Q68110: I/O Addresses for the Microsoft Mouse

Article: Q68110
Product(s): See article
Version(s): 1.00
Operating System(s): MS-DOS
Keyword(s): ENDUSER | | mspl13_basic
Last Modified: 10-FEB-1991

The following are the ranges in which an I/O (Input/Output) port
assignment may occur for the Microsoft Mouse. The ranges are given in
hexadecimal numbers, and the serial communications port assignments
conform to the IBM standard I/O address range assignments for PCs and
PS/2s.

SERIAL MOUSE
------------

Port Assignments    Address Ranges
----------------    --------------

COM1                3F8H-3FFH

COM2                2F8H-2FFH

BUS MOUSE (BUS INTERFACE BOARD SETTINGS)
----------------------------------------

Primary Inport Range
--------------------

23CH-23FH

Secondary Inport Range
----------------------

238H-23BH

An I/O port acts as a doorway through which information travels.
Information may originate from the CPU, travel over data and address
buses, pass through the I/O port, and finally reach a peripheral
device such as the mouse. Although the CPU recognizes various ports
through 16-bit port numbers that range from 00H through FFFFH, the
port address is not actually an address found in main memory. A port
assignment is a memory location separate from a (main) memory address
that is associated with that particular I/O port.

No other peripheral device, such as a modem or printer, may share the
same I/O address with the mouse or the mouse may not function
correctly.

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