Re: Best way to test HP-71B RAM modules (the 32K/96K ones etc.)? Message #3 Posted by Philippe Lasnier on 24 Sept 2013, 6:12 p.m., in response to message #2 by Hans Brueggemann
Thanks Hans,
Unfortunately I have neither the DIAGNOSTIC module nor the MATH module. As for assembly, I would need to learn, get an emulator, an assembler, download the program... I'm sure it could be fun, but I've never done it, and for this exercise this is not worthwhile - I only need to test a couple of modules!
So, the slow way with a BASIC program. Oh dear...
Well, in a way this was fruitful: I wrote a small BASIC program that would ask for an integer array size, define the array, fill it with 88888, then check it was filled properly. I would have then added setting and checking for 0, or 11111, whatever, but as it turned out, just this was enough to detect that my 96 KiB module was broken: as soon as I ran the program asking for 38000 entries in the array (~111 KiB used), the HP-71B blinked, then displayed "Memory Lost". I re-entered the program, then slowly re-tested by entering larger and larger size values. 35000 was ok, 36000 was ok, 37000 - Memory Lost again.
I don't have a memory map for the HP-71B (I'm sure I'd seen it somewhere though...), but I would hazard that some stack memory ended up in that module's space, proving indirectly that the module was fried. Oh well.
My 32 KiB module on the other hand seems to be faring well: if I allocate the array with increasing sizes, it eventually politely tells me "ERR:Insufficient Memory"; it doesn't reset the machine! The program ran and successfully checked that each array entry is equal to 88888 (I'll run more tests with various values later).
That's not a full test really (checking for all bit changes and persistence etc.), but I guess that will have to do.
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