creiman@ncsa.uiuc.edu (Charlie Reiman) (04/18/91)
Does anyone know how long the HP48's memory remains intact with the batteries out? I only ask because one of the guys/dudes/hombres I live with recently took the professional engineer's exam (something like that). They were allowed as many books as they could carry and a calculator. The only trick was that you had to pull the batteries out of the calculator once to clear the memory. As we all know, this doesn't do diddly to an HP, unless you leave them out for XX time. I suddenly began to wonder, just what is XX for the 48? On a related note: I haven't replaced my batteries since I bought my machine, in december. The battery alarm has never turned on, so I never bothered. Should I panic and replace them anyway? -- Charlie Reiman creiman@ncsa.uiuc.edu Definintion of clarity, UNIX style: usage: ls -RadCxmnlogLrtucpFbqisfS [files]
berg@marvin.e17.physik.tu-muenchen.de (Stephen R. van den Berg) (04/18/91)
Charlie Reiman writes: >Does anyone know how long the HP48's memory remains intact with the batteries >out? Talking about removing the batteries... What happens to any plugged in memory expansion cards? Do they get drained, or do they simply shut themselves off? (I guess the latter, but can anybody confirm this?) -- Sincerely, berg@marvin.e17.physik.tu-muenchen.de Stephen R. van den Berg. "I code it in 5 min, optimize it in 90 min, because it's so well optimized: it runs in only 5 min. Actually, most of the time I optimize programs."
stevev@greylady.uoregon.edu (Steve VanDevender) (04/18/91)
In article <1991Apr18.052937.7060@ux1.cso.uiuc.edu> creiman@ncsa.uiuc.edu (Charlie Reiman) writes:
Does anyone know how long the HP48's memory remains intact
with the batteries out?
The manuals recommend that you change batteries within two
minutes to avoid memory loss.
I only ask because one of the guys/dudes/hombres I live with recently took
the professional engineer's exam (something like that). They were allowed
as many books as they could carry and a calculator. The only trick was that
you had to pull the batteries out of the calculator once to clear the
memory. As we all know, this doesn't do diddly to an HP, unless you leave
them out for XX time.
Ha! Ha! Ha! Even if they made him take the batteries out for
more than two minutes, what do they do if he has a Solve Equation
library card and a freed 128K RAM card with all kinds of things
stored in it? Clearly the professional engineer examiners aren't
keeping up with modern technology. And if he can take all the
books he can carry, he could have far more stored in those than he
could ever have in a fully-loaded HP-48.
--
Steve VanDevender stevev@greylady.uoregon.edu
"Bipedalism--an unrecognized disease affecting over 99% of the population.
Symptoms include lack of traffic sense, slow rate of travel, and the
classic, easily recognized behavior known as walking."ebergman@isis.cs.du.edu (Eric Bergman-Terrell) (04/19/91)
I don't think removing the "main" batteries from a 48SX will affect the memory cards as they have their own batteries. Terrell
cb377760@longs.LANCE.ColoState.EDU (Curtis Brown) (04/19/91)
Speaking of which, has anybody tried to hardwire this puppy with an external power supply? I happen to have one of those SC timebombs in my calc and (silly me for thinking) thought it would be nice to have backup power. The thing I can't figure out is how to open the dumb thing. Any and all input great appreciated!! ------------------------------------------------------- Curtis Brown self-claimed EE student cb377760@longs.LANCE.ColoState.Edu "So THAT'S what an invisible force field looks like!" -------------------------------------------------------
sjthomas@cup.portal.com (Stephen J Thomas) (04/19/91)
Any RAM cards installed in a 48 are powered by the 48's batteries ONLY WHEN THE 48 IS TURNED ON!! When the 48 is off, or the card is removed, the card is powered by the card's own battery. Forgetting to turn the 48 ON when changing a RAM card battery is a sure way to loose everything stored in the card. ---"The voice of experience. Learn from my mistake!" Stephen Thomas sjthomas@cup.portal.com
benji@pnet01.cts.com (Brad Pennock) (04/19/91)
creiman@ncsa.uiuc.edu (Charlie Reiman) writes: > > >Does anyone know how long the HP48's memory remains intact with the batteries >out? > >I only ask because one of the guys/dudes/hombres I live with recently took >the professional engineer's exam (something like that). They were allowed >as many books as they could carry and a calculator. The only trick was that >you had to pull the batteries out of the calculator once to clear the memory. >As we all know, this doesn't do diddly to an HP, unless you leave them >out for XX time. > >I suddenly began to wonder, just what is XX for the 48? > >On a related note: I haven't replaced my batteries since I bought my >machine, in december. The battery alarm has never turned on, so I never >bothered. Should I panic and replace them anyway? >-- Remembering what the manual says I believe you have approximately 2 minutes to replace the batteries once you remove them. As I see it there are two things you can do... 1) Get a RAM card (one of those Smith-Coronas would be good) and put your stuff in there. 2) Hope he doesn't wait more than 2 minutes before allowing you to replace your batteries. If your calculator isn't dimming or acting weird, don't worry about your batteries! I'd mind what the indicator is telling me if it does come on though. Good luck on your tests, I couldn't think of a better friend to take it with you than a 48SX, a true engineering/science student's dream! UUCP: {hplabs!hp-sdd ucsd nosc}!crash!pnet01!benji ARPA: crash!pnet01!benji@nosc.mil INET: benji@pnet01.cts.com
herman@corpane.uucp (Harry Herman) (04/19/91)
In <4241@rwthinf.UUCP> berg@marvin.e17.physik.tu-muenchen.de (Stephen R. van den Berg) writes: >Charlie Reiman writes: >>Does anyone know how long the HP48's memory remains intact with the batteries >>out? >Talking about removing the batteries... What happens to any plugged in >memory expansion cards? Do they get drained, or do they simply shut >themselves off? (I guess the latter, but can anybody confirm this?) >-- >Sincerely, berg@marvin.e17.physik.tu-muenchen.de > Stephen R. van den Berg. >"I code it in 5 min, optimize it in 90 min, because it's so well optimized: >it runs in only 5 min. Actually, most of the time I optimize programs." I believe the calculator can maintain its own memory for about 2 minutes with the batteries removed. This is so you have time to put new batteries in. As concerns the RAM cards, each card has its own built in battery that is supposed to last 5 years. When the calculator is shut off, or the cards are removed from the calculator, there is a chip on the cards that isolate them from the HP48 until such time as they detect 4.1V or more on the power supply pins again. Harry Herman herman@ukma!corpane
persol@solan.unit.no (Per Solberg) (04/19/91)
In article <1991Apr18.052937.7060@ux1.cso.uiuc.edu>, creiman@ncsa.uiuc.edu (Charlie Reiman) writes: |> Does anyone know how long the HP48's memory remains intact with the batteries |> out? |> |> ... you had to pull the batteries out of the calculator once to clear the |> memory. As we all know, this doesn't do diddly to an HP, unless you leave them |> out for XX time. |> |> I suddenly began to wonder, just what is XX for the 48? |> |> Charlie Reiman creiman@ncsa.uiuc.edu Before shipping my 48SX-A off to HP for upgrading to rev. E last week, I tried to find out how long I could leave the batteries out without losing memory. I started my removing the batteries, leaving them out for 5 minutes and then reinserting them. As expected, memory was intact, so I tried again, this time for 10 minutes. Then I tried for 15, 20, 25 and 30 minutes and still no loss of memory. As I had grown tired of trying, I decided not to investigate the matter further. Answer : XX > 30 minutes. I have only tested this on my own 48SX with no RAM/ROM-cards, and I don't know if adding RAM/ROM-cards will have any effect. Per Solberg persol@solan.unit.no
s2499576%techst02.technion.ac.il@TAUNIVM.TAU.AC.IL (Yaniv Shaya) (04/20/91)
As much as I can remember, in the manual it is stated that the computer memory will last for (at least) 60 seconds - not very much, but then maybe I am wrong.
gimbel@athena.mit.edu (William A Gimbel) (04/22/91)
In article <9104201150.AA08143@techst02.technion.ac.il>, s2499576%techst02.technion.ac.il@TAUNIVM.TAU.AC.IL (Yaniv Shaya) writes: |> As much as I can remember, in the manual it is stated that the computer memory |> will last for (at least) 60 seconds - not very much, but then maybe I am wrong. The company, in this case HP, will always put a conservative estimate of the amount of time you have to replace the batteries in your calculator. I reality it could be anywhere from zero seconds to a whole day or more. Of course I am exaggerating, but I hope the point is clear. You will never know the exact time for your calculator unless you experiment, and are willing to wipe out memory at least once. (You could probably get a more realistic estimate also from HP if you are concerned with the actual amount of time.) -- Bill
jcohen@lehi3b15.csee.Lehigh.EDU (Josh Cohen [890918]) (04/22/91)
I am not exactly sure but a common way to do that is with a capacitor.. a slow decay, hi energy type. you can keep the calculator off for the duration of the decay period of the capacitor. jcohen@scarecrow.csee.lehigh.edu