Microsoft KB Archive/68110

= I/O Addresses for the Microsoft Mouse =

Article ID: 68110

Article Last Modified on 11/16/2006

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APPLIES TO


 * Microsoft Mouse

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This article was previously published under Q68110



SUMMARY
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. This information applies to the Microsoft Mouse for MS-DOS systems.

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



MORE INFORMATION
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.

Keywords: KB68110

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