Compaq EN Series Technical Reference Manual page 99

Chapter 4 System Support
87307 GPIO Utilization
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): Cover Lock Detect.
Read 0, no solenoid
Read 1, solenoid
5 GPIO15 (config. as output): Cover Alarm Clear.
Write 0 to clear alarm.
4 GPIO14 (config. as input): Cover Removed Detect.
Read 0, cover has been removed
Read 1, cover is secure
3..0 GPIO13-10 (config. as input):
Backplane identification (BP_ID3-0)
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..0 GPIO22..20 Not Available
GPIO Port 2 Direction/Output Type/PU Cntrl., I/O Addr. 07D-07Fh, (87307 I/O
Controller)
4-50 Compaq Deskpro EN Series of Personal Computers
Desktop and Minitower Form Factors
Third Edition - September 1998