HP Vectra VL5 5 Technical Reference Manual page 27

RTC
Serial EEPROM
General Purpose I/O
described on page 37.
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.
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
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).
Reserved (HP security from Little Ben IRQ)
Ratio of processor frequency to processor local bus frequency (as per SW-4)
Auto soft lock
Backplane identification BPID0 (always =0); (see BPID1, below)
Host bus frequency selection, as indicated by SW-1
Host bus frequency selection, as indicated by SW-2
Serial EEPROM clear (as per SW-6)
Ratio of processor frequency to processor local bus frequency (as per SW-3)
Backplane identification BPID1 (desktop=1, minitower=0)
Serial EEPROM data out
Serial EEPROM data in
Serial EEPROM clock
Serial EEPROM chip select
Reserved (for fax or general purpose light)
Description
2 System Board
Chip-Set
in Setup).
GPIO number
GPIO10
GPIO11
GPIO12
GPIO13
GPIO14
GPIO15
GPIO16
GPIO17
GPIO20
GPIO21
GPIO22
GPIO23
GPIO24
GPIO25
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