foucher@caen.engin.umich.edu (Bradley S Foucher) (02/20/91)
Hello all, My curiosity was aroused when I heard that a 32K RAM card could be had for a mere $23, so I went to the local mall to find one and try it out. I found them at both Sears and Hudsons for $34.99 (I probably should have held out for Wal-Mart, but you know how you get when you decide to spend money you shouldn't be spending - you want to do it quickly!). I told the guy at Sears what I was doing and he suggested that I try them (he had 3) out there before I bought them. The first one I tried gave me "Bad Card Data" when I turned it on. I tried to MERGE port 2 (where the card was) and the calc said port 2 was empty. Dismayed, I decided to try the next one. This one also gave me "Bad Card Data", but MERGE'd fine. I then FREE'd it, removed it, re-inserted it, and tried again, with no problems. I then tried it as a "disk" by storing a file to the FREE'd card, and that worked too. I've had my card for a day now, and I've filled it, ARCHIVE'd it, tested it, etc.. and have had NO PROBLEMS. The only thing I could find different about the two cards I tried was that on the one that didn't work the instructions on the back of the card looked like they were printed on a piece of paper and then glued to the card, whereas my card looks as if the instructions were typed directly on the case of the card. Maybe this is a newer version or something. I may be wrong on this, so be sure to try it out first, and don't blame me if your calc bites you. I didn't even try the 3rd of 3, so I don't have a good idea how many work - you'll just have to try... Since I've had my card I've filled my calculator to the brim with some of those huge programs that I once had to overlook. The Phone Number Manager, by Joe Ervin is a great program, as is the newly posted Gateway version 2.6 by Eric Bryntse. I must also comment on the recently controversial split proposal. I agree with whoever said that HP users shouldn't be the ones to find a new home. I wouldn't mind a split, just as long as it's the others that leave, not HP users (seeing as how they're the ones who want the split in the first place). When the South tried to separate from the North in the Civil War, they didn't say " O.K. We're going to be the new United States, and you guys go and be someone else!" Just my $.02 Brad Foucher The University of Michigan Nuclear Engineering Dept. foucher@caen.engin.umich.edu
akcs.kevin@hpcvbbs.UUCP (Kevin Jessup) (02/21/91)
As I understand it, the RAM cards made by HP and CMT have a special voltage regulator so that they operate properly with the lower voltage on the HP48. Other RAM cards may work if you find one that happens to work with the 48s lower voltage output. I don't know how reliable they will be over time though. Any one else out there, feel free to correct me if I am wrong about this.
jcohen@lehi3b15.csee.Lehigh.EDU (Josh Cohen [890918]) (03/05/91)
Greetings! after reading frechett's post about the smith corona
32k ram cards, I bolted down to the local typewriter repair store and bought
one. Before I give you the tech stuff Ill throw in some humor. well, maybe
When I asked if I could try it out in the store the guy laughed at me and
said "You didn't lug your word processor in here did you?? (ha ha )", so I
said "(ha ha ) no, I didn't ". That's when I whipped out my 48. "huh?
what is that!!?? ". "oh just a calculator....." I smoothly slipped the card
into the slot and turned on the calc. BEEP Invalid card data. The guy said
that he had formatted the card for me {?} I guess for the word processor...
I asked him to get me a different one and he did. I plugged it in and I dont
remember it beeping, but I typed merge 1 and presto 44k ( 11k before) left.
In hindsight I dont know if his formatting screwed anything but I guess
one should avoid it. So far, no problems. The associated problems that I
have been told are as folows {courtesy of frechett} because of a small voltage difference, the epson made (smithcorona too) will crash your calculator
if the batteries IN THE CALCULATOR get real low. moral of the story..
check batteries often. According to him, he put the card in someones low
batt calc and it crashed, but ON C brought it back, no problems ( he did it
5 min before a test, presumable to copy stuff for a friend? ) anyway
you can check your batteries by doing ON D then g..
anyway the card is smith-corona part number S75531 and I paid 32$ for it.
good luck to all, feel free to mail me if you do the same...
jcohen@scarecrow.csee.lehigh.edumichaelv@iastate.edu (Vanloon Michael Lee) (03/08/91)
In article <1991Feb19.214829.22315@engin.umich.edu> foucher@caen.engin.umich.edu (Bradley S Foucher) writes: > My curiosity was aroused when I heard that a 32K RAM card etc . . . I went on down to my favorite Wal-Mart and picked up one of these little guys for $23.84+tax. Unfortunately, the results I obtained were not nearly as rosy. It was sealed up real nicely in a plastic retail package, so I didn't try it right there. When I got it home, I plugged it in and turned the calc on, but all I got was a bleeding screen and absolutley no response from my calc. I had to pull the foot off and push the reset button (not even On-C would bring it to life). Though it shouldn't matter, my calc is a rev D. So, I ran down there and swapped it for another with exactly the same results. As Mr. Foucher reported, one of my cards had the info printed directly on the card, and the other had a stick on plastic label. Same result with both cards, though--no error messages, no response, just a bleeding screen. Any ideas? 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. michaelv@iastate.edu
frechett@spot.Colorado.EDU (-=Runaway Daemon=-) (03/08/91)
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=- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- 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. -==-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
darrylo@hpnmdla.hp.com (Darryl Okahata) (03/12/91)
Here is a reposting of some edited messages concerning RAM cards.
This should probably be posted in a FAQ list.
It is possible to seriously damage your HP-48SX.
-- Darryl Okahata
UUCP: {hplabs!, hpcea!, hpfcla!} hpnmd!darrylo
Internet: darrylo%hpnmd@relay.hp.com
DISCLAIMER: this message is the author's personal opinion and does not
constitute the support, opinion or policy of Hewlett-Packard or of the
little green men that have been following him all day.
===============================================================================
From steveh@hpcvra.CV.HP.COM Fri Mar 1 17:00:00 1991
From: steveh@hpcvra.CV.HP.COM (Steve Harper)
Date: Fri, 11 May 1990 16:52:07 GMT
Subject: Re: Memory Card: Give Us *True* Facts! (Was Re: HP48SX Memory Card Pricing)
Organization: Hewlett-Packard Co., Corvallis, OR, USA
Newsgroups: comp.sys.handhelds
My previous statement that under certain circumstances the
calculator may even be damaged electrically is not a ploy.
If the calculator's internal power supply voltage happens to
be near the low end of the range, say 4.1 V, and the voltage
at which the card's voltage control chip shuts it down
happens to be near the high end of its range, say 4.2 V (this
can and does occasionally occur for the non-HP48SX cards),
then the calculator will start to drive the memory address
lines and the card will still have these clamped to ground
(that's what it does to protect itself when there is not
sufficient system voltage to run). This unfortunate situation
may simply trash your memory, or if the calculator tries
to drive enough of the lines high at the same time, several
hundred milliamps may flow...for awhile that is, until something
gives up... On the other hand, your calculator and a particular
non-HP48SX card may work just fine if those voltages happen
to be at the other end of their ranges. These voltages are
also slightly temperature sensitive. It may work in the
classroom or office and not at the beach, or vice versa.
The voltage trip point of the HP48SX cards has been set
lower (a different voltage control chip) so that this cannot
occur, regardless of part and temperature variations.
One other item was brought to my attention yesterday by
Preston Brown that I should have included in my original
posting here. While most of us recognize that comparing
ram cards to a handful of dynamic ram chips to plug into
your PC is apples and oranges, it may be more interesting
to compare the HP48SX cards with cards for other products,
like the Atari Portfolio, the Poquet, the NEC Ultralite,
etc. I believe you will find that the prices on the
HP48SX cards are not at all out of line.
Steve
"I claim all disclaimers..."
the non-HP48SX cards
===============================================================================
From prestonb@hpcvra.CV.HP.COM Fri Mar 1 17:00:00 1991
From: prestonb@hpcvra.CV.HP.COM (Preston Brown)
Date: Thu, 17 May 1990 17:26:53 GMT
Subject: Re: Memory Card: Give Us *True* Facts! (Was Re: HP48SX Memory Card Pricing)
Organization: Hewlett-Packard Co., Corvallis, OR, USA
Newsgroups: comp.sys.handhelds
When the RAM cards detect that voltage is to low to operate they
clamp the address lines to ground. This clamping is done by turning
on the output drivers of a custom chip included on the card. The
clamping current is speced at 2mA min at the Vol output level. Since
the 48 can be trying to drive the line all the way high even more
current is typical. 10mA per fight is not uncommon with totals of
several hundred mAs.
The VDD power supply is regulated at 4.1 - 4.9 with typical
parts at the low end (4.3). The power to the cards is switched
thru a transistor, creating up to a 0.1V drop. Standard Epson
cards have a significant chance of seeing this voltage as
to low and shutting down. We have seen cards do this in the lab.
When it occurs the calculator locks up with VDD pulled down
to about 2.5V and 250mA being drawn from the batteries. This
current drain greatly exceeds the ratings for the power supply
and can dammage your calc. The least that will happen is a loss
of memory.
Now, why didn't we regulate VDD higher?
The 48 has two power supplies VDD at 4.3 and VH at 8.5. VH
cannot be regulated higher without exceeding the spec for
our CMOS IC process. VH is used as the + voltage for the I/O.
In order to meet a +3V output level VH must be more then 3.6V
above VDD. (VDD is used as I/O ground). Our power supply
system increase the battery life and reduces the cost greatly
for the wired I/O.
Preston
And with all disclaimers: