HP Vectra VL 5/xxx Series 5 User Manual
Page 27
27
2 System Board
Chip-Set
described on page 37.
RTC
The real-time clock (RTC) is 146818A-compatible. With an accuracy of
20 ppm (parts per million). The configuration RAM is implemented as 256
bytes of CMOS memory.
Serial EEPROM
This is the non-volatile memory which holds the default values for the CMOS
memory (in the event of battery failure, or the user pressing
in Setup).
General Purpose I/O
There are several general purpose I/O pins. Some of these are used on the
HP Vectra to sense the current settings of system board switches (page 31
and page 39).
Description
GPIO number
Reserved (HP security from Little Ben IRQ)
GPIO10
Ratio of processor frequency to processor local bus frequency (as per SW-4)
GPIO11
Auto soft lock
GPIO12
Backplane identification BPID0 (always =0); (see BPID1, below)
GPIO13
Host bus frequency selection, as indicated by SW-1
GPIO14
Host bus frequency selection, as indicated by SW-2
GPIO15
Serial EEPROM clear (as per SW-6)
GPIO16
Ratio of processor frequency to processor local bus frequency (as per SW-3)
GPIO17
Backplane identification BPID1 (desktop=1, minitower=0)
GPIO20
Serial EEPROM data out
GPIO21
Serial EEPROM data in
GPIO22
Serial EEPROM clock
GPIO23
Serial EEPROM chip select
GPIO24
Reserved (for fax or general purpose light)
GPIO25