[GreenKeys] TTY 33 & IBM 5150

[billdeg at aol.com]

John,
I hope you don't mind that I post to the entire group, should someone else want this info too...

There is a socketed shunt module on the bottom right of the original IBM async board, just pull it out and re-insert upside down (so the dot is pointing down) for current loop.  If you're going to use slot 8 of an IBM PC or XT a jumper is required on connector J13.  Why, I don't know off-hand.


Plug a regular old EIA connector into the serial card.  The serial connector pins you need are:

pin 9 = + transmit current loop data
pin 11 = - transmit current loop data

pin 18 = + receive current loop data
pin 25 = - receive current loop data

[pin 25 is the bottom right (bottom = row of 12 pins)]

Then connect to ASR 33:

Transmitted data return (-) attaches to terminal strip screw 6 or "number 2 connector" #7 

Received data return (-) attaches to terminal strip screw 3 or num 2 connector #5 

Transmitted data send (+): Terminal Strip 7, #2 connector 8 

received data send (+): Term strip 4, #2 connector #6. 

If the tty stops chattering you at least have a current loop.  I have never done this before, let me know how it goes!  Oh and you'll need some sort of terminal program just like you'd use with an RS232 terminal connection, but you will need to use 110b, etc.

Paraphrased Source: IBM Technical Reference Vol. 2.

Bill



-----Original Message-----
From: John Whitney <john at johnwhitney.com>
To: billdeg at aol.com
Sent: Tue, Jun 14, 2011 2:13 pm
Subject: TTY 33 & IBM 5150


I have an IBM 5150 and a TTY 33 (20mA).

Can you point to info on how to hook them up per your greenkeys post?

I'd enjoy doing this if I could.

John Whitney
john at johnwhitney.com
801 815 9265