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From: frechett@spot.Colorado.EDU (-=Runaway Daemon=-)
Newsgroups: comp.sys.handhelds
Subject: Re: Smith-Corona 32K RAM cards
Keywords: HP48SX, Smith-Corona, RAM cards
Message-ID: <1991Mar8.060824.264@csn.org>
Date: 8 Mar 91 06:08:24 GMT
References: <1991Feb19.214829.22315@engin.umich.edu> <1991Mar8.035532.13342@news.iastate.edu>
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In article <1991Mar8.035532.13342@news.iastate.edu> michaelv@iastate.edu (Vanloon Michael Lee) writes:
>error messages, no response, just a bleeding screen.  Any ideas?
Ok, let me see if I can get this all clear.  This is how I interpreted the 
various tech posts on this subject right after it was brought up.  
EPSON makes the cards for HP and for SC.  As the cards come from the factory
they have a low voltage protector.  This means that if the supply voltage from
the calc drops below a certain level, the card freezes the pins.  The calc can
no longer run the card at all.  Now the problem is that the cards that HP uses,
they replace the factory low voltage protector with one that works at lower
voltage level ranges.  The factory devices cut off at a voltage relatively
close to the normal operating range of the calc.  They also vary somewhat from
one card to another.  

So you managed to find a card with a relatively high level voltage protector. 
When you put in in your card, and turned it on, the voltage output of the calc
was low and the card froze the pins.  The calc is now freaked out because it is
trying to bring up the voltage level on the pins and it just can't.  I suspect
this may also put some very heavy drain on the calc batteries and one of the
things that you see is a bit of hardware messiness.  You see this as the famous
screen dissolving and the calc locking up.  A very nasty state to be sure.
There are three ways that I see to avoid this.
1. Don't get the card.  Since I was lucky, I don't go by this one.
2. Before you go to buy the card, back up the calc.  Take a paper clip. When
you are there, insist that you try the card there.  I did, and there was no
problem.  If it freezes, pull the card FIRST thing.  Reset the calc, and 
hopefully you will find a good one on the next try.   I know that this is not
good for the calc so take it easy.. (don't know what else to say)
3. Modify the card.  (See a previous posting regarding this)  

>Incidentally, as far as I know, my batteries are ok.  And, after I hit the
>reset button (I tried the cards and reset several times) I had no problems
>with lost memory; everything still seemed to be intact.
You might check the batteries though.  5 minutes before a test, I wanted to
transfer some data to a friend's calc.  I plopped the card into his calc and
turned it on.  It froze.  ON-C didn't work.  ON-A-F didn't work.  We scrambled
around and stumbled on a paperclip somewhere and reset it.  BEEP Try to recover
memory?  I said no to save time.  I realize now that he correct procedure
after it locked should have been, remove RAM card, remove EQ card, reset
button.  I find that the reset button is much more forgiving that ON-A-F.  

I asked my friend when he had last replaced the batteries.  He said never.
(Look of awe)  He had had batteries that were VERY old.  After he replaced the
batteries and before he recoverd memory, I tried the card and it worked fine. 
I think his was an extreme case.
>
>michaelv@iastate.edu

So that's the scoop as I perceive it.  

	ian

-=Runaway Daemon=-

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Not so standard disclaimer. (for me)  I take no responsibility for 
any damage that you may incur upon your calculator as a result of 
using information in this post.  Use it at your own risk as I will 
send complaints straight to the round file, a.k.a. /dev/null.
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