Joel Kolstad wrote:
"Tom Bruhns" wrote in message
oups.com...
Some later scopes also came
with very accurate time measurement capability, and with features like
delayed sweep that would let you superimpose two sections of the trace
and read out the delay time directly.

Speaking of fancy old-school oscilloscope features... the old Tek analog
scopes (e.g., 2465) that actually had *on-screen text read-out* of
measurements such as time, frequency, etc... weren't those things designed
back in the '70s and early '80s? And as such didn't they probably need some
paper sheet-sized board full of tons of digital logic DIP ICs, PROMs, some
CPU, etc. to pull off such a task? And did they add a dedicated electron gun
for writing the text, or just update it inbetween sweeps? Mighty
impressive...

Actually by the time of the 2465 (which I personally regard as a "new"
scope) good chunks of the functionality were handled by
microprocessors. Yeah, there are PROM's and a CPU and NVRAM etc. More
notably there are a couple of custom Tek chips.

What I think is impressive are the early-70's-vintage Tek plug-in
mainframes where there was no CPU but they did have on-screen readout.
There's a "bus" of sorts in the mainframe that modules can use to
communicate (via mostly analog levels and time-based multiplexing)
results (not just numeric values but very importantly scale) to the
character generator (made of a mix of standard analog+logic and custom
Tektronix analog-digital stuff) that puts them on-screen. These have
two distinct modes, one where the character writing interrupts normal
operation of the scope, and another where the character writing occurs
in the refractory period between sweeps.

The character generation/selection logic is filled with substantial
amounts of cleverness (a lot of it embedded in the Tek chips but the
time-division bus is really very clever in terms of compactness and
implementability) so that it does not fill sheet-sized PC boards but is
in fact rather compact.

For the ultimate in character-generation cleverness, witness the Tek
4010 and 4014 serial terminals, which use storage scope technology
every way you could ever imagine. They pioneered affordable computer
graphics terminals way before anyone else (there were some
stratospherically priced ones from other outfits). One gotcha: the
RC-controlled baud rate generator!

Tim.