Data Structures - HP Vectra Technical Reference Manual

2.4 Data Structures
BIOS drivers require RAM data area to perform their functions. The layout and placement of the
data areas for the STD-BIOS and EX-BIOS drivers differ. This is discussed in the following
subsections.
2.4.1 STD-BIOS Data Structures
The data area for the STD-BIOS is in absolute memory locations 00400H through 005FFH, which
conforms to the industry standard. Table 2.4 summarizes the assignments within this block of
memory. Refer to Appendix B for a detailed description of these data fields.
Table 2.4
510-8105 Data Area Summary
Address
Function
400H-407H
RS-232 Communications Port Addresses
408H-40FH
Parallel Printer Port Addresses
410H-416H
System Data and Flags
417H-43DH
Keyboard Data Area
43EH-448H
Flexible Disc Data Area
449H-466H
Video Display Data Area
467H-46BH
System Data and Flags
46CH-470H
Timer Data Area
471H-473H
System Data Flags
474H-477H
Hard Disc Data Area
478H-47BH
Printer Timeout Counters
47CH-47FH
RS-232 Communications Port Timeout Counters
480H-483H
Keyboard Data Area
48BH-496H
Diskette/Hard Disc Data Area
498H-S04H
System Data and Flags
SOSH-SFFH
Reserved
18 ROM BIOS Overview