Re: What Tektronix means to me

Harvey White

Heh, well, not that I know about lazy.....

74181 and 7489's.  Timing generated by a counter that gave 8 decoded time states per instruction, fetch, operate, adjust, etc.

I actually bought stuff from Digikey (think it was the same) before they went honest and started carrying new stuff.  This was when they were giving polypacks a run for their money.

I knew video, I liked video, so I had a video display, color, with a user definable character set for the top 128 characters. Color, too.

I discovered the 2901 bit slice stuff, and thought it quite complicated.  Somewhere around 1989 or so I ended up translating a 2901 bitslice design (was working from flowcharts and only did the software) from that to a 29116/29117 integrated bitslice design, much nicer model.  That was a retrofit for the ARSR3 airport approach radar as part of the 3 level weather upgrade.  (to be specific, it was in the correlator and formatter... all assembly of the "roll your own" variety).  Never did any bit slice until then.

The first scope I had was a heathkit OM-3.

Then the Tektronix 513D and 512.

Then the next I got was the telequipment D75.

Somewhere in there I built a scope with a 3 inch surplus tube from a schematic I got from the heathkit catalog.  Remember when they had tiny little schematics in their catalogs?   Magnifying glasses can be your friends.  Built it on a breadpan for a chassis.

Went to a Kenwood, 4 channel analog with readouts, then a 2430A, and thence into 7000 series, starting with the 7704A.

Went into logic analyzers...

Started with an HP1630D, then 1650, then 1661, then 16500B, and finally ended up with a 16702A, then went to the 16702B.

All I have left (that I want to give new homes) are the 16500B and the 16702A's.  The 16702B is the mainstay of the logic analyzers.

Somewhere in there I got a 1640 serial analyzer (needs new home, I think).  a Tek 308 (cute, but not too useful), and an HP serial analyzer (which I'll keep).

More fun.

The 7904/16702B are the mainstays of the development cycle, adding in a TDS540A for more digital.


On 1/21/2020 11:07 AM, Chuck Harris wrote:
I said I was greedy... It didn't serve my purposes to also
mention that I was lazy.

I thought it wasteful to use ripple carry on the S181's, so
I included the S182's with their carry look ahead, or whatever
it was called.

I used 7489's for my register file. I don't recall my plans
for RAM, or disk storage... I think I was waiting for divine
inspiration... I did have a pile of and 1103's on hand.

My design was front panel, and TTY console only. None of this
video stuff. This was 1974 or 5... And my available TTY was
an old baudot Model 15 tty.

I would have used ECL, but it was available only in simple
functions... and not at hamfests.

At some point, I discovered the 2901 bit slice ALU's, and
school got too busy to continue this nonsense.

I found my cache of pencil drawings (on the backs of green
bar line printer paper) two dozen years ago, shook my head,
and dumped them into the trash bin.

Some years after my fixing my 513D, I found one for $5 with
a smashed up CRT. I swapped out the repaired vertical attenuator
switch, and replaced my side fan with the rear fan and filter
from the newer 513D, along with the case. I probably shouldn't
have done that, as it ruins the authenticity of the scope... but
then, so did all my repairs. I am sure that a real 513D never
had all of those yellow CDE mylar caps, and a red oil filled glass
cased unblanking capacitor.

Some day we all will have to talk about the differences between
the old Vollum designed scopes, and the later plugin scopes.

Clearly someone far more cleaver took over the task. The
circuitry went from brute force designs that used the hell out
of the tubes, to inspirational designs, that cherished the tubes...

I wonder who that was? (Calling: Dennis Tillman.)

My second scope, after the 513D, was a plain Jane 545. I had the
scope for only a couple of days before I learned that what I had
really wanted was a 545A, or 545B... All of the interesting
combinations of the dual timebases were left off of the 545...
relying instead on the user connecting cabling between vertical
outputs, gate signals, and the external trigger inputs... bah!

My third scope was a brand new 2465.

It all gets fuzzy after that.

-Chuck Harris

Harvey White wrote:
Hah.  I think you underachieved on your design <grin>.

I have to remember back more time than I care to remember, but the ALU for the jump
computer was 74181's, and I think that the FPU CPU was 74181's, but 4 of them.  I had
hardware multiply, since I didn't know microcode, nor did I have a memory chip (this
was before even 1702's)  I may have had 7489's as memory, and the arithmetic was
BCD.  Don't quite remember how I did that, but I did.  The address computation was a
separate processor and did some odd things to get the addressing done.  Memory was
2102 1K x 1 static memory (two voltages) which were also part of the video display
controller.  It had its own NTSC driver (a separate NTSC sync generator with a
dot/bar/crosshatch generator, also had R-Y and B-Y encoders. (IVC Camera schematic,
homemade PC boards), and that drove the display.  Since the CPU was sharing the video
display memory, you had a bit of an idea what was going on.

Very old design.....

The next scope I got was a Telequipment D75 when Tektronix was closing them out, many
years later and when I actually had a bit of money.  It had its own share of


Join to automatically receive all group messages.