Hi;
the IC´s you want to search for are RAM IC´s, and these ones are in number of five (64 * 5 = 320). If you remove all of the 8-pin DIP IC´s you will see that five of them have the same prefix (usually ILE7xx) with the last digit being counted 1 to 5. They store 64 registers each, and the first one (lower numbered) relates to the HP41C basic memory. The other four relate to the Quad Memory Module, for instance.
If your HP41CX sees 192 registers (156 + 36, considering that the 3 bytes for the permanent .END. are counted as one less register), it means that the fourth RAM IC is faulty (ILE704). Interesting: I had two HP41CV´s in the same circumstance: the fourth RAM IC faulty.
If you want to confirm with a single test, provided that you have a single Memory Module, with the calculator OFF (could not miss mentioning that) insert it in port #3 and check if the memory count goes OK, then. If you do not have a single Memory Module, try this (I am not sure if this is the correct procedure, just have none of the faulty calculators at hand now):
- perform SIZE 191
- key in 256 (or any number from 256 to 319)
- try VIEW IND X
If I am not wrong, it will give no error message. But I cannot guaranty, OK? Consider that you have an HP41C with two modules, then you perform SIZE 191, then you insert a memory module in the fourth port. That´s what we achieve with the procedure above. So, the last 64 registers are available and there is a gap related to port #3.
Let us know how it goes.
Cheers.
Luiz (Brazil)
Edited: 23 Feb 2010, 10:51 a.m.
