ACT apricot - Page 241

GUIDE TO THE BIOS
Below is a description of all the sections illustrated in the
memory map:
VECTORS
Main hardware and software Interrupt and Jump vectors.
Used for service call requests from both hardware and
software.
POINTERS
lK of double and single word pointers, jump tables and
constants,
most of which are used by the BIOS, but can also
be
used or changed by applications software. Table 2 shows
all relevant addresses, with their corresponding functions:
Table 2 -- Pointer/constant area
HEX ADDRESS CONTENTS Type*
0400-04FF
BOOTSTRAP ROM WORKING AND COMMUNICATION AREA
0402-0403 Apricot memory size in paragraphs
S
0408-0409 Drive number that the system was booted off
S
040A-040D Pointer to configuration table in bootstrap D
040E-0411 Pointer to BPB image in bootstrap D
0500-05FF lOP (8089) WORKING AND COMMMUNICATION AREA
0500-0505
Channel control block (CCB), channel 1
0508-051D Channel control block (CCB), channel 2
0600-06FF SPECIAL JUMP TABLE
0600-0603 Long Control Device jump-table
T
0610-067F Reserved
0700-07FF BIOS CONFIGURATION AND COMMUNICATION VARIABLES
0700-0703 Pointer to main configuration table D
0704-0705 Length of configuration block in bytes C
0706-0709
Pointer to active character font D
070A-070B Length of font in bytes C
070C-070F
Pointer to Apricot logo in the bootprom D
0710-0711 Length of logo in bytes C
0712-0715
Pointer to active keyboard tables D
0716-0717 Length of keyboard tables in bytes C
0718-071B
Pointer to the default (boot) keyboard table D
071C-071D Length of default table in bytes C
* S=single word, D=double word, T=table, C=constant
Single word values are two bytes long, the low byte
containing the value required.