ACT apricot - Page 243

GUIDE TO THE BIOS
SECONDARY CACHE
The secondary disk cache is an extension of the primary
cache, that can be used when there is no graphics RAM
required. The Boot ROM character set is also placed here at
boot-up, so characters such as the Apricot logo can be
displayed on the screen.
PRIMARY CACHE
This is used as the main disk cache memory. Utilising the
now-vacant SYSINIT space, 6K of primary cache is
available. See
the section on Disk Caching for more
information.
SYSINIT
This module is provided by Microsoft to initialize the
MS-DOS operating system. It is only used once, each time
the system is booted up. Resident in the BIOS, it is "thrown
away" when it has loaded and initialized the operating
system and the memory space it occupied becomes vacant
and is used for various system purposes (see above).
BIOS CODE
The actual BIOS program. This section of memory
contains all the BIOS that the Apricot MS-DOS 2.0
implementaion uses. There are some internal tables (such
as
the keyboard tables and jump tables), all of which are
accesed by the pointers. For assembly language
programmers, this code is the primary BIOS Code Segment.
BIOS CONSTANTS
An area of code containing the constant numeric values
which are established by the BIOS at boot-up time, and
remain unchanged until the system is re-booted. For
example,
one constant is the number of disk drives that the
particular Apricot configuration has, and is accsesed by
MS-DOS and the BIOS.