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Serial-To-Parallel Interface Adapter

IP.com Disclosure Number: IPCOM000039273D
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 3 page(s) / 87K

Publishing Venue

IBM

Related People

Hutchings, JH: AUTHOR [+2]

Abstract

This article relates generally to computer interconnections and, more particularly, to an adapter for enabling interconnection of computers with serial and parallel data interfaces. (Image Omitted) A keyboard of an IBM Personal Computer having a serial data, interrupt-driven interface can be connected through an adapter circuit with a computer having a parallel data, polled interface. An example of an adapter circuit for interconnecting serial and parallel data interfaces is shown in the figure. The keyboard of the IBM Personal Computer requires Key Clock and Keyboard Data lines as input/output lines, a Keyboard Reset line as an input line, a positive supply voltage, and ground. The parallel interface requires eight data input lines, positive supply voltage and ground.

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Serial-To-Parallel Interface Adapter

This article relates generally to computer interconnections and, more particularly, to an adapter for enabling interconnection of computers with serial and parallel data interfaces.

(Image Omitted)

A keyboard of an IBM Personal Computer having a serial data, interrupt-driven interface can be connected through an adapter circuit with a computer having a parallel data, polled interface. An example of an adapter circuit for interconnecting serial and parallel data interfaces is shown in the figure. The keyboard of the IBM Personal Computer requires Key Clock and Keyboard Data lines as input/output lines, a Keyboard Reset line as an input line, a positive supply voltage, and ground. The parallel interface requires eight data input lines, positive supply voltage and ground.

Input lines of the parallel unit are sampled every two milliseconds for scan code of the depressed key and, if no key is depressed, an idle key value must be present. When power is applied to the serial keyboard, a -Keyboard Reset is provided. A Keyboard Clock is then applied to active internal diagnostics checking, and the value of x'AA' indicates successful completion. Upon a key depression, the scan code is passed over the

(Image Omitted)

serial

Keyboard Data line which is held low until the attached parallel system is ready for the next character. In Fig. 1, switch SW1 provides the keyboard and adapter circuit with the reset signal, switch SW2 initiates internal checking of the keyboard, switch SW3 blanks the displays, and switch SW4 permits showing either a constant or the last key depressed. The operational sequence of the circuit of Fig. 1 is illustrated by the timing diagram of Fig. 2 and is as follows:

1. Keyboard data deserialization is complete and

+Interrupt occurs.

2. Keyboard Data...