MITS Teletype Interface Board

From: Dwight K. Elvey <>
Date: Thu Aug 5 21:28:31 2004

 It doesn't look like it has enough on it to be a
RS-232 converter but it could be a 20 to 60 mil
 You might look at the circuit layout around the
thansistors labeled Q1 to Q4. Tracing this part
out will most likely figure out what the intent
is. It looks like it does replace some of the power
supply sections of a ASR33 so that would explain the
look of a power supply.
 You can power the unit up and look at the voltages
on the DB25. I tend to agree that missing both
pin 1 and pin 7 would indicate that it wasn't a

>From: "Brian Knittel" <>
>For those of you who asked to see the MITS
>Teletype Interface board I mentioned a couple
>of days ago, I've put a picture at
>The molex connector at the bottom left below the relay
>is where the data cable connects. The other end is
>a DB25 connector, and the wires go to pins 2-6. Since
>there is no connection to pin 7 (signal ground) it must
>be current loop.
Received on Thu Aug 05 2004 - 21:28:31 BST

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