Compaq Deskpro 4000 Technical Reference Manual page 91

The 87307 I/O Controller provides 11 general purpose pins that can be individually configured as
either inputs or outputs. These pins are mapped as two general purpose ports and utilized as
shown below.
GPIO Port 1 Data, I/O Addr. 078h, (87307 I/O Controller),
Bit Function
7 GPIO17 (not used)
6 GPIO16 (config. as input): Hood Lock Detect.
Read 0, no solenoid
Read 1, solenoid
5 GPIO15 (config. as output): Hood Alarm Clear.
Write 0 to clear alarm.
4 GPIO14 (config. as input): Hood Removed Detect.
Read 0, cover has been removed
Read 1, cover is secure
3..0 GPIO13-10 (config. as input):
Bus/Core Ratio (see chapter 3)
GPIO Port 1 Direction/Output Type/PU Cntrl., I/O Addr. 079-07Bh, (87307 I/O
Controller)
GPIO Port 2 Data, I/O Addr. 07Ch, (87307 I/O Controller),
Bit Function
7..4 GPIO27..24 Not Available
3 GPIO23 (config. as input): Ring Detect
Read 0, no ring received
Write 1, ring detected
2 GPIO22 (config. as output): NIC I/F Enable/Disable.
Write 0 to enable.
Write 1 to disable.
1 GPIO21 (config. as output): SCSI Enable/Disable.
Write 0 for normal operation
Write 1 for low power mode
0 GPIO20 (config. as output): Audio Enable/Disable.
Write 0 to enable.
Write 1 to disable.
GPIO Port 2 Direction/Output Type/PU Cntrl., I/O Addr. 07D-07Fh, (87307 I/O
Controller)
Compaq Deskpro 4000 and 6000 Personal Computers
featuring the Pentium II Processor
First Edition–- October 1997
Technical Reference Guide
4-45