Chapter 5 Input/Output Interfaces
5-18
Compaq Deskpro EXS and Workstation 300 Personal Computers
Featuring the Intel Pentium 4 Processor
First Edition – December 2000
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.
5.6.3.1 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 LPC47B357 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.
The keyboard interface configuration registers are listed in the following table:
Table 5–14
. Keyboard Interface Configuration Registers
Table 5-14.
Keyboard Interface Configuration Registers
Index
Address
Function
R/W
30h
Activate
R/W
70h
Primary Interrupt Select
R/W
72h
Secondary Interrupt Select
R/W
F0h
Reset and A20 Select
R/W
