Chapter 5
Basic
1/0
System
(BIOS) Organization
The version
of
CP
/M-86
you have purchased
is
set
up
for operation with the
NEC
APC. All hardware dependencies are concentrated in subroutines which are collec-
tively referred
to
as the Basic
Input/Output
System,
or
BIOS.
NEC
has modified
these subroutines
to
tailor
CP/M-86
to
fit the
APC
operating environment. The
BIOS has been customized,
and
so
is
referred to as the CBIOS.
The
BIOS consists
of
three sections:
standard
BIOS functions, escape sequence
functions,
and
extended functions. The latter two sections
of
the BIOS contain
APC-specific modifications
to
CP
/M-86
that
are referred
to
collectively as
advanced
BIOS functions. They are described in
Chapter
6.
Standard
BIOS func-
tions, for
both
floppy diskette
and
hard
disk systems, are discussed in this chapter.
In
both
chapters, entry points
and
variables are defined as necessary
and
BIOS
tables are referenced. The discussion
of
Disk Definition Tables
is
treated separately
in Chapter 7
of
this manual. Listings are supplied
on
the distribution diskette.
The relationship
among
applications programs, the BDOS,
and
the BIOS
is
shown
in Figure 5-1.
Figure
5-1
APC CBIOS Function Calls
EXTENDED
FUNCTION CALLS
5-1
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