User`s guide

The directory identifies each file with an eight-character filename and a three-
character filetype. Together, these fields must be unique for each file. Files with the
same filename and filetype can reside in different user directories on the same drive
without conflict. Under the banked version of CP/M 3, a file can be assigned an
eight-character password to protect the file from unauthorized access.
All BDOS functions that involve file operations specify the requested file by file-
name and filetype. Multiple files can be specified by a technique called ambiguous
reference, which uses question marks and asterisks as wildcard characters to give
CP/M 3 a pattern to match as it searches the directory. A question mark in an
ambiguous reference matches any value in the same position in the directory filename
or filetype field. An asterisk fills the remainder of the filename or filetype field of the
ambiguous reference with question marks. Thus, a filename and filetype field of all
question marks, ????????.???, equals an ambiguous reference of two asterisks,
and matches all files in the directory that belong to the current user number.
The CP/M 3 file system automatically allocates directory space and data area space
when a file is created or extended, and returns previously allocated space to free
space when a file is deleted or truncated. If no directory or data space is available for
a requested operation, the BDOS returns an error to the calling program. In general,
the allocation and deallocation of disk space is transparent to the calling program.
As a result, you need not be concerned with directory and drive organization when
using the file system facilities of CP/M 3.
1.6 System Operation
This section introduces the general operation of CP/M 3. This overview covers
opics concerning the CP/M 3 system components, how they function and how they
interact when CP/M 3 is running. This section does not describe the total function-
ality of CP/M 3, but simply introduces basic CP/M 3 operations.
For the purpose of this overview, CP/M 3 system operation is divided into five
categories. First is system cold start, the process that begins execution of the operat-
ing system. This procedure ends when the Console Command Processor, CCP, is
loaded into memory and the system prompt is displayed on the screen. Second is the
operation of the CCP, which provides the user interface to CP/M 3. Third is transient
program initiation, execution and termination. Fourth is the way Resident System
Ex,ensions run under CP/M 3. The fifth and final category describes the operation of
the CP/M 3 SUBMIT utility.
1-13
1.5 Disk Organization CP/M 3 Programmer's Guide