HP-41CV Card reader essential?

[CheshireChris]

Hello everyone, this is my first post here. I ask forgiveness in advance if some of the questions I'm probably going to ask are really elementary.

I'm a retired physicist and computer programmer, and have very distant memories from the 1980s of using programmable calculators. I thought it would be interesting to explore the devices of this era, so I've just bought a bundle of used HP gear including an HP-41CV calculator. I don't have it yet - it should arrive in a few days.

The calculator has an "Extended functions" module and two "X-Memory" modules installed in three of its four expansion slots. The bundle includes a fair number of magnetic cards, but no card reader - the chap I bought it from sold that separately at an earlier time, unfortunately.

Am I right in thinking that each of the two "X-Memory" modules acts as an external storage device and can be used for storing programs, rather like a computer's hard disk drive? Should the two modules give me enough space to be able to do a reasonable amount of programming experiments?

How essential is it to have a card reader? They seem to command quite high prices, and I've been reading about issues with "gummy wheels". Will I be able to use my HP-41CV with X-Memory modules sensibly without a card reader? Are there any other essential accessories I should consider?

All advice would be very welcome!

Thanks,

Chris

[emefff]

Hello!

This configuration is already the maximum possible regarding memory (at least, back in the old days :-) ). Actually, 'X-functions' + 2* 'X-memory' was the setup flown in the space shuttle in the early 80s. There's not much more you can do with original modules.

'X-memory' is a drive rather than calculator memory, this is correct. You'll have to move your programs into the calculator memory to use them. Is this is enough for you, only you can know.

The card reader is only 'essential' if you exceed this memory limit, which is quite large. 600 registers in total in the modules amounts to around 600*6=3600 program steps. I do not know if you need that, that's for you to decide. There are modern ways around the card reader, though.
For me, the reader is not essential. I have one (it is even repaired and usable), but I never use it. Its big disadvantage is a VERY high battery consumption. That does not go well with the two X-memory modules, because their memory is volatile. If your batts are weak, you can literally see them dying with the card reader motors.

Other essentials? Also for you to decide. For me, ADVANTAGE (integration) and MATH (hyperbolics) are essential, as is the NoV-64D (non-volatile flash and all original ROMs uploadable, programs transferable to other 41s and HUGE space for own programs, around 1700 regs if I remember correctly). NoV-64D takes the 41 to another level, it may make the card reader completely obsolete.

I would just start using the 41, write some programs, see if you like your workflow and decide later. There are a lot of readers around and some people even offer repair service. Other ROMs and special modules also seem to live forever, they are not going away soon,

have fun,

Mario.

[RPNerd]

Hi Chris,

Going by your username I would guess that you're not too far from me (Lancs).

A card reader is definitely not necessary but it does help safeguard programs that you've written and data that you've accumulated from loss of power. You are correct in thinking of X-Mem as a kind of external storage facility in that the 41 can save stuff to it and retrieve stuff from it later but cannot work directly with it.

Take a good look at the manuals for the CV and the X-Func and X-Mem modules. You can find them here: https://literature.hpcalc.org/#model:41CV

The contents of your X-Mem is preserved as long as there's power in the batteries. If you remove the batteries, it's lost.

Quick tip to help mitigate this: find yourself a second battery holder (thecalculatorstore.com sells them 3D-printed). When the time comes to replace the batteries, fill the spare battery holder with a set first, then simply swap old for new. The operation takes no more than 3-4 seconds and the memory contents should survive loss of power that long.

[ThomasF]

HI Chris,

As already mentioned, the card reader is good for backup.

But a better modern solution would be to get a HP-IL interface and a PIL-box (just search this forum for a coming device).
With this you can backup to a PC instead (as a masstorage device), apart from everything else (like printer support etc).

Or, wait for the TULIP4041 device, which will support HP-IL without the need for the hw interface - and a lot more. Note that this is still in development phase, and not ready for preproduction yet.

Any way, good luck with your new calculator and welcome to this forum!

Happy programming!

Cheers,
Thomas

[Garth Wilson]

I'm writing kind of a lot since you're new to the 41.

When I replace the batteries in my 41cx, I don't have a spare battery holder to make the swap quickly.  Just replacing the batteries one by one in the holder and then putting it back in, I have never lost memory, either main or EXTended memory.  I seem to remember having had the batteries out for a few hours one time in the 1980's, and the internal capacitor kept the memory alive.  A few of the programs I use most have been in the calc continuously for probably 30 years, never needing to be re-loaded.  I don't remember exactly how long; but I think the last time I lost memory was probably when I was new to synthetic programming in the late 1980's and did something that corrupted the chain in main memory.

Registers are 7 bytes each, not 6, so rather than 600*6=3600 program steps, it's 600*7=4200 bytes.  (A program stem can have more than one byte though; in fact, a text string can be a lot more.)

I never went for the card reader.  Since my original purpose in getting the 41 was to control, and take data from, equipment on the workbench (which I don't use it for much anymore), I needed the HP-IL module anyway, so I got the high-speed microcassette drive which acts like an intelligent disc drive with a file-allocation table and one cassette can have loads of files, each potentially holding many, many cards' worth of data, and not requiring feeding the cards through by hand at the right time or order.  I also wanted the Extended I/O (XIO) module, and I got the HP-IL and XIO integrated, from EduCALC, so together they only take one port.  I've had a lot of things connected simultaneously via HP-IL.  I have two tape drives, and in spite of their age of nearly 40 years, they still work fine, never having had any repairs.  (I have to connect an external power supply to the battery terminals though, as my battery packs died long ago.)  Tape machines generally have rubber wheels and belts that rot and need replacement; but not these.  They use direct drive, and no capstan.  It seems like the main problem is with the pressure pad in individual cassettes rotting so it doesn't press the tape up against the head anymore.  I think I did fix a cassette or two for this reason.

I have two HP-71B's too, which I've used the tape drives for more, and I can't remember the last time I used a tape drive for the 41cx.  (The cx has the Extended Functions / Extended Memory module built in, plus the time module, text editor, and a few things you can't get in a cv, and then I also have a double Extended Memory (XMem) module, so the two only take up one port.)  I keep lots of programs in main memory, and I mainly use the XMem for text files and data files, although I move programs into it also when I seem to be done with them but I'm not totally sure.  The amount of memory there is quite a bit considering how the 41 gets used.  I just checked, and I have 14 files there now and it's 71% full.  After I see I've gone a long time without using an old program file and I can be pretty sure I'll never need it again, I purge it.  All that is to say I doubt you'll need a card reader.

If you get pretty serious about using the 41, you'll want to get one of the modern modules that hold lots of module images in flash memory.  A couple of the newest modules that come to mind that we're looking forward to here on the forum is the 41 MAXX and the TULIP4041.  There's far more capability there than I will take the room to list here.  Angel and others have introduced lots of excellent ROM module images in the last decade or less which are mostly written in assembly language and perform far better than most of HP's modules; for example, his 41z module gives the 41 a real 4-level complex-number stack and has over a hundred complex-number functions.  I've used the Advantage module a lot partly for its complex-number functions; but of the ones it has (which are few compared to Angel's 41z), the 41z seems to generally be about ten times as fast.  My own CATalog 2 (the catalog of installed modules) shows the following on the HP92198 HP-IL 80-column video interface and monochrome monitor.  Many of these listed are in Diego's CLONIX-D hardware module:
   
The WarpCore you see there is another one of Angel's which has 140 general-purpose functions that improve the speed and compactness of programs in any discipline.  The ZENROM module makes synthetic instructions as if they're not synthetic, and has other functions like a direct RAM editor.

There's more capability in the 41 world than anyone could have imagined four decades ago, thanks to engineers and programmers continuing, to this day, to make new module hardware and software.  I'm a fairly serious user; but there are others on this forum who know a thousand times as much about the innards as I do.

[John Garza (3665)]

All good information in the responses.

But getting down to the point...

Any computing device needs an easy way to get programs/data into/out of memory.
With hundreds/thousands of steps, keyboard use is out of the question for frequent programming work.
(foundational point #1)

Back in the day, the technology used was a card reader. Already developed for the HP-65.
(foundational point #2)

Modern technology has somewhat surpassed that, assuming the available memory is sufficient to hold all the software or data you will ever need. This makes some assumptions about the future, and is not guaranteed.
(critical point #1)
However, this is almost always adequate for casual users.

Heavy programming with hundreds of user developed programs may conflict with that - even the primitive file management tools (catalog, xeq alpha, etc.) of the 41C were not built to handle that.
(critical point #2)

So, in my opinion, it's essential to have one if you are 'collecting' the 41C line.
But not essential for general daily use.

Something else to consider is that the real reason manufacturers moved away from card readers was not replacing the concept with more modern tech, it's cost. They are able to provide a cheaper product that meets the needs of most users, but not 100.00% of them.

-J

[RPNerd]

Another thing you might be interested in trying once you get used to your 41CV, and provided your one is what's known as a "fullnut" (as opposed to "halfnut"), is a 41CL CPU board by Monte Dalrymple.

https://systemyde.com/hp41/index.html

It's not cheap by any standards, but provides amazing value for money. In a "nut" shell, what you get with the 41CL if you also go for the optional Time Clone module is:

* a 41CX functional equivalent that can run at up to 50x the speed and already has a full complement (600 registers) of X-Mem
* hundreds of modules ready in flash memory to be "plugged" into the system virtually and used straight away
* The ability to back up the calculator's entire memory space to a page in flash memory so that it survives power loss
* (optionally) a serial port interface allowing you to update the modules in flash and to back up the calculator's contents to a PC/Mac (a lot of work was put into the software to do this by Sylvain Côté if memory serves).

[CheshireChris]

Thanks, everyone. Some very useful information there.

[Frido Bohn]

Hello Chris,

Welcome to this forum!

I had my first contact with the HP calculator/small computer world in 1984 - it's 40 years since then...
The device was an HP-41CV which was barely affordable for a university student in those times in Germany. The US$ to Deutsche-Mark exchange rate was then about 3:1. I spent the first days and nights getting used to RPN and programming following the user guide/manual. The only peripherals I could afford in the time to come was the HP-82162A printer and the HP-IL module that was necessary to drive it. This was a good combo as the printer enabled to document the programs easily. The printouts were a kind of backup should something result into the infamous MEMORY LOST. The 41CV was a was a faithful companion until the early 1990ies when it was superceded by an HP-48G.

To get to the point. I would recommend to approach the HP-41CV step by step and start to understand the basic concepts as they are exellently described in the 'Owner's Handbook and Programming Guide'. As already mentioned above, there is a true cornucopia of extensions and peripherals for this calculator. External storage becomes more necessary when your programs become more complex and longer, and you don't want to key them in every time, or when the amount of programs won't fit any more into the storage capabilities you have. As long as you are far away from such a situation I would keep calm and consider carefully what you actually need. Well, from a collectors point of view you may observe the market and get the items as they appear to be affordable to you.
Apart from original extensions and peripherals there is also a lot of stuff that has been developed only a couple of years ago using nowaday advances in electronics that vastly overcome the limitations of the past. Check for '41CL', 'clonix 41' and 'DM41X' in the net. The latter being a recent clone of the HP-41CX (albeit without HP-IL capabilities).
To answer your question: "HP-41CV Card reader essential?", I'd say 'no'.

Something that was not mentioned already, is the plethora of documentation around the HP-41C. I discovered this in its full extent only in the late 1990ies when the internet became their repository and the means of exchange. The HP-Museum provides a document set of manuals and guides not only for the HP-41C but for practically any 'historical' HP calculator and their add ons. Absolutely worth its money is also the PPC Archive of Jake Schwartz that contains the user contributions to the HP world since the 1970ies. There, you will find treasure boxes such as 'PPC Journal', 'HP Notes' and the 'UK PPC Datafile'. You will get to know celebrities such as Richard J. Nelson, Henry C. Horn and Wlodek Mier-Jedrzejowicz.
The HP calculator universe in general, and the HP-41C in particular, is not only defined by its technical achievements but mostly by its user. Without them, those calculators would merely be neat boxes filled with some electronics. The sould comes from its users who are still active as of today, now for around 50 years since the early beginnings.

Cheers!
Frido

[CheshireChris]

(08-11-2024 10:40 AM)Frido Bohn Wrote:  Something that was not mentioned already, is the plethora of documentation around the HP-41C. I discovered this in its full extent only in the late 1990ies when the internet became their repository and the means of exchange. The HP-Museum provides a document set of manuals and guides not only for the HP-41C but for practically any 'historical' HP calculator and their add ons. Absolutely worth its money is also the PPC Archive of Jake Schwartz that contains the user contributions to the HP world since the 1970ies. There, you will find treasure boxes such as 'PPC Journal', 'HP Notes' and the 'UK PPC Datafile'. You will get to know celebrities such as Richard J. Nelson, Henry C. Horn and Wlodek Mier-Jedrzejowicz.
The HP calculator universe in general, and the HP-41C in particular, is not only defined by its technical achievements but mostly by its user. Without them, those calculators would merely be neat boxes filled with some electronics. The sould comes from its users who are still active as of today, now for around 50 years since the early beginnings.

Cheers!
Frido

Thanks, Frido. I've downloaded the HP-41CV manuals and several other associated books and started reading them, and also this afternoon I sent Jake the money for the PPC Archive - it certainly looks like a treasure trove of information!

I should get my calculator on Tuesday or Wednesday, so I'm really looking forward to it.

Thanks again for the help - it's much appreciated.

Chris