HP Forum Archive 13

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41CX with dead extended memory Message #1 Posted by dbrunell on 20 Sept 2003, 2:18 a.m. I have a 41CX with what appears to be inoperable extended memory. I can try to create a text file with CRFLAS, and no error is reported. Yet nothing shows up under CAT 4. If I try to call the file up by name, I get a "FL NOT FOUND" error. Same result when I try to save/get a program. Is this a common problem? Is it fixable? I've tried clearing out memory. Everything else on the calculator works fine. Halfnuts aren't very repairable, are they? Thanks, Dave

Re: 41CX with dead extended memory Message #2 Posted by christof on 20 Sept 2003, 11:25 a.m., in response to message #1 by dbrunell when you do cat 4 you get 'DIR EMTPY' ? and what is reported in the X register after that? assuming >0, what happens when you enter a simple program with label and end (say, something with 30 lines, like LBL FOO 2 enter enter enter enter + + + + + ....) when you SAVEP after putting FOO in the alpha register, do you get a catalog 4 entry for the program? what number is left in the X register then? have your tried a reset (memory lost, something synthetic might have messed you up, you may even have to do the old batteries out reset)

Re: 41CX with dead extended memory Message #3 Posted by dbrunell on 20 Sept 2003, 8:25 p.m., in response to message #2 by christof Thanks for your reply. Yes, CAT 4 gives DIR EMPTY and 124 in the X register. So it's like the machine thinks it's got a full memory there. When I try to save a program with SAVEP, no errors are generated. It must do a write without verify because if I immediately do a CAT 4 I get DIR EMPTY and 124. When I got the unit, the batteries had been out of it for over a week, so it had time to do a hard, cold reset. I've had the batteries out several times since and did numerous <-/ON clearing operations. I'm guessing that the extended memory (and clock) are on that little board soldered piggyback to the main board. I haven't pulled it off yet, but it doesn't look like there is much that can be serviced on it, save for maybe a shorted capacitor. I'd further guess that the actual rom functions are on the main board, since it has no trouble finding and executing them. Surprisingly, the clock works just fine. Dave

Re: 41CX with dead extended memory Message #4 Posted by Tony Duell (UK) on 20 Sept 2003, 8:49 p.m., in response to message #3 by dbrunell That little daughter board (the 'enhancement assembly') was about the only part of a halfnut you were supposed to replace. It contains 3 chips directly bonded to the PCB -- the timer chip, the ROM with the extran 41 CX functions (12K words, but note the main ROM on the display driver is different between the CV and CX, so you can't turn the former into the latter just by adding this board), and the extended RAM. It's quite possible for the RAM to fail, but the rest of the board to keep on working.

Re: 41CX with dead extended memory Message #5 Posted by dbrunell on 21 Sept 2003, 1:10 a.m., in response to message #4 by Tony Duell (UK) Tony, thanks for the explanation of the enhancement assembly. There must indeed be some sort of internal problem with the RAM chip. The only other components on that board are a crystal and a resistor. It probably wouldn't help to plug in an extended RAM module since the calculator would still try to fill the internal memory first. I'm beginning to get a very negative view of HP these days. I have a number of old TI and HP calcs, and the TIs have proven to be the least troublesome. I've got an 18C with a broken battery door, a 32E where the power switch quit working, a 45 with a broken keyboard, a 12C with a bad LCD, an 82240A printer that doesn't advance the paper properly when a full roll is present, and now a 41CX with bad extended memory. Plus, my HP laptop (not a Compaq design) locks up all the time. Where is this "HP quality" that people speak of? I think I've spent my last dollar on HP products.

Re: 41CX with dead extended memory Message #6 Posted by David Smith on 21 Sept 2003, 3:22 p.m., in response to message #5 by dbrunell Actually, depending upon the failure mode, an external RAM module may even work. If the onboard RAM chip has a bad interface that does not respond and lock up the bus, an external RAM could be OK. I seem to remember a case of a 41CV that had a bad RAM. The guy that had it removed the extra RAM chips and used a quad memory module.

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