5-20 www.hp.com Technical Reference Guide
Input/Output Interfaces
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 SCH5307 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.
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—
Typematic/Make/Brake
FAh Clears keyboard buffer and sets default scan code set. [1]
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.
Table 5-16. (Continued)
8042-To-Keyboard Commands
Command Value Description
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