Pointing Device Interface Operation; Keyboard/Pointing Device Interface Programming; Table 5-17. Keyboard /Mouse - Compaq Deskpro 4000 Technical Reference Manual

Chapter 5 Input/Output Interfaces
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

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 87307 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 PnP configuration registers are accessed through I/O registers 15Ch (index) and 15Dh
(data). The keyboard and mouse interfaces are initiated by firmware selecting logical device 0 or
1 of the 87307. This is accomplished by the following sequence:
1. Write 07h to I/O register 15Ch.
2. Write 00h or 01h to I/O register 15Dh (for selecting the keyboard or mouse interface).
3. Write 30h to I/O register 15Ch.
4. Write 01h to I/O register 15Dh (this activates the interface).
The parallel interface configuration registers are listed in the following table:
Table 5–17. Keyboard/Mouse Interface Configuration Registers
Keyboard/Mouse Interface Configuration Registers
Index
Address Function
30h Activate
31h I/O Range Check [1]
60h Base Address MSB [1]
61h Base Address LSB [1]
62h Command Base Address MSB [1]
63h Command Base Address LSB [1]
70h Interrupt Select
71h Interrupt Type
74h DMA Channel Select
75h Report DMA Assignment
F0h Configuration Data [1]
NOTES:
[1] Keyboard I/F only.
[2] Keyboard I/F / Mouse I/F
5-30 Compaq Deskpro 4000 and 6000 Personal Computers
featuring the Pentium II Processor
Table 5-17.
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
RO
R/W
First Edition – October 1997
Reset
Value [2]
01h / 00h
00h / na
02h / na
78h / na
00h / na
00h / na
01h / 0Ch
01h / 01h
04h / 04h
04h / 04h
-- / na