Commodore 128 Programmer's Reference Manual page 496

486 COMMODORE 128
COMMUNICATION BETWEEN MODULES
The BIOS loads the CCP into the TPA at system cold and warm starts. The CCP moves
the Program Loader Module to the top of the TPA and uses the Program Loader Module
to load transient programs.
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GENERAL CP/M 3.0 SYSTEM LAYOUT
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The Commodore 128 computer is a two-processor system, with the 8502 as the primary *->
processor and the Z80 as the secondary processor. The 8502 has the same instruction set
as the 6502. The Z80's primary function is to run CP/M 3.0. This section describes the | j
general requirements and methods for implementing CP/M 3.0 on the C128. ij
When CP/M is running, the normal functions of the C128 are not supported
(CP/M and BASIC cannot run at the same time). Also, CP/M does not directly support >
all the display modes of the VIC chip. (An application could be written to run under |J
CP/M that could use additional graphics capabilities, but the application would have to
keep track of all the details, such as memory maps).
CP/M 3.0 OPERATING SYSTEM U
COMPONENTS
The CP/M 3.0 operating system consists of the following three modules: the Console [J
Command Processor (CCP), the BASIC Disk Operating System (BDOS), and the Basic
Input Output System (BIOS). , |
The CCP is a program that provides the basic user interface to the facilities of the
operating system. The CCP supplies the six built-in commands: DIR, DIRS, ERASE, u
RENAME, TYPE, and USER. The CCP executes in the Transient Program Area
(TPA), the region of memory where all application programs execute. The CCP contains j I
the Program Loader Module, which loads transient (applications) programs from disk U
into the TPA for execution. On the Commodore 128, a 58K to 59K TPA area is provided
for CP/M. | I
The BDOS is the logical nucleus and file system of CP/M 3.0. The BDOS \J
provides the interface between the application program and the physical input/output
routines of the BIOS. i t
The BIOS is a hardware-dependent module that interfaces the BDOS to a particu- M
lar hardware environment. The BIOS performs all physical I/O in the system. The BIOS
consists of a number of routines that are configured to support the specific hardware of ■
the target computer system (in this case, the Commodore 128).
The BDOS and the BIOS modules cooperate to provide the CCP and other ^
transient programs with hardware-independent access to CP/M 3.0 facilities. Because
the BIOS can be configured for different hardware environments and the BDOS remains | j
constant, you can transfer programs that run under CP/M 3.0 to systems with different LJ
hardware configurations.
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