System information

CP/M also supports ED, a powerful context editor, ASM, an Intel-compatible assembler, and
DDT, debugger subsystems. Optional software includes a powerful Intel-compatible macro
assembler, symbolic debugger, along with various high-level languages. When coupled with
CP/M's Console Command Processor (CCP), the resulting facilities equal or exceed similar large
computer facilities.
CP/M is logically divided into several distinct parts:
-BIOS (Basic I/O System), hardware-dependent
-BDOS (Basic Disk Operating System)
-CCP (Console Command Processor)
-TPA (Transient Program Area)
The BIOS provides the primitive operations necessary to access the disk drives and to interface
standard peripherals: teletype, CRT, paper tape reader/punch, and user-defined peripherals. You
can tailor peripherals for any particular hardware environment by patching this portion of CP/M.
The BDOS provides disk management by controlling one or more disk drives containing
independent file directories. The BDOS implements disk allocation strategies that provide fully
dynamic file construction while minimizing head movement across the disk during access. The
BDOS has entry points that include the following primitive operations, which the program
accesses:
-SEARCH looks for a particular disk file by name.
-OPEN opens a file for further operations.
-CLOSE closes a file after processing.
-RENAME changes the name of a particular file.
-READ reads a record from a particular file.
-WRITE writes a record to a particular file.
-SELECT selects a particular disk drive for further operations.
The CCP provides a symbolic interface between your console and the remainder of the CP/M
system. The CCP reads the console device and processes commands, which include listing the
file directory, printing the contents of files, and controlling the operation of transient programs,
such as assemblers, editors, and debuggers. The standard commands that are available in the CCP
are listed in Section 1.2.1.
The last segment of CP/M is the area called the Transient Program Area (TPA). The TPA holds
programs that are loaded from the disk under command of the CCP. During program editing, for
example, the TPA holds the CP/M text editor machine code and data areas. Similarly, programs
created under CP/M can be checked out by loading and executing these programs in the TPA.
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