DOS Programs (2)

Internal and External Commands

Internal and External Commands: There are  two kinds of DOS commands. These are called internal and external. The internal commands are loaded into memory when DOS is booted. Internal commands are always available for your use, although they are not seen when you display the disk directory of filenames on your screen.

Some internal commands are:

COPY                               copies files

DEL or ERASE               delete files

DIR                                  list are directory of filenames on the logged disk

PROMPT                         changes the form of the system prompt

REN                                 rename files

TYPE                               display a named file on the screen

External commands are conventional program files. These files can be deleted, copied and even renamed. Their filenames are displayed  when DIR lists a directory on the screen. Some examples frequently used external commands are:

CHIDR                           change directory (DOS version 2.0 and higher)

CHKDSK                       check the available space on the selected disk

CLS                                clear screen

COMP                            compare files

DISKCOMP                   compare disks

DISKCOPY                    make verbatim copies of  the source disk

DOSSHELL                   display file management menus (DOS version 4.01 and 5.0)

FORMAT                      organize new disks for use with DOS

DOS Program Summary  Table 1-3  is a summary of DOS commands. In addition to commands names and descriptions, the DOS version number and the type of command are listed. In the Type column, I represents internal, E is used for external.

Table 1-3  DOS Command Summary

Device Designations:  A device designation is a reserved abbreviation, followed by a colon, which stands for different computer devices. For example designations for disk drives A and B are A: and B:. The device designation for your keyboard and screen, referred to as the console, is CON:. Like DOS commands, device designations can be typed in either uppercase or lowercase. So the designation "con:" is interpreted by DOS as "CON:." Table 1-4 is a list of DOS device designations and their meanings.

Table 1-4  Device Designations

With this background in place, move to Section 2 and begin learning how to use DOS.