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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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