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Browse Prior Art Database

Enhanced Mouse Mode for the Keyboard/Mouse Controller

IP.com Disclosure Number: IPCOM000099521D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 72K

Publishing Venue

IBM

Related People

Blackledge, JW: AUTHOR [+4]

Abstract

This article describes the establishment of address parts for the exclusive use by a mouse device in a personal computer system, instead of sharing ports with a keyboard device.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Enhanced Mouse Mode for the Keyboard/Mouse Controller

       This article describes the establishment of address parts
for the exclusive use by a mouse device in a personal computer
system, instead of sharing ports with a keyboard device.

      In existing personal computer systems machines the system
programmer does not have independent control over the mouse port.
The system programmer must use the keyboard data port addresses to
read, write, and monitor the mouse device.  This dual usage of the
keyboard data port exposes the system to data integrity problems and
forces the programmer to use additional steps to write to the mouse
device.

      Data integrity is jeopardized when the mouse controller is
enabled and receiving data from the mouse device.  Upon completion of
the data transfer from the mouse device to the mouse controller, an
interrupt is generated by the mouse controller.  If, before the
interrupt is acknowledged, the CPU requests the keyboard device to
resend the last data, the keyboard controller will write the data
received from the keyboard device into the port, and unintentionally
destroy the mouse data, which is also located in the port.

      To ensure data integrity, the system programmer must disable
the mouse device when the keyboard device is enabled.  Conversely,
the keyboard device must be disabled when the mouse device is
enabled.  This present approach increases system programming overhead
and decreases keyboard and mouse data throughput.

      With the exist...