[pups] PDP-11 / vacuum tube interface

Ross Tucker rjtucke at gmail.com
Wed Dec 10 10:00:32 AEST 2008

Dear all,
(This has got to be the strangest cross-post I've ever done.)

I have just taken a bet from a friend to challenge my geekiness. I was
telling him about my love of Vintage Technology and he proposed that I
combine two hitherto separate hobbies and see what happens. The
topics: the DEC PDP-11 minicomputer (vintage: 1970s) and vacuum-tube
ham radios (vintage: 1960s). I do sincerely apologize for
cross-posting, but I am rather younger than either of these
technologies (vintage: 1984) and this seems like a monumental

My question for y'all: how could I possibly design+build a project
that uses both of these technologies? My thought is to port some radio
receiver Digital Signal Processing (DSP) application into PDP-11
assembler, compile and run it via emulator on my PC, then use it with
the vacuum-tube regenerative receiver that I built a few years ago...
Does anybody know if PDP-11 UNIXes even had the capability for a
"sound card"? Or, to get ambitious, I would LOVE to design some
interface circuitry between PDP-11 digital circuitry and vacuum-tube
electronics... The challenges are legion: the tube side of the circuit
operates around 350V DC levels with radio-frequency (RF) signals at 7
MHz (almost the clock rate of some PDP-11s!) and I don't have the DEC
Handbooks, but I'm pretty sure that even those ancient pre-TTL
circuits operate below 350V!

So... any, er, "ideas"?

Best regards,
Ross Tucker

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