GACK! (Excuse me.) Hello!
That description of how someone back there used a batch of LEDs and
photodiodes to form an input device triggered a memory of my own. One
Steve Ciarcia who wrote the Circuit Cellar column for Byte magazine
described that same method. He even included a photo of the prototype
using a picture frame to hold them. The code to manage it was written
in BASIC of all things for one of his custom cards, and it was mounted
on his equally custom system. He also described a similar method of
generating graphics using two DAC devices and a scope itself switched
into X-Y mode. (Code was also in BASIC for starters.)
Let us now return to the wonders of UNIX and as it relates to the
early networking ideas.
Gregg C Levine gregg.drwho8(a)gmail.com
"This signature fought the Time Wars, time and again."
On Thu, Jan 23, 2020 at 9:38 PM Jon Steinhart <jon(a)fourwinds.com> wrote:
Paul Ruizendaal writes:
Memory lane has a lot of potholes. This was a really long time ago.
Many thanks for that post - really interesting!
I had to look up "Pierce Network", and found it described in the Bell Journal:
In my reading the Spider network is a type of Pierce network.
However, the network that you remember is indeed most likely different from Spider:
- it was coax based, whereas the Spider line was a twisted pair
- there was more than one, whereas Spider only ever had one (operational) loop
Condon and Weller are acknowledged in the report about Spider as having done
many of its hardware details. The report discusses learnings from the project
and having to tune repeaters is not among them (but another operational issue
with its 'line access modules’ is discussed).
All in all, maybe these coax loops were pre-cursors to the Spider network,
without a switch on the loop (“C” nodes in the Pierce paper). It makes sense
to first try out the electrical and line data protocol before starting work
on higher level functions.
I have no idea what a GLANCE G is...
Again, very fuzzy memory here but there are a few folks on the list who might
remember more like Heinz. As I said earlier, I recall Sandy being in our group
so our network may have been the first try. I don't know who designed it.
The GLANCE G was an experimental graphics terminal developed in our group. I
think that John Camlet did a bunch of the hardware design as I have a strong
memory of a long afternoon with him after having weird squiggles show up in
short vectors which turned out to be a microcode bug. The thing had 4K
resolution in at least one axis, it may have been a square screen. It used
1K DRAMs and was built around a 74S181 bit slice machine. A lot of interesting
stuff was done on it; I mentioned Dick Hause's Display Terminal Editor in an
earlier post. I also remember a really nice graphical demo of how the phone
network routed around outages which of course no longer works due to lack of
Oh, yeah, the real use for these comes back to me :-) A number of the folks
in the group including Carl Christensen (who was one of the two people who
interviewed Ken for his job at the labs) had purchased property up in
Vermont for ski cabins. These lots had ancient surveys, the old "from the big
tree near the large rock" sort of property descriptions. So the main use of
the Glance G's for a while was to draw out the surveys and figure out what to
do about closure errors. If you don't know about it, and this is the only
reason why I do, a closure error is when you follow the property boundary
described by the survey and the end isn't at the beginning.
Anyway, these were very cool machines for their time. I don't recall any other
graphical devices at the time except for glass tty terminals, Tektronix storage
tubes, and the GRIN-2 on the PDP-15 that we used for space war as per earlier
Dave Hagelbarger designed the keyboard and to this date it's still one of the
best keyboards that I ever used as far as feel goes. It had plastic cups under
the keys that gave resistance and then accelerated after a certain point so you
pushed on a key and then it would shoot the rest of the way. And there was a
solenoid on the bottom of the circuit board so there was a little click that
you felt in your fingers. Great feedback.
There were some extra parts left over from building these. I remember that Joe
Condon had the glass shop do some work on an extra or dead CRT, and one of the
terminals in his office was actually a fish tank. When you turned it on a light
would come on behind the tube and you could see the fish swimming around in it.
Maybe Joe deserves credit for the original fish screen saver.
Oh yeah, another thing that I remember being tried was that someone had built an
array of LEDs and photodiodes surrounding the screen that could be used as an
input device. It was low res but you could point at things with your fingers.
One of the projects that I did was to write software for nicely plotting graphs
on these. Was used a bunch by Jim Kaiser and crowd for their digital filter
work. I remember a really nice graph that Jim did that showed just how carefully
the touch tone frequencies were chosen to have no harmonics in common.
This isn't really UNIX stuff but I suppose that it passes for prehistory. Again,
I seem to recall that one of these was up in the UNIX lab but have no memory of
what it was used for. If I had to guess, it would be chess.
Oh yeah, I think that you can see the GLANCE G instruction set if you have a
first edition copy of Newman and Sproul. I remember getting a copy of that book
and having a weird sense of deja vu during their discussion of vector graphics.
Then I realized that it was because it was the instruction set that was burned
into my memory.