HP Vectra Technical Reference Manual page 31

The DH_NAME_INDEX is used to derive the
localization string index of the driver. This is given by the
function F _STIL-GET_STRING in the V_SYSTEM
driver. See Section 9 for additional information.
The DH_V_DEFAULT field contains the driver's default
~
vector address.
DH_P_CLASS and DH_C_CLASS: In conjunction, these fields indicate which drivers may be
mapped together. DH_P_CLASS and DH_C_CLASS
are bit masks. Each bit position represents a set of
drivers. If a bit is set then the driver is in that set of
drivers. The DH_P_CLASS field indicates a driver is in
from 0 to 16 different driver sets. A driver can only map
to another driver if its DH_P_CLASS field matches at
least one bit position of the other driver's
DH_C_CLASS field. Furthermore, the DH-ATR field is
another condition of mapping. The bits are defined in
Appendix G.
The DH_V_PARENT field contains a vector to the driver
that is called when the current driver receives an F_ISR
function code that it cannot or doesn't know how to
~
process.
The DH_V_CHILD field contains a vector to the driver
that is called if this driver decides it cannot handle the
request function (as long as that function is not F_ISR).
Device bus address information.
EX-BIOS Global Data Area
The method for locating the EX-BIOS global data area is found in the "EX-BIOS Data Area Map"
of Appendix B. The EX-BIOS global data area is shared between several EX-BIOS drivers. It
contains temporary and permanent variables that are required by the BIOS to function properly.
Some of these variables can be modified by application programs. As with any modification to
the STD-BIOS data area, care should be taken with the EX-BIOS global data area. Table 2.6
~,
defines the contents of this area. -,
22 ROM BIOS Overview