300 baud modem (yawn... but, you can hook up 2 x 75/POD machines and have them call and connect to each other using the modems.)

Some do not have the modem in it. (I have one like that)

(04-13-2021 05:29 PM)rprosperi Wrote:  -RAM-Disk (almost certainly 64K - there was a 32K option, but I've never seen one)

RAM-Disk sizes was 64KB, 32KB and 24KB. (I have 64KB and 32KB versions but not the 24KB version)

(04-13-2021 05:29 PM)rprosperi Wrote:  -Holds 2 normal classic battery packs

Absolutely need the two battery packs to work, the modem consume a lot of power.

[dhe]

Thanks Bob, that was an excellent tech talk you gave!

[rprosperi]

(04-13-2021 08:26 PM)dhe Wrote:  Thanks Bob, that was an excellent tech talk you gave!

You're quite welcome, but I guess the proof is in the pudding, as they say...

Was it enough to sway you to get one ?

[Andres]

IIRC, the 75C has a Capricorn processor (derived from the desktop HP 85), but the 71B has a Saturn processor. IF you are interested in microprocessor architecture or assembly language programming AND IF there are assembler tools available (I'm not sure), that might be an interesting aspect about the 75C.

[Sylvain Cote]

(04-13-2021 03:47 AM)dhe Wrote:  Anyone have any thoughts of 71B vs 75B?

The HP-75C/D is a scale down version of the HP-85 desktop computer (CMOS version of the same 8 bits CPU) and uses a BASIC language dialect that is similar to the 80 series.
This portable computer shines when used with the VisiCalc module, a 80 columns video interface, a 80 column printer and a floppy drive.
It has three modes of operation: clock, appointment and BASIC. It is also a lot faster than the HP-71B.

The HP-71B is a landscape scale up version of the HP-41 using BASIC instead of FOCAL. (It's initial planned name was HP-44!)
This handheld computer is bigger than the HP-41 but smaller than the HP-75C/D, it has a more powerful BASIC implementation, a better HP-IL implementation, can have a lot more RAM and has more softwares for it.
It has two modes of operation: Calc and BASIC.

[Dave Frederickson]

(04-13-2021 11:52 PM)Andres Wrote:  IIRC, the 75C has a Capricorn processor (derived from the desktop HP 85), but the 71B has a Saturn processor. IF you are interested in microprocessor architecture or assembly language programming AND IF there are assembler tools available (I'm not sure), that might be an interesting aspect about the 75C.

Not only are there assembler tools available at https://groups.io/g/hp75 and https://groups.io/g/hpseries80, but Joachim Siebold, creator of pyILPER, has a Capricorn Assembler.
https://github.com/bug400/capasm

[Garth Wilson]

(04-14-2021 12:15 AM)Sylvain Cote Wrote:  [The 75] is also a lot faster than the HP-71B.

Gene's second attached file above, the V3N2P29-32 one, says on the right column of p.30 (p.2 of the .pdf):

...Using the same [aforementioned] benchmarks, the 71 appears to be running at only one-third of the speed of the 75, and programs which, on the latter, appear to be instantaneous cause noticeable delays on the 71 (which give problems because the buffer may allow INPUT pre-keying but does not allow the same ease of use with KEY$). However, those benchmarks are heavily weighted towards the simplest of arithmetic coupled with many jumps and subroutine calls. A program which replaces the trivial arithmetic of the benchmarks with something worthy of a computer, albeit running a small loop, gives an astonishing result: the 71 runs at the same speed as the 75. This is because the processor of that machine, like the 41, is designed for ease of processing numbers in the decimal, floating-point format used by the computer and is even less of a general-purpose computer than the 75/80-series CPU.

[Dave Frederickson]

As an HP-IL controller the 71 is both faster and more capable than the 75. When paired with the Data Acquisition ROM and a 3421A Data Acquistion/Control Unit the 71 becomes a quite capable data acquisition system.

[Sylvain Cote]

(04-14-2021 02:19 AM)Dave Frederickson Wrote:  As an HP-IL controller the 71 is both faster and more capable than the 75. When paired with the Data Acquisition ROM and a 3421A Data Acquistion/Control Unit the 71 becomes a quite capable data acquisition system.

I agree up to a point.

The HP-75 paired with the I/O ROM reduce the differences to maybe three major things in favor of the HP-71B, the Dual HP-IL option, the non-controller capability and the raw speed of the 71B IL module.
Apart from these, both can expertly control any HP-IL devices.

For sure the HP-71B Data Acquisition ROM allow you to use the unit without knowing its inner working, but still.
The 3421A data acquisition unit only has 14 commands string and with an intermediate HP-IL/HP-IB knowledge, it is fairly easy to control the unit without the ROM.
From my experience, an HP-71B with an HP-IL module or an HP-75C/D with an I/O ROM module can both easily control any HP-IL devices, including the 3421A.

[Andres]

Dave, Thank you for the links to Capricorn tools!

(04-14-2021 12:23 AM)Dave Frederickson Wrote:  

(04-13-2021 11:52 PM)Andres Wrote:  IIRC, the 75C has a Capricorn processor (derived from the desktop HP 85), but the 71B has a Saturn processor. IF you are interested in microprocessor architecture or assembly language programming AND IF there are assembler tools available (I'm not sure), that might be an interesting aspect about the 75C.

Not only are there assembler tools available at https://groups.io/g/hp75 and https://groups.io/g/hpseries80, but Joachim Siebold, creator of pyILPER, has a Capricorn Assembler.
https://github.com/bug400/capasm

[hth]

This was interesting. I had a look at the Capricorn CPU and it seems like a quite capable and interesting 8-bit ISA.

Is it possible to write assembly language programs for the HP-75 and just bypass the built in BASIC? What about documentation, if I want to access HP-IL at assembly level, is it around, both hardware and system listings?

[rprosperi]

(04-14-2021 04:50 PM)hth Wrote:  This was interesting. I had a look at the Capricorn CPU and it seems like a quite capable and interesting 8-bit ISA.

Is it possible to write assembly language programs for the HP-75 and just bypass the built in BASIC? What about documentation, if I want to access HP-IL at assembly level, is it around, both hardware and system listings?

You can write LEX files in assembler, but I believe there is not any way to create a complete binary program file, the 75C has no native support for this type (which is why the 71B, which came a year later, added this capability). So you can write a shell program in BASIC, but use new KEYWORDS from LEX files to do the heavy lifting.

There is no IDS for the 75C, however the 75C OS listings were released under NOMAS, and are included in the MoHPC document set, which you likely have.

Also, the I/O ROM listings are there as well, and this is loaded with HP-IL stuff. In fact the native 75C can only handle simple user level commands (COPY file, PRINT, CAT, etc.) on its own, the I/O ROM is needed to do anything meaningful. There is also a small LEX file RIOWIO (Read I/O, Write I/O) available, which I believe is also floating around somewhere in source form. The I/O ROM may provide everything you need, it greatly extends the 75's HP-IL capabilities.

If you're interested in getting into the 75C/75D, I suggest you join this news group, and look at the quite extensive set of documentation:

https://groups.io/g/hp75

[hth]

(04-14-2021 05:18 PM)rprosperi Wrote:  If you're interested in getting into the 75C/75D, I suggest you join this news group, and look at the quite extensive set of documentation:

https://groups.io/g/hp75

Thanks, I joined. Impressive stuff. Now I have to ponder if I should get a HP-75...

[rprosperi]

(04-14-2021 08:32 PM)hth Wrote:  

(04-14-2021 05:18 PM)rprosperi Wrote:  If you're interested in getting into the 75C/75D, I suggest you join this news group, and look at the quite extensive set of documentation:

https://groups.io/g/hp75

Thanks, I joined. Impressive stuff. Now I have to ponder if I should get a HP-75...

You can explore the 75 using Jean-Francois Garnier's DOS-based Emu75, found here:

http://www.jeffcalc.hp41.eu/emu75/index.html

Although "DOS-based" sounds troublesome, it's easy to setup and runs fine in DOSBox, and it also works fine with Virtual HP-IL with ILPer and pyILPer.

It's a very high accuracy emulation, about 99.9% of 75 operations work the same, so it's easy to get a quick 'feel' for using the 75C, only costing a little bit of time.