What do you keep on your 42S?

[Dave Britten]

(10-30-2019 04:44 PM)Jeff O. Wrote:  Of course the big disadvantage of the original 42S is the inability to upload/download programs, i.e., all programs must be manually keyed in, and are subject to loss if you lose memory for some reason. So, based on the above listing, I really admire your key-punching prowess!

Someone needs to figure a way to at least download. Any way to connect to that 32k ram chip and write to it? (Please forgive the ignorance of this question if it is indeed impossible. My knowledge of such things is obviously quite limited.)

Yeah, that's why I certainly don't plan to fill it with a solid 32 KB of program code! Right now I'm at 19,978 bytes free, and that's with a handful of small matrices containing medical data. I don't think I'll need to add too many more programs, so most of that will just be set aside for data and scratch space.

I saw an old forum post somewhere the other day that talked about adapting the IR circuit in the 42S (and I think 28S) into a receiver, and noting that it can be done. The problem, of course, is how to actually handle the incoming data. It would presumably require poking in a rather complex Saturn assembly language routine using the memory browser.

Tapping the RAM chip's pins and writing into it directly would be way beyond my electronics expertise, but I think the two main challenges to that approach (ignoring the obvious physical challenges of simply wiring up the pins) would be potentially needing to temporarily disconnect/isolate the chip from the calculator while accessing its contents, and also making sure the calculator can provide enough power to the RAM chip while it's turned off, since reading/writing will use more current than standby.