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X-memory Data with the card reader
04-13-2015, 06:10 PM
Post: #1
X-memory Data with the card reader
First, I would like to say thanks to the board administrators and the people who post here. You have helped me rediscover my languishing HP-41.

Rediscovering the "Memory Lost" message a couple of times reminded me why I was so careful to document and save important programs. Now that I have my card reader up and running again with O-rings on the feed roller, thanks in part to this site, I am feeling less nervous about recovering from a Memory Lost message. Except...

I have a program I wrote that uses a 72 record data file in extended memory. I wrote a little program that uses the wand to directly load barcode numbers into EM. From my understanding of the card reader manual it is not as straight forward with the card reader. The only way I can think to recover the data file with the card reader is to first load the data into memory using RDTAX or RDTA and then move that data to extended memory. Not a big deal until the data file space is restricted by program memory, then it becomes more of a pain.

Has anyone developed a way of using the card reader to directly load into Extended Memory?
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04-14-2015, 06:23 AM (This post was last modified: 04-14-2015 06:26 AM by Dieter.)
Post: #2
RE: X-memory Data with the card reader
(04-13-2015 06:10 PM)4ster Wrote:  Has anyone developed a way of using the card reader to directly load into Extended Memory?

No way. On the one hand the card reader allows exchanging data between RAM and "mass storage", i.e. magnetic cards. On the other hand the X-Functions transfer data between RAM and X-Memory. So there is no direct link between cards and X-Memory.

You should also keep in mind that the X-Functions/X-Memory module (as well as the 41CX) appeared some time after the HP-41 and its card reader, so the latter of course did not include any functions for reading/writing data directly from/to X-Memory.

By the time X-Memory was available HP introduced HP-IL with its much more powerful tape drive as a kind of file-based "next gen" mass storage. AFAIK X-Memory files could be transferred directly to/from this device. OTOH I feel the card reader was more like an intermediate solution for using HP67/97 software. While 224 bytes per card were fine for a 67/97 (one card could hold the complete program memory or all data registers), it was quite a bit limiting for the '41. ;-)

Dieter
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04-14-2015, 03:45 PM
Post: #3
RE: X-memory Data with the card reader
Thank you Dieter for confirming my suspicion. Makes sense to me.

As I thought about it some more this isn't too much of a problem. Since the program in question is the primary program I use on the HP-41, it will be the first one reloaded after a "Memory Lost" so there is memory to spare for the data file to be loaded by the card reader. I've also got my backup wand program that scans directly into Extended Memory if the memory is filled with programs and there isn't enough room for the data file.
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04-14-2015, 09:31 PM (This post was last modified: 04-14-2015 09:32 PM by Garth Wilson.)
Post: #4
RE: X-memory Data with the card reader
(04-13-2015 06:10 PM)4ster Wrote:  Rediscovering the "Memory Lost" message a couple of times reminded me why I was so careful to document and save important programs.

Do you know why you got the message? The only times I ever got it was when I was new to synthetic programming in the 1980's. I've never had that message since then, and I have had certain programs I use frequently resident in the 41 continuously for 25 years, never having to re-load them. I have a couple of the tape drives, but I have not connected my 41 to one in many, many years.

http://WilsonMinesCo.com (Lots of HP-41 links at the bottom of the links page, http://wilsonminesco.com/links.html )
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04-15-2015, 06:40 AM
Post: #5
RE: X-memory Data with the card reader
I've had two "Memory Lost"s in the last few weeks. Both events happened without the "BAT" annunciator showing up. The first time the HP emitted some unusual tones and it threw me off. I kept trying to start it and the display wouldn't come on, just beeping, then the dreaded message. The other one was a surprise too, but no beeping.

In the past, using alkaline batteries, I have run the calculator for a couple of years until the "BAT" appeared then changed the batteries. (It has been lightly used for about a decade.)

There was a slight hint of corrosion on the battery holder's springs. I think that may have been the problem. I cleaned them with electrical contact cleaner (DeOxIt), so far so good. Fortunately the foil contacts look good.
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