IMSAI 8080 - test-drb@ccmp.vtda.org

23 Jun 1998

...
 >> Yes, I wonder how many of these
'collectable' computers 
>> are in any sense being preserved properly. I would doubt 
>> if ROMs were ever backed up or PSUs tested.
> Hmm, IMSAI's didn't have ROMs (or PALs and FPGAs, programmable logic had

...
  The topic has drifted somewhat from the subject line -
I wasn't only 
 refering to IMSAIs, but also to LISAs, etc, which most certainly do 
 contain ROMs. 
:) And also the most IMSAI I'v seen (on other boards - just
to get power up a bit more comfortable :) 

...
  And anyway, a number of S100 cards included boot ROMs,
etc. Those need to 
 be backed up. 
Shure, but where ? Just on a disk ? I already have the problem
that I can't read some fd's of the early 80s. Even APPLE II disks,
althrough I always said that a DISK ][ drive could read and write
anything including Bierdeckl (beer mats/coasters).

So, what to use ? Writable CDs ? They have only a guaranteed
lifetime of less than 15 years. Tapes ? Maybe - I have some
PBS Tapes from 1976 and they are still readable, but they are
900 and 1600 BpI tapes. Any modern optical and magnetical
medium is less reliable. So printing the hex dump and then
try to scan it back (ocr) when a replacement is needed ?
This sould be reliable, since it is human readable (Like
old magnetic tapes).

Or just put it again on EPROMS - with propper handling
EPROMS could survive at least 50+ years - and PROMS
(real one not EPROMS without window) should live even
longer. So just copy them. And beside the information -
it will be even more dificult to get a usable 2704 or
2708 not already needed for an old computer.

...
 > yet to be invented), unless you added them in
yourself.  As for checking
> the power supply, an IMSAI was extremely easy to eyeball...huge
> transformer, diodes, and beer can size capacitors.  One problem I never 
...
  Yes, but there are regulators on each S100 card. If
you've got a card 
 with rare socketed chips on it, I'd pull the chips and power up the card 
 without them the first time. Then check the local +5V rail, etc. It only 
 takes a dry joint on the ground pin of a 7805 ( or worse still, loose 
 screws on the TO3 canned version) to wipe out the entire board of IC's. 
...
  If you think I'm paranoid about this, I am.
I've had it happen, you see, 
 and I don't want it to happen again. 
I hope you keep this attitude for the next 20 years.

Gruss
H.

--
Ich denke, also bin ich, also gut
HRK