[pups] PDP-11 / vacuum tube interface

robinb at ruffnready.co.uk robinb at ruffnready.co.uk
Wed Dec 10 19:21:37 AEST 2008

That's a wonderful idea.  As has been pointed out there are a number of A2D and D2A boards available for the PDP11.  However it would be fun to do it yourself and design one from scratch although getting hold of prototyping boards for unibus or Q bus could be a bit difficult these days.

You would probably have to down convert your RF to audio to keep everything in the realm of what the PDP could handle though something like PSK should be able to be resolved, morse should be a doddle.

Have a go, this is seriously pointless geeky stuff and as a result huge fun.


rjtucke at gmail.com wrote:
> 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
> challenge.
> 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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