Hi folks:
I recently got two Osborne 1 computers. The first one (blue case) had a
dead power supply -- I fed +5/+12 DC power into the battery connector and
was able to bring it to life, but had no software to test it further. This
one has a double-density option board inside (and drives I presume), as
well as the optional modem.
I also got a second osborne (early beige case), which came with software
and manuals. This one has a keyboard that seemed to have a stuck key.
Turns out that the keyboard matrix has many shorts, not only row-to-column,
but also row-to-row and col-to-col. It is a flex-circuit soft of design,
and it appears to have a silk-screened or deposited metallization pattern
for the matrix. There is an insulating layer of some sort and then a
second metal layer. Anyway, it seems that the insulation between layers
has failed where some traces cross. It'll be a mess to fix, if even
possible. Anyone else have this problem on an early keyboard?
So I plugged the later keyboard into the early unit, and was able to boot
cp/m. I tried to copy the original cp/m disk to a new one, but copy had
read errors on a couple of tracks. I could see some visibly-crappy spots
on the disk surface too, but it did boot fine, and the utils seemed to run
ok. So I formatted a new disk, copied just the system, and then pip'd the
files over. Hmm, no errors on file reads with pip -- does that make sense,
since copy previously found bad tracks? After booting and running off the
new disk, it seems that all command files are working, with the possible
exception of movcpm (which seems to hang the machine, though I am not sure
how it works).
So I finally got the original disks copied, and learned a bit about the
machine in the process.
I fired up the later (double-density) model, but it would not boot from the
single-density disk. Should the DD drive be able to read the SD disk? The
drive was making an odd noise, so it may be drive-related. Is there a way
to boot from drive B? Can I swap the drives, and if so are there
master/slave jumpers, or terminations that need to move as well? On the
early machine, there was a diagnostic mode in rom (ctrl-D at the boot
screen, I think it was), but the newer unit does not respond to that. Were
diagnostics removed from later roms?
I swapped the working power supply from the old unit into the new machine
(yes, I know about the different jumper/harness connections). It worked fine.
Then, I put the non-working power supply into the early unit, and it
started working! I think the original power supply problem in the newer
machine may have been an intermittant in the fuse/voltage-selector gizmo,
which tells the PS whether to expect 115 or 230 -- in the early unit, this
gets hard-coded by the jumper wire on the PS board. Crazy frickin'
computers.
Then I accidentally cracked the brightness trimpot on one, as I put things
back together. Tacked a temporary pot in place while I look for a
replacement. I shouldn't try to do this stuff at 2 in the morning, I guess.
Well, that was sort of an FYI ramble, but any thoughts appreciated. Does
anyone have double-sided software for sale or trade?
thanks,
gil smith
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Received on Tue Nov 19 2002 - 11:31:00 GMT