|HP 41C data storage integrated circuit swapping: Maybe Eric could answer this ;-)|
Message #1 Posted by Geoff Quickfall on 17 Mar 2010, 3:44 a.m.
I posted this many months ago and cannot find it in the archives. I know Eric Smith had many good answers including swapping the memory with a 41CV. I just can't find the info so here is the question again
Here is a photo of an early HP 41C with all the bugs and also with a defunct D/S integrated circuit (RAM) (ser# 1931Axxxxx). It is the one at the bottom right labelled:
When SIZE 000 is executed the program registers available equal 47 out of the required 63. All programs execute and the data registers used for STO when SIZE 047 is executed are accessable. This indicates that (my logic) the last D/S chip is unserviceable and must be replaced:
My quandry is that I have a newer HP 41C board (1981) with the following chips. They have the following codes from first to last:
1LB740 (this chip is in the same position as the chip on the
My assumption is that the last chip; 1LB740 would be the one to use. My question is, is it swappable with 1LA705.
I also have a two CV's with similar blocks of 5 D/S chips:
1LE704 this chip is in the same position as the chip on the
1LH505 (this chip is in the same position as the chip on the
My questions are as follows:
1. is my assumption correct and the last D/S chip is the
defunct chip on the photo above; chip 1LA705?
2. Which chip in the 3 lists above are swappable;
1LB740, 1LE704, 1LH505 or any of the others?
The reason for doing this, to keep the early with bugs board intact with its bugs. That precludes me just swapping out the board for a newer one which I have. That is I would like to use a donar chip from the three options above to replace the bad chip that I hopefully have identified correctly.
Thanks in advance, Geoff
Edited: 17 Mar 2010, 3:51 a.m.