HP41CX Memory

[Bballreich]

I feel like this is a rookie question, but I really don't know the answer, so here it is. If you have an HP41CX, additional memory modules are unnecessary as the calculator already has the maximum amount of memory already internally, correct?

[Garth Wilson]

The cx's main memory is full, but the EXTended memory is not, and it can handle a couple of XMEM modules.  There are modern modules that extend the 41 far more than what was available in the first decades of the 41.  One of them is the 41MAXX module which is (was?) expected to become available this year, 2024.  There's a forum topic about it at https://hpmuseum.org/forum/thread-20991.html, a video at https://www.youtube.com/watch?v=bh9x7D1IjjQ, and a .pdf at https://www.systemyde.com/pdf/maxx-4d_manual.pdf .

[Monte Dalrymple]

(07-16-2024 08:26 PM)Garth Wilson Wrote:  The cx's main memory is full, but the EXTended memory is not, and it can handle a couple of XMEM modules.  There are modern modules that extend the 41 far more than what was available in the first decades of the 41.  One of them is the 41MAXX module which is (was?) expected to become available this year, 2024.  There's a forum topic about it at https://hpmuseum.org/forum/thread-20991.html, a video at https://www.youtube.com/watch?v=bh9x7D1IjjQ, and a .pdf at https://www.systemyde.com/pdf/maxx-4d_manual.pdf .

MAXX beta testing is complete and I hope to put up the order form before too long. I am trying to get a batch of 41CLs out the door at the moment. The current manual is -5A.

[Bballreich]

Garth, Monty, thanks very much for the reply. So, if the CX can handle a couple of Xmem modules, and each module contains 238 registers, then total available memory would be 320 + 238 + 238 for a total of 796 registers? Again, I'm new to all this stuff, so please be patient with me! Thanks again for the help!

[KimH]

Your math is not quite correct the 41CX has the 319. XF Module has about 128 registers plus each module with 238, but it is important to note that the X-Mem acts a bit like a built in storage as if it was a “Disc Drive” - the commands in the X-Functions let you get and store data and programs, but it is not an extension of the 319 registers available as main memory. 41 Brochure take a look at p11

[Garth Wilson]

(07-17-2024 02:15 PM)Bballreich Wrote:  Garth, Monty, thanks very much for the reply. So, if the CX can handle a couple of Xmem modules, and each module contains 238 registers, then total available memory would be 320 + 238 + 238 for a total of 796 registers? Again, I'm new to all this stuff, so please be patient with me! Thanks again for the help!

As Kim says, EXTended memory is more like an internal hard disc, unlike main memory (although there are modern modules that change that).  Main memory is 319 registers (with 7 bytes per register), and the Extended-Functions/Extended Memory module that's built into the cx gets you started with 124 registers of extended memory and you can add two more modules of 238 each, for a total of 600 registers of extended memory.  Again, this is separate from the 319 registers of main memory.

I had the good fortune of coming across a double extended-memory module on eBay years ago for a good price.  EduCALC (and perhaps another distributor or two) used to sell a few different combined modules, and I also got a combined HP-IL/Extended-I/O module when I bought my first 41cx in 1986.  These of course save ports; but today there are ones that let you have lots of ROM module images in the flash memory of a single module.)

There are others on this forum who know the 41's insides a thousand times as well as I do.  I'm just an intensive user who got into the 41 originally as a handheld controller for equipment on the workbench.  You can see my story at http://wilsonminesco.com/HP41intro.html .

[Bballreich]

Garth, thanks so much for the very informative reply. I started my programming hobby with a TI-59 back in high school. I have been interested in the 41cx for quite some time and a "lot" that included what looked like a brand new 41cx came up on Ebay a while ago so I jumped on it. Still learning a ton about what it can do, and it can do a lot!! Thanks again. Take care. Brad

[Garth Wilson]

I started with a 58c, and soon needed more memory, and was at the right place at the right time to trade it plus $100 for an almost-unused 59 plus printer and a few modules and applications books.  Soon the 59 didn't have enough memory either, and I had programs that would prompt for another card, kind of like disc-swapping, for a program with 1500 steps.  The 41cx was a few years later.

[Bballreich]

Cool story and much the same as mine. I had the printer too and created a game program called starhawk that was 10 cards long. I was in the process of debugging in college when I started programming the UC Davis mainframe for some statistical analysis. I never got around to finishing the program and ended up selling the 59 a few years ago. Since then, I found a pristine HP67 and have managed to collect all of the program pacs with the exception of the EE pac. The Nuclear Medicine pac the I purchased was actually used to help east German athletes properly dope so they could get around the doping controls! At least, that's what the owner of the pac said!

[rprosperi]

(07-18-2024 02:29 PM)Bballreich Wrote:  Cool story and much the same as mine. I had the printer too and created a game program called starhawk that was 10 cards long. I was in the process of debugging in college when I started programming the UC Davis mainframe for some statistical analysis. I never got around to finishing the program and ended up selling the 59 a few years ago. Since then, I found a pristine HP67 and have managed to collect all of the program pacs with the exception of the EE pac. The Nuclear Medicine pac the I purchased was actually used to help east German athletes properly dope so they could get around the doping controls! At least, that's what the owner of the pac said!

Calibration tip - was he also selling a bridge?

Anyhow, he accomplished his goal (you bought it) and now you both have a good story.