Path: utzoo!mnetor!tmsoft!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!sdd.hp.com!elroy.jpl.nasa.gov!decwrl!shelby!msi.umn.edu!noc.MR.NET!nic.stolaf.edu!uafhp!mamos From: mamos@uafhp.uark.edu (Mark _E_ Amos) Newsgroups: comp.sys.handhelds Subject: Re: Interesting effect (HP48) Message-ID: Date: 16 Feb 91 07:03:31 GMT References: <59716@eerie.acsu.Buffalo.EDU> Sender: news@acc.stolaf.edu Organization: University of Arkansas, Fayetteville Lines: 64 As long as we're on the subject of RAM problems and lockups, I would like to share my latest adventure, in the hopes I can learn just what the H*LL is happening. -Some guys I know in my department discovered they could use Smith-Corona 32K RAM cards ($23.84, local Wal-Mart) in their 48's. Out of 3 purchased, 1 didn't work, and a quick exchange at the store fixed that. Here comes the fun part: A friend and I figured we'd cash in on this cheap expansion stuff, and after discovering the local Wal-Mart was sold out (word gets around, eh?) we went to one at a neighboring town, finding plenty of new and unopened blister packs of the little jewels. I bought 2 and my friend bought 1. Upon reaching the car, I got my 48 out and plugged 1 of mine in - it worked great! I then plugged the second one in and turned on the power to see random vertical lines, then blank screen, then a BLACK screen which began bleeding and pulsating from left to right, with NO key sequence having any affect at all. The bleeding screen smacked of overdrive, so I unplugged the second card. The machine then came back after a bit of a wait and key pressing. -Ok, fine, I happened to get a bad card like the other dude I knew... So, I tried my friend's card - same exact thing. This happened with the two "bad" cards whether I had the "good" one in or not, and didn't matter which slot. Now what? Try them on my friend's machine - they ALL 3 worked flawlessly, including two at once... -Hmmm. Well, I had about 28k used on mine, including a library in port 0, so I copied all my stuff to his and duplicated the above sequence. Same result. Next I tried checking ROM versions, etc.-identical (D). I then began grabbing for straws - wiped my machine (ON-A-F, No) and tried again: same thing. OK, he had his old original batteries and I had brand new ones (NOW we're grabbing for shadows of straws) so I swapped them - same result. (Incidently, the ON-D, G sequence does NOT seem to have any indication of relative battery strength WHATSOEVER, as I checked this during the process). -I finally gave up and went back in to exchange one of the "bad" cards, hoping I would get lucky and get one that would work on mine like the one I had that would. No such luck. This one also worked fine in my friend's but did the bleeding screen bizness on mine. -I have been an electronics tech for upwards of 8 years, and an engineering student for 2 years so far - I consider my methods logical and thorough, yet I can find NO explanation whatsoever for this "phenomena". I will be sending my machine in to update ROM to E in a few months, but in the mean time, what in the name of Sam Hill is happening? I know, I know, it's not an authorized HP card, etc., etc. - but the fact remains 3 of 4 cards would NOT work on MY machine, yet 7 of 8 work on 3 other machines - the 8th of which I have yet to discover the actual symptoms of (ie. screen bleeding, or just no workum?). -Conclusion: authorized RAM card or no, there are obiously SOME kind of differences between machines that are ROM independent. OK, so let's talk about the variations in line drivers/buffers, etc. -I know these differences exist, but what I would like to know most of all is, am I just the fluke or does this kind of thing happen to anyone else out there? "Curiouser and curiouser..." ============================================================================== Mark _E_ Amos | University of Arkansas Computer Science Engineering mamos@uafhp.uark.edu | mea1@engr.uark.edu | (emphasise the Computer Engineering please) ------------------------------------------------------------------------------ "Man's mind, when stretched to a new idea, never goes back to its original dimension." -Oliver Wendell Holmes ==============================================================================