MS-DOS-OPERATING SYSTEM

MS-DOS v6.22

IO.SYS - Interface between main operating system code and the hardware
MSDOS.SYS - Main operating system code
COMMAND.COM - Interface between main operating system code and the user

NB. If any of the core files are missing or corrupt the MS-DOSboot sequence will fail.

Boot Sequence

PC is switched ON
Signal is sent to the motherboard via the POWER GOOD wire (orange)
ROM BIOS performs POST (Power On Self-Test)
ROM BIOS references CMOS RAM (comparison)
ROM BIOS searches for the boot sector/MBR on the FD/HDD
The Boot Code searches for and loads IO.SYS
IO.SYS loads MSDOS.SYS
The Boot Code searches for and loads CONFIG.SYS
The Boot Code searches for and loads COMMAND.COM
The Boot Code searches for and loads AUTOEXEC.BAT

Internal Commands

These commands are less complex and are imbedded within COMMAND.COM

CD or CHDIR

Displays the name of or changes the current directory.

CHDIR [drive:][path]
CHDIR[..]
CD [drive:][path]
CD[..]

Type CD drive: to display the current directory in the specified drive.
Type CD without parameters to display the current drive and directory

MD or MKDIR

Creates a directory.

MKDIR [drive:]path
MD [drive:]path

RD or RMDIR

Removes (deletes) a directory.

RMDIR [drive:]path
RD [drive:]path

TYPE

Displays the contents of text files.

TYPE [drive:][path]filename

CLS

Clears the screen.

CLS

DATE

Displays or sets the date.

DATE [date]

Type DATE without parameters to display the current date setting and a prompt for a new one. Press ENTER to keep the same date.

TIME

Displays or sets the system time.

TIME [time]

Type TIME with no parameters to display the current time setting and a prompt for a new one. Press ENTER to keep the same time.

DIR

Displays a list of files and subdirectories in a directory.

DIR [drive:][path][filename] [/P] [/W] [/A[[:]attributes]]
[/O[[:]sortorder]] [/S] [/B] [/L] [/V] [/4]

[drive:][path][filename]
Specifies drive, directory, and/or files to list.
(Could be enhanced file specification or multiple filespecs.)
/P Pauses after each screenful of information.
/W Uses wide list format.
/A Displays files with specified attributes.
attributes D Directories R Read-only files
H Hidden files A Files ready for archiving
S System files - Prefix meaning not
/O List by files in sorted order.
sortorder N By name (alphabetic) S By size (smallest first)
E By extension (alphabetic) D By date & time (earliest first)
G Group directories first - Prefix to reverse order
A By Last Access Date (earliest first)
/S Displays files in specified directory and all subdirectories.
/B Uses bare format (no heading information or summary).
/L Uses lowercase.
/V Verbose mode.
/4 Displays year with 4 digits (ignored if /V also given).

Switches may be preset in the DIRCMD environment variable. Override preset switches by prefixing any switch with - (hyphen)--for example, /-W.

COPY

Copies one or more files to another location.

COPY [/A /B] source [/A /B] [+ source [/A /B] [+ ...]] [destination
[/A /B]] [/V] [/Y /-Y]

source Specifies the file or files to be copied.
/A Indicates an ASCII text file.
/B Indicates a binary file.
destination Specifies the directory and/or filename for the new file(s).
/V Verifies that new files are written correctly.
/Y Suppresses prompting to confirm you want to overwrite an
existing destination file.
/-Y Causes prompting to confirm you want to overwrite an
existing destination file.

The switch /Y may be preset in the COPYCMD environment variable.
This may be overridden with /-Y on the command line

To append files, specify a single file for destination, but multiple files
for source (using wildcards or file1+file2+file3 format).

DEL
Deletes one or more files.

DEL [drive:][path]filename [/P]
ERASE [drive:][path]filename [/P]

[drive:][path]filename Specifies the file(s) to delete. Specify multiple
files by using wildcards.
/P Prompts for confirmation before deleting each file.

REN or RENAME

Renames a file/directory or files/directories.

RENAME [drive:][path][directoryname1 filename1] [directoryname2 filename2]
REN [drive:][path][directoryname1 filename1] [directoryname2 filename2]

Note that you cannot specify a new drive or path for your destination.

PROMPT
Changes the Windows command prompt.

PROMPT [text]

text Specifies a new command prompt.

Prompt can be made up of normal characters and the following special codes:

$Q = (equal sign)
$$ $ (dollar sign)
$T Current time
$D Current date
$P Current drive and path
$V Windows version number
$N Current drive
$G > (greater-than sign)
$L < (less-than sign)
$B (pipe)
$H Backspace (erases previous character)
$E Escape code (ASCII code 27)
$_ Carriage return and linefeed

Type PROMPT without parameters to reset the prompt to the default setting.

VER

Displays the DOS version.

External Commands

These files are larger and are stored either as .COM or .EXE files, normally in the DOS directory.