A tale of two Osbornes

From: Sark <ian_primus_at_yahoo.com>
Date: Tue Nov 19 17:48:27 2002

Well, at least you were able to get it running. I have a later model
Osborne 1 that I can't get to work. It worked fine for a half hour or
so, then the screen went out. If I crank up the brightness all the way,
i get the rasters on the screen, so the tube is getting power, and the
computer will attempt to boot, and read from the drive. Everything
seems fine except for the fact that there is no video... I tried
reseating chips, but I think I have a bad logic board. No way to test
though.

Ian Primus
ian_primus_at_yahoo.com

On Tuesday, November 19, 2002, at 12:37 PM, gil smith wrote:

> 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
>
>
>
>
>
>
>
> ;-----------------------------------------------------------
> ; vaux electronics, inc. 480-354-5556
> ; http://www.vauxelectronics.com (fax: 480-354-5558)
> ;-----------------------------------------------------------
>
Received on Tue Nov 19 2002 - 17:48:27 GMT

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