Browse Prior Art Database

Keyboard Port Attachment

IP.com Disclosure Number: IPCOM000059640D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Heimsoth, AJ: AUTHOR [+3]

Abstract

This article describes a keyboard port attachment which provides a low cost interface to a personal computer (PC) for low speed serial input devices without using a card slot or attachment card. The keyboard port attachment described herein allows a user to interface certain devices to the IBM PC without using a card slot or an attachment card. The keyboard port attachment is a serial bidirectional four-wire interface which may be adapted for use by a low-speed serial device. The interface also includes a +5 volt power line which powers the serial device. The PC keyboard may coexist with the serial device on the port, although data transfers are non-concurrent. The keyboard port attachment is illustrated in the drawing.

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Keyboard Port Attachment

This article describes a keyboard port attachment which provides a low cost interface to a personal computer (PC) for low speed serial input devices without using a card slot or attachment card. The keyboard port attachment described herein allows a user to interface certain devices to the IBM PC without using a card slot or an attachment card. The keyboard port attachment is a serial bidirectional four-wire interface which may be adapted for use by a low-speed serial device. The interface also includes a +5 volt power line which powers the serial device. The PC keyboard may coexist with the serial device on the port, although data transfers are non-concurrent. The keyboard port attachment is illustrated in the drawing. It consists of a keyboard port plug 2 with a small circuit card 3, a jack 4 for the keyboard plug and a serial device interface cable 5 for the serial device. User installation of the serial device requires only plugging the keyboard port attachment plug into the keyboard port and re-plugging the keyboard into the jack provided on the attachment. The serial device attachment initializes the keyboard enable true for normal operation and power-up. When the serial device attachment requires use of the port, the clock line is monitored for a "not busy" high condition. The keyboard enable is made not true until the serial device has completed the transaction and then made true again. The transmitted scan codes may match the key...