Editing CP/M (section)

=== Console Command Processor ===
[[File:Commodore C128 CPM Screenshot 2 full.jpg|thumb|Screenshot showing a CP/M 3.0 directory listing using the <code>[[dir (command)|DIR]]</code> command on a Commodore 128 home computer]]

The Console Command Processor, or CCP, accepts input from the keyboard and conveys results to the terminal. CP/M itself works with either a printing terminal or a video terminal. All CP/M commands have to be typed in on the [[command line]]. The console most often displays the <code>A></code> prompt, to indicate the current default disk drive. When used with a video terminal, this is usually followed by a blinking [[Cursor (user interface)|cursor]] supplied by the terminal. The CCP awaits input from the user. A CCP internal command, of the form drive letter followed by a colon, can be used to select the default drive. For example, typing <code>B:</code> and pressing enter at the command prompt changes the default drive to B, and the command prompt then becomes <code>B></code> to indicate this change.

CP/M's command-line interface was patterned after the [[Concise Command Language]] used in operating systems from [[Digital Equipment Corporation|Digital Equipment]], such as [[RT-11]] for the [[PDP-11]] and [[OS/8]] for the [[PDP-8]].{{citation needed|date=May 2021}} Commands take the form of a keyword followed by a list of parameters separated by spaces or special characters. Similar to a Unix [[shell builtin]], if an internal command is recognized, it is carried out by the CCP itself. Otherwise it attempts to find an executable file on the currently logged disk drive and (in later versions) user area, loads it, and passes it any additional parameters from the command line. These are referred to as "transient" programs. On completion, BDOS will reload the CCP if it has been overwritten by application programs — this allows transient programs a larger memory space.

The commands themselves can sometimes be obscure. For instance, the [[Command (computing)|command]] to duplicate files is named <code>[[Peripheral Interchange Program|PIP]]</code> (Peripheral-Interchange-Program), the name of the old DEC utility used for that purpose. The format of parameters given to a program was not standardized, so that there is no single option character that differentiated options from file names. Different programs can and do use different characters.

The CP/M Console Command Processor includes [[dir (command)|DIR]], [[ERA (CP/M command)|ERA]], [[ren (command)|REN]], [[SAVE (CP/M command)|SAVE]], [[TYPE (CP/M command)|TYPE]], and [[USER (CP/M command)|USER]] as [[Shell builtin|built-in]] commands.<ref name="CPM22"/> Transient commands in CP/M include [[Assembler (computing)|ASM]], [[DDT (CP/M command)|DDT]], [[DUMP (CP/M command)|DUMP]], [[ED (CP/M command)|ED]], [[LOAD (CP/M command)|LOAD]], {{ill|MOVCPM|pl|MOVCPM (CP/M)}}, [[Peripheral Interchange Program|PIP]], [[STAT (CP/M command)|STAT]], [[SUBMIT (CP/M command)|SUBMIT]], and [[SYSGEN (CP/M command)|SYSGEN]].<ref name="CPM22"/>

CP/M Plus (CP/M Version 3) includes DIR (display list of files from a directory except those marked with the SYS attribute), [[DIRSYS (CP/M command)|DIRSYS]] / [[DIRS (CP/M command)|DIRS]] (list files marked with the SYS attribute in the directory), [[ERASE (CP/M command)|ERASE]] / ERA (delete a file), [[RENAME (CP/M command)|RENAME]] / REN (rename a file), TYPE / [[TYP (CP/M command)|TYP]] (display contents of an ASCII character file), and USER / [[USE (CP/M command)|USE]] (change user number) as built-in commands:<ref name="CPM3_1983_PG"/> CP/M 3 allows the user to abbreviate the built-in commands.<ref name="DRI_1983_CPM3"/> Transient commands in CP/M 3 include [[SYSGEN (CP/M command)|COPYSYS]], [[DATE (CP/M command)|DATE]], [[DEVICE (CP/M command)|DEVICE]], [[DUMP (CP/M command)|DUMP]], [[ED (CP/M command)|ED]], [[GET (CP/M command)|GET]], [[help (command)|HELP]], [[HEXCOM (CP/M command)|HEXCOM]], [[INITDIR (CP/M command)|INITDIR]], [[LINK (CP/M command)|LINK]], [[MAC (CP/M command)|MAC]], PIP, [[PUT (CP/M command)|PUT]], [[RMAC (CP/M command)|RMAC]], [[SET (CP/M command)|SET]], [[SETDEF (CP/M command)|SETDEF]], [[SHOW (CP/M command)|SHOW]], [[SID (CP/M command)|SID]], [[SUBMIT (CP/M command)|SUBMIT]], and [[XREF (CP/M command)|XREF]].<ref name="DRI_1983_CPM3"/>