HP Vectra Technical Reference Manual page 388

C.10 EX-BIOS Checksum Byte
(CMOS Address 28H)
This byte contains the 'checksum which is used to verify the contents of the EX-BIOS CMOS data
locations. This checksum is computed each time one of these locations is modified using an EX-
BIOS CMOS function.
If bit 7 of byte 29 is 1 then
CMOS_EX_BIOS_CRC
=
[29J
+
[2AJ
+
[2BJ
+
[2CJ
If bit 7 of byte 29 is 0 then
CMOS_EX_BIOS_CRC
=
[29J
+
[2AJ
+
[2BJ
: 8
bit carryout
: 8
bit carryout
C.11
EX-BIOS Reserved Bytes (CMOS Address
29H-2CH)
These bytes are reserved by EX-BIOS. They are included in the EX-BIOS checksum byte at CMOS
address 28H.
Table C.l 0
CMOS_HPCONFIG (CMOS Address 29H)
Bit
Data
7 0
1
6
0
1
4-1
0
0
1
Definition
Do not include byte 2C in checksum (default). Note: this bit is not
reset during a <CTRL>-<Alt>-<Sys req> reset sequence
Include byte 2C in checksum
Select the first ROM video adapter as primary (default)
Select the second ROM video adapter as primary
Reserved
Manufacturing test disabled
Manufacturing test enabled
CMOS Memory Layout and Real-Time Clock 379