[SGVLUG] Ooooooooold computer

[Claude Felizardo]

Plug boards!  I remember seeing a plug board for a bunch of 555/6 timer
chips that was supposedly used to control the animation on the Cal Poly
Rose Parade Float but they had already moved on to a Rockwell Aim-65 by the
time I got there.  I also heard that they had tried to use bubble memory
cards but there was some kind of problem with them so they had to give them
back.

The other nifty thing was the use of a custom built 12-bit UART using
discrete chips -- 4 bit address followed by 8 bits of data, 2 bits per
channel so 01 meant move cylinder one way, 10 the other way and 00 and 11
were illegal.  That should be enough for 64 channels but I know they were
limited to only 32 channels when I got there.  Hmm.  Maybe there start/stop
bits?  Oh, the I/O panel could only control 32 valves with manual overrides
so it had a lot of toggle switches and LEDs.  Omni magazine shot a cool
picture of that panel one year as it looked like it belonged in a
spacecraft.  Let's see, there was a bank of power transistors that
controlled the 24 vdc manifolds - either hydraulic or pneumatic.  32 was
the limit for a while but one year they had a lot of animation so I was
able to resurrect an old 16 channel I/O card and modify the assembly code
so we had a whopping 48 channels that year.

The UART was in the I/O panel and the interface to the computer was a
fiber-optic cable so at Post Parade I would demonstrate that by pulling the
cable from the computer and all the computer controlled animation would
stop until the cable was reconnected.  That and letting people control the
animation via a joystick was a blast.

Wow, that triggered a brain dump...




On Thu, Apr 25, 2013 at 6:34 PM, Doug <dougvargas at sbcglobal.net> wrote:

> I'm sure many of you saw this on Slashdot today, but holy crap! Really
> gives new meaning to the phrase "if it ain't broke don't fix it"
>
> http://kottke.org/13/04/dont-mess-with-texass-old-computers
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