I was bored, and ported my version of SimH (which is an older
version, but with some stuff ripped out, and other stuff put
in) to my operating system for my ARM-based MCU board. It
now "acts" like a regular 11/83 when turned on, and will
happily boot Ultrix-11 off the CF card :)
Not as fast as running on a peecee, not half as much fun as
running a real '11, but hey, it DOES fit into my backpack.
From: pups-bounces(a)minnie.tuhs.org [mailto:firstname.lastname@example.org] On Behalf Of Jochen Kunz
Sent: Thursday, December 11, 2008 6:15 PM
Subject: Re: [pups] PDP-11 / vacuum tube interface
On Wed, 10 Dec 2008 19:09:34 +0100
"Fred N. van Kempen" <fred.van.kempen(a)microwalt.nl> wrote:
> smiling @ his nano-11 system running Ultrix, all the size of
> a matchbox..
nano-11? Please elaborate.
PUPS mailing list
> (This has got to be the strangest cross-post I've ever done.)
You've got that right :P
> 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
Well, several projects can be thought off in this scenario, but
if you want to keep it mildly useful, try to do something with
audio tubes connected to an '11 (OK, here's a spoiler: "you'll
make a PDP11-driven music player using a tube-based audio
backend"), or such. You could go into analog computing as
well, but that can be kinda hairy.
This more or less only requires building a usable D/A converter
on the '11, which then interfaces to the tubes. I'd use a DMA-
based 16-bit DA controller.
Fred (smiling @ his nano-11 system running Ultrix, all the size of
Back in the 1970's Paul Pierce used a D/A converter on a PDP-11 at the UW
Computer Systems Lab to generate music much like early PC sound cards did
-- by combining harmonics in various ratios. Although he happened to have
used RT-11, there is no reason why it could not be done under Unix. (The
UW Computer Systems Lab also had a Votrax).
So, sure, you could, with an A/D and D/A converter do something like
that. I am not sure that the various emulators have done emulation for A/D
or D/A, but in principle, it ought to be possible.
AC coupling (via a capacitor) of the input or output would remove any
concerns about the relatively high DC voltages. Besides, input signals
ordinarily come into the grids of vacuum tube circuits by way of a
transformer. Ditto for outputs from tube circuits.
At 05:37 PM 12/9/2008 -0800, Carl Lowenstein wrote:
>On Tue, Dec 9, 2008 at 4:00 PM, Ross Tucker <rjtucke(a)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"?
>Well, you could look at "Votrax" on Wikipedia. Allegedly, the first
>words spoken by a Unix system at Bell Labs, using its Votrax
>synthesizer, were "file not found".
>Things that are now known as "sound cards" were called A:D and D:A
>converters back in those days. And there were a fair variety of them
>available for both Unibus and Qbus systems.
> > 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!
>The vacuum-tube circuits may be running from 350 VDC but somewhere
>there are low-level inputs from which everything is amplified. Think
> carl lowenstein marine physical lab u.c. san diego
>PUPS mailing list
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