CMT 64K RAM strange behavior (HP-71B) Message #1 Posted by Mike on 25 Dec 2003, 8:53 a.m.
Ok, this is wierd. I haven't ever noticed this before. I have a few CMT 64K RAM modules that all behave as though they are battery backed up. These are the 64K RAMs that plug into the front ports and not the card reader.
When I first got these, I plugged them into a 71B but the 64K RAM didn't show up on my system when I executed MEM function. I traced this to the fact that these RAM modules were configured as independent memory or ROM. That is strange as the memory should have been cleared after being unplugged for so long. They appeared to be ROM.
I thought they might be mismarked as they came unpowered (not in 71B) but already had programs on them. They were used in a system as independent RAM. They have been unpowered for over a week (perhaps months) and the programs are still in the RAM.
I tried deleting one of the programs and it deleted ok. I then took another identical RAM and copied the deleted program from the 2nd RAM back to the first RAM. No problem; it copied fine. So, it is definitely RAM.
Then I created a test program and wrote it to the 1st 64K RAM. Again, no problem, it copied fine. I removed the RAM and let it sit for a day or so and plugged it back in. The program was still there.
I tried this same thing in some of my CMT 32K RAMS and programs were lost immediately. Programs are lost so quickly, on a CMT 32K RAMs, that I can't even quickly move one from port 1 to port 2 without losing data. But the CMT 64K RAMs are holding data days, weeks or longer.
Does the CMT 64K RAM have a battery inside? I know it is sealed so that seems unlikely. Besides how could one change it if it did?
Could this be modified? Or, is this just normal behavior for a CMT 64K RAM module?
Edited: 26 Dec 2003, 12:21 p.m. after one or more responses were posted
|