<kevtris> well, you may want to talk about how an EPROM works first in
		  basic terms

<kevtris> here's how an EPROM works:  the EPROM is arranged as a bunch of
          individual memory cells that can hold a "1" when not programmed,
          or a "0" if programmed

<kevtris> the data is stored on the gate of a transistor; to program the
          EPROM, you inject electrons into the gate, where they get
          stuck.  An ultraviolet light erases the EPROM, because it lets the
          electrons "leak" off the gate

<kevtris> Since no insulator is perfect, these electrons will eventually
          "leak" off, so the cell reverts back to an erased state, taking
          the data with it

<kevtris> the datasheets typically specify a 10 year guaranteed minimum
          programming lifetime

<kevtris> Hower, 20-25 years is about what they usually last

<kevtris> heat, ultraviolet light, and other things can cause premature
          erasure

<kevtris> There's no way to know when this effect will occur, and likely
          it will start out slowly, taking one or two cells out, then more as
          time goes on

<kevtris> if caught, it *may* be possible to "fix" the problems, but this
          is difficult, at best to do

<kevtris> I have seen bitrot first hand, so it is a real phenomena

<kevtris> there, good enough? :-)

<blackjax> like that power pad test cart

<kevtris> yes

<blackjax> heck,, that's perfect

<kevtris> also, I've seen it on some other things I've gotten

<kevtris> I had 5 identical "things"* and all 5 had EPROMs on them

<reio-ta> kev: then we better find the rest of these pc-10 chips that are
          out there somewhere. they are reaching the 20 year mark really soon

<kevtris> * = "things"... hard to describe.  It was a modem with 4 LED
          displays and a keypad, meant to enter stock quotations :-)

<kevtris> I noticed that 2 of them didn't work right; they would crash
          when I tried various things on them

<kevtris> so I pulled all 5 EPROMs eventually (to re-use them) and sure
          enough, those 2 had some bit-rot on the EPROMs

<kevtris> some of the bits had reverted to a non-programmed
          (erased) state... i.e. bits changed from 0 to 1, and there were 
          no 1 to 0 changes

<kevtris> 1 = erased, 0 = programmed

<kevtris> you cannot program a "1" if the cell has a 0 on it unless you
          erase the whole EPROM

<kevtris> I've also seen EPROMs actually damaged *inside* under the window
          twice

<kevtris> once was in a supercharger demo unit; the protection diode fell
          off and rattled around inside, which destroyed the bond wires

<blackjax> yikes

<kevtris> rendering the EPROM fucked

<blackjax> that's murphys law proven

<kevtris> I programmed a new EPROM (fortunately the EPROMs were dumped
          from another one) and it worked great after that :-)

<kevtris> the other was on one of dreamTR's carts

<reio-ta> kev: so this just shows that nintendo are correct about their
          speech that you would never need to make a backup of any of your chips.
          they last forever :>

<kevtris> bond wire fell off the die on the CHR ROM of that shadowgate
          proto

<kevtris> so D7 was missing and all the graphics had lines through them

<kevtris> fortunately, the proto was no different than the release version
          so I just burned another EPROM and that fixed that

<kevtris> reio: heh

<kevtris> NOTHING is forever

<reio-ta> but butttt... nintendo said it was :<

<kevtris> heh and nintendo can do no wrong, hunh?

<blackjax> so even with the sticker covering the window, and if it's
           handled with white cotton gloves, it could start degrading

<kevtris> bj: yes, because those pesky electrons will slowly leak off,
          'cause no insulation is perfect

<kevtris> using the EPROM causes slow degredation too, but we're talking
          10+ years of 24/7 use here, at over a million reads a second

<kevtris> casual playing of proto's will not impact the lifetime more than
          a couple minutes or seconds probably

<blackjax> however, some dumbass throwing uncovered eproms onto a scanner
           to brag about his find could cause some harm

<kevtris> naaah

<kevtris> flourescent light won't hurt them

<kevtris> shortwave UV is what erases them

<blackjax> the stuff that we can't see

<kevtris> flo's may hurt it but it'd take 2-5 years to erase it under
          continuous exposure

<kevtris> sunlight would take several weeks of full sun and no clouds

<kevtris> there really is no sub for a good eraser

<reio-ta> bj: so that means dont take your proto in with ya when you go
          into a suntan chamber

<kevtris> naah that won't work either

<kevtris> that's the wrong wavelength

<kevtris> that's UVa

<kevtris> you need UVb or shorter... germicidal lamps are usually the ones
          used

<reio-ta> are you sure? i had a teacher who is an electrical engineer. he
          said it would work

<kevtris> heh

<kevtris> I won't dignify that with a reply

<kevtris> you try to tan with a UVb source and all you get is burned and
          cataracts and other occular damage

-:- Newo is now known as NewoAway

<NewoAway> I am away. Reason: STOP. Burrito time.

<reio-ta> kev: then that would have been an even funnier story if he had
          actually tried going to a tanning salon to bring in his eproms
		  to erase and they didnt erase. he finally got ahold of an eraser
	      but he was tempted to goto a tanning salon

* blackjax saves text file

<reio-ta> kev: well the funniest story was how he was working on the
          controller using a 8051 to be used in a blender to run the
	      motor. it was breaking for many people in home use yet it passed in the
		  lab. they tested it making all sorts of stuff. they even made
		  margaritas in it. but they didnt use alcohol. that was the problem alcohol
          causes the ice to get even colder and when it reached that
		  really low temperature it caused the motor to quit f

<blackjax> thanks kev, now this should sound better

<kevtris> bj: np