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6.4 Basic Editing Commands CP/M 3 User's Guide
6.4 Basic Editing Commands
The text transfer commands discussed previously allow you to easily enter and exit
the editor. This section discusses the basic commands that edit a file.
ED treats a file as a long chain of characters grouped together in lines. ED displays
and edits characters and lines in relation to an imaginary device called the character
pointer (CP). During an edit session, you must mentally picture the CP's location in
the memory buffer and issue commands to move the CP and edit the file.
The following commands move the character pointer or display text in the vicinity
of the CP. These ED commands consist of a numeric argument and a single command
letter and must be followed by a carriage return. The numeric argument, n,
determines the number of times ED executes a command; however, there are four
special cases to consider in regard to the numeric argument:
o If the numeric argument is omitted, ED assumes an argument of 1.
o Use a negative number if the command is to be executed backwards through
the memory buffer. The B command is an exception.
o If you enter a pound sign, #, in place of a number, ED uses the value 65,535
as the argument. A pound sign argument can be preceded by a minus sign to
cause the command to execute backwards through the memory buffer, -#.
o ED accepts 0 as a numeric argument only in certain commands. In some
cases, 0 causes the command to be executed approximately half the possible
number of times, while in other cases it prevents the movement of the CP.
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