TTY 33 - Finally - UPDATE

william degnan billdegnan at
Sat Jul 4 14:32:07 CDT 2015

Here are some photos or the original board

I have found with DEC computers you don't need the relay to simply load in
a tape, such as BASIC into memory.


On Sat, Jul 4, 2015 at 12:02 PM, tony duell <ard at> wrote:

> >
> > Now to see if I can find out how to make a facsimile of the tape reader
> control gizmo that DEC
> > used to allow the PDP 8 to control the paper tape reader, so I can get
> this terminal properly
> >  interfaced to the 8/e.   In the meantime, I'm going to hook it up to
> the Altair 8800 for a little
> > immediate nostalgia.
> Various companies had their own version of the reader control board, but
> they were all much the same in
> principle. A relay with contacts in series with the reader control circuit
> (the one that operates the trip coil
> at the back of the typing unit. The important thing is that it is a relay.
> In most cases that reader control
> circuit is not isolated from the mains power line. The relay, of course,
> provides isolation between the
> computer (coil) side and the contacts.
> If you are tempted to use some more electronic solution you must preserve
> this isolation ,for example by
> using an optoisolator. You do not want to give you and your 8/e a nasty
> shock.
> -tony

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