Latest Acquisition: Imlac PDS-1D

From: Don Maslin <donm_at_cts.com>
Date: Tue Apr 10 17:51:39 2001

On Tue, 10 Apr 2001, Tom Uban wrote:

> Sellam,
>
> Nice! I haven't seen this particular model before, but it has many
> similarities with the PDS-1.
>
> >The CRT is obviously going to need replacing. It looks like I may be able
> >to just remove the front glass panel and then chip off the intermediate
> >glass (plastic?) layer that is all cracked to reveal a clean tube on the
> >inside, but I don't know if this is just an optical illusion (and I don't
> >know if this would be safe :) The tube has a Fairchild sticker on it.
> >Apparently Fairchild made CRTs in the late 60s, early 70s. I wonder if I
> >can just find a replacement?
>
> All of my Imlac displays have some amount of this disease, but not nearly
> as bad as the one in your picture. I am planning on trying a test on one
> of mine if I cannot find a replacement tube. The test constists of building
> an enclosure with a pan in the bottom in which I can soak the face of the
> tube in acetone in order to disolve the resin which is between the face of
> the actual tube and the plastic protection layer. If the two can be
> separated in this way, then the plastic can be re-attached to the tube
> with a new layer of resin. This design is similar to the process used to
> hold camera lenses together as they are often made up of multiple layers
> of glass. I have a friend who repairs antique cameras and he suggested this
> approach. As someone else noted, it would not be safe to operate the tube
> with out the protective layer, but I hope that with careful handling, it
> can be repaired back to new condition.

It may work, but I'd guess it will take an eternity to dissolve the
resin. Remember, you have a lot of area to dissolve and are getting at
it on an edge that is likely only a few thousandths thick. Also, keep
it well away from any source of combustion. Acetone is rather combustible
and the vapor could be explosive.

                                                 - don
 
> >The nice thing about this one is that it came with the programmer's
> >console. And if you'll look at the picture showing the front card cage
> >with the logic modules, the long board in the lower right is a "Long
> >Vector Option", hand-wired by the guy I got it from. It's basically a
> >co-processor board for drawing the vectors on the display. It allowed the
> >system to handle more vectors than the basic configuration. Apparently,
> >if you had too much happening on the display the system would bog down
> >considerably or crash.
>
> The console in your picture is also different than that of the PDS-1. You
> have a wood enclosure and mine has what I think is a fibreglass enclosure.
> More importantly you have a knob and mine has some discrete switches.
>
> >The display for the PDS-1D is very different from the PDS-1. It's much
> >larger and has a detached keyboard. The computer itself is also very
> >different. The card rack uses different connectors, and the memory is on
> >the other side of the rack instead of plugged into the card cage along
> >with the rest of the logic modules, as with the PDS-1.
>
> The keyboard on my PDS-1 is detached, but is molded/styled to match the
> display enclosure. Interesting on the memory. Of the different models
> I have seen, the memory does seem to move around a lot from design to
> design.
>
> >From talking to the previous owner, I'd hoped I would be able to just
> bring it home and fire it up after some TLC with a Variac, but that ain't
> gonna happen. He never told me he'd stored it outside. Duh. But I think
> with a bit of work it can be made to function in time for VCF 5.0, in
> which I hope to include it in an exhibit of early networked video games.
>
> It would be great if you get the machine up and running for VCF 5.0! I
> have been considering bringing my this year as well, so if we both do,
> perhaps we can "network" them...
>
> >One cool aspect of this machine is that it has a diode ROM board that
> >instructs the machine to boot off the serial port. The previous owner
> >wrote some code for his Cromemco that would upload operating software
> >into the Imlac. He also wrote an assembler on the Cromemco so that he
> >could assemble programs and then upload them to the Imlac. Pretty
> >cool.
>
> I think this was normal for most of these (to load from the serial port).
> I did see a unit which had an Iomega (RK05 like) removable hard drive with
> it at one time. Sadly, the drive was discarded over the years.
>
> >This will be my main restoration project for the time being.
>
> Do you have the prints that you need. I have prints for all of my machines,
> but they may be different enough that they would not help you. Let me know
> if I can be of any assistance.
>
> Your pictures have inspired me to put up a better set of images on my site.
> I will try and do that tomorrow...
>
> --tom
>
>
Received on Tue Apr 10 2001 - 17:51:39 BST