Browse Prior Art Database

Interface of PC/XT to Tektronix 3270

IP.com Disclosure Number: IPCOM000036410D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 119K

Publishing Venue

IBM

Related People

Wikiera, PS: AUTHOR

Abstract

A useful modification of the IBM asynchronous communications card is described. The modification allows the IBM PC/XT to interface with the existing asynchronous line interface card (DL11-0) in the DEC PDP 11/34 computer. The computer in turn may drive a Tektronix 3270 tester. Previously, only Tektronix terminals could be used with the Tektronix 3270/DEC PDP combination.

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Interface of PC/XT to Tektronix 3270

A useful modification of the IBM asynchronous communications card is described. The modification allows the IBM PC/XT to interface with the existing asynchronous line interface card (DL11-0) in the DEC PDP 11/34 computer. The computer in turn may drive a Tektronix 3270 tester. Previously, only Tektronix terminals could be used with the Tektronix 3270/DEC PDP combination.

Shown in Fig. 1 is a schematic of the IBM asynchronous card. Fig. 2 depicts the modifications made to the card to allow the interface with the PDP computer. The modifications include the addition of a three-pole double-throw (3PDT) switch S1. The land between pin 10 in the 8250 universal asynchronous receiver-transmitter (UART) U11 and jack 8 in jumper block U5 is cut to permit insertion of the 3PDT switch S1. Additional wiring is also added.

These modifications allow pins 3 and 6 on dual line driver U13, pins 12 and 13 on hex inverter buffer/drive U8 and pin 14 on resistor pack R1 to be utilized, which were previously unused on the card.

(Image Omitted)

The previous Tektronix terminals supplied a band rate clock pulse to the DEC asynchronous line interface card (DL11-0). This signal is not typically provided by the IBM asynchronous communication card, but through these modifications is taken from pin 15 on 25-pin D-shell connector P1. Also required was a signal inversion of the received data. This was accomplished by using the unused hex inverter U8.

By turni...