2 System Board
| described on page 37. |
|
RTC | The | |
| 20 ppm (parts per million). The configuration RAM is implemented as 256 | |
| bytes of CMOS memory. |
|
Serial EEPROM | This is the | |
| 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 | GPIO11 |
|
|
Auto soft lock | GPIO12 |
|
|
Backplane identification BPID0 (always =0); (see BPID1, below) | GPIO13 |
|
|
Host bus frequency selection, as indicated by | GPIO14 |
|
|
Host bus frequency selection, as indicated by | GPIO15 |
|
|
Serial EEPROM clear (as per | GPIO16 |
|
|
Ratio of processor frequency to processor local bus frequency (as per | 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 |
|
|
27