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Browse Prior Art Database

Method for Selecting More than Two Keyboards

IP.com Disclosure Number: IPCOM000113542D
Original Publication Date: 1994-Sep-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Inoue, A: AUTHOR [+4]

Abstract

Disclosed is a method for selecting one of the keyboards electrically in case that a personal computer has more than two keyboard connectors. This method can be implemented by virtue of electrical logic circuits and software codes called Basic Input Output System (BIOS).

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 87% of the total text.

Method for Selecting More than Two Keyboards

       Functional Diagram of Keyboard Switching Logic

      Disclosed is a method for selecting one of the keyboards
electrically in case that a personal computer has more than two
keyboard connectors.  This method can be implemented by virtue of
electrical logic circuits and software codes called Basic Input
Output System (BIOS).

      The Figure shows the sample of the functional diagram to select
one of two keyboard connectors.  CPU is a main processor of the
system unit that executes the software codes called BIOS.  Keyboard
Controller is a known controller in the field to control a keyboard.
Switch Control Logic Circuit consists of some electrical circuits to
generate a register which can be read and written from I/O
instructions of CPU and a signal which controls Selector Logic
Circuit.  Selector Logic Circuit consists of some electrical circuits
to connect signals between Keyboard controller and the selected
keyboard connector.  The following is a sample of the sequence to
select one of the two keyboard connectors.  When the system unit is
reset, the software codes control Switch Control Logic and select
Keyboard Connector-1 at first.  Then they issue the keyboard reset
command to Keyboard Connector-1 through Keyboard Controller, thereby
can be judged whether  a keyboard is attached to Keyboard Connector-1
by the acknowledge status.  Secondly they do the same manner for
Keyboard Connector-2.  Final...