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by Bill Degnan - 06/14/2011 20:56 | |
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 in the back. The serial connector pins you need to connect to the teletype are 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. 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. Source - Paraphrase from IBM Technical Reference Manual volume 2 Reply |