Input/Output Interfaces

 

 

 

 

 

 

 

 

 

 

 

 

Table 5-13. (Continued)

 

 

 

 

8042-To-Keyboard Commands

 

 

 

 

 

 

 

Command

Value

Description

 

 

 

 

 

 

 

 

 

Set Keys—Make/Brake

F8h

Clears keyboard buffer

and sets default scan code set. [1]

 

 

 

 

 

 

 

Set Keys—Make

F9h

Clears keyboard buffer

and sets default scan code set. [1]

 

 

 

 

 

 

 

Set Keys—

FAh

Clears keyboard buffer

and sets default scan code set. [1]

 

Typematic/Make/Brake

 

 

 

 

 

 

 

 

 

 

Set Type Key—Typematic

FBh

Clears keyboard buffer and prepares to receive key ID. [1]

 

 

 

 

 

 

Set Type Key—Make/Brake

FCh

Clears keyboard buffer and prepares to receive key ID. [1]

 

 

 

 

 

 

Set Type Key—Make

FDh

Clears keyboard buffer and prepares to receive key ID. [1]

 

 

 

 

 

 

Resend

FEh

8042 detected error in keyboard transmission.

 

 

 

 

 

 

Reset

FFh

Resets program, runs keyboard BAT, defaults to Mode 2.

Note: [1] Used in Mode 3 only.

5.6.2 Pointing Device Interface Operation

The pointing device (typically a mouse) connects to a 6-pin DIN-type connector that is identical to the keyboard connector both physically and electrically. The operation of the interface (clock and data signal control) is the same as for the keyboard. The pointing device interface uses the IRQ12 interrupt.

5.6.3 Keyboard/Pointing Device Interface Programming

Programming the keyboard interface consists of configuration, which occurs during POST, and control, which occurs during runtime.

8042 Configuration

The keyboard/pointing device interface must be enabled and configured for a particular speed before it can be used. Enabling and speed parameters of the 8042 logic are affected through the PnP configuration registers of the SCH5317 I/O controller. Enabling and speed control are automatically set by the BIOS during POST but can also be accomplished with the Setup utility and other software.

 

Technical Reference Guide

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