Commodore 128D - Page 197

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For transient utilities, CP/M 3.0 checks only the command keyword.
Many utilities require unique command tails. If you include a com
mand tail, CP/M 3.0 passes it to the utility without checking it. A
command tail cannot contain more than 128 characters.
How CP/M Reads Command Lines
Let's use the DIR command to demonstrate how CP/M reads com
mand lines. DIR, which is an abbreviation for directory, tells CP/M to
display a directory of disk files on your screen. Type the DIR keyword
after the system prompt, and press RETURN:
CP/M responds to this command by displaying the names of all the
files that are stored on whatever disk is in drive A. For example, if the
CP/M system disk is in disk drive A, a list of filenames like this
appears on your screen:
A:CPM+ SYS:CCP COM:HELP COM:HELP HLP:KEYFIG COM
A:KEYFIG HLP:FORMAT COM:PIP COM:DIR COM:COPYSYS COM
CP/M 3.0 recognizes only correctly spelled command keywords. If
you make a typing error and press RETURN before correcting your
mistake, CP/M 3.0 repeats or "echoes" the command line, followed
by a question mark. For example, suppose you mistype the DIR
command, as in the following example:
A>DJR
CP/M replies with:
DJR?
This tells you that CP/M cannot find a command keyword spelled
DJR. To correct typing errors like this, you can use the INST/DEL key
to delete the incorrect letters. Another way to delete characters is to
hold down the CTRL key and press H to move the cursor to the left.
CP/M provides a number of other control characters that help you
edit command lines. Section 13 tells how to use control characters
to edit command lines and other information you enter at your
console.
DIR accepts a filename as a command tail. You can use DIR with a
filename to see if a specific file is on the disk. For example, to check
that the file program MYFILE is on your disk, type:
A>D/R MYFILE \
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USING CP/M MODE—Introduction to CP/M 3.0