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MS-DOS.
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The Microsoft Disk Operating System (MS-DOS) is a group of programs that
controls the running and operation of the computer. It provides an interface
between the operator and the computer.
DOS allows communication with the Central Processor Unit (CPU), the monitor,
the disk drives, the printer, and other peripherals. It enables the
manipulation of program and data files stored on diskette or hard disk.
DOS has a command library of over 40 commands that provide the environment
for handling files, developing programs and running applications. It should
be noted that Turbo Pascal allows an easy switch between the TP environment
and DOS.
The file handling commands of DOS allow the operator to copy and delete
files, copy entire diskettes, display the contents of files, etc., but also
to group files in a hierarchical directory structure. There is also a Line
Editor called EDLIN and a DEBUG utility.
Although GW-Basic is usually provided with DOS when a PC is purchased, other
high-level languages, such as Turbo Pascal must be provided as additional
software.
When the computer is switched on, DOS is initialized, provided it is either
on the hard disk or on a diskette in drive A. After initialization, some
DOS commands are memory resident, and these are called internal commands.
Others, known as external commands, remain on disk.
The internal commands, which are part of the command processor, are not seen
on a directory listing and comprise the following:
BREAK DEL(ERASE) MKDIR(MD) SET
CHDIR(CD) DIR PATH SHIFT
CLS ECHO PAUSE TIME
COPY EXIT PROMPT TYPE
CTTY FOR REM VER
DATE GOTO REN(RENAME) VERIFY
IF RMDIR(RD) VOL
External commands reside on disk as program files, with extension names of
.COM, .EXE, or .BAT, and include the following:
ASSIGN EDIT GWBASIC REPLACE
ATTRIB EDLIN HEXDUMP RESTORE
BACKUP EXE2BIN JOIN SELECT
CHKDSK FC LABEL SHARE
COMMAND FDISK LINK SORT
COMP FIND MODE SUBST
DEBUG FORMAT MORE SYS
DISKCOMP GRAFTABL PRINT TREE
DISKCOPY GRAPHICS RECOVER XCOPY
DOS enables a commonly executed series of commands to be grouped together
into a single file, called a batch file, that can be executed by typing the
file name. e.g. a file START.BAT would enable a certain process to be started
by typing START and pressing the ENTER key.
The AUTOEXEC.BAT file is a special form of batch file which, if present, is
automatically executed at system initialization. A simple autoexec.bat file,
suitable for Turbo C running on the hard disk drive, is shown below:
PATH c:\;c:\tc;c:\tc\include /*set path from root to other directories*/
PROMPT $P$G /*set screen prompts for directory and > */
KEYB UK 437 /*select UK keyboard and US character set*/
CLS /*clear the screen*/
VER /*display DOS version number*/
The full set of MS-DOS commands are listed in the manual supplied with the
computer. It is however worthwhile to illustrate some of the more frequently
used ones.
Most of the commands require Parameters and possibly Switches as indicated:
Parameters.
-----------
d: Disk drive letter
filename Up to eight-character name of the file on disk.
filespec Disk drive letter and filename.
path Disk drive letter and directory location.
pathname Path to the name of the file
Delimiters, which separate commands and parameters, are:
space, comma, semicolon, or equal sign.
Switches.
---------
/F CHKDSK/F Correct any error found.
/P DIR/P Stop displaying the directory when screen full.
Press any key to continue.
/S FORMAT/S Copy the system files to the disk.
/V FORMAT/V Enter a volume label on the diskette.
/W DIR/W Display only the file names widthwise.
Commands.
---------
CD [drive:][path]
Change the current directory as indicated by 'path'.
[d:][path]CHKDSK[drive:][path][filename][/F]
Check disk and report.
CLS
Clear screen and move cursor to the home position.
COPY[pathname][pathname]
Copies one or more files.
DEL or ERASE[drive:]pathname
Deletes the specified files from disk.
DIR[drive:][pathname][/P][/W]
Lists files in current or specified directory.
[d:][[path]DISKCOPY[sourcedrive][targetdrive]
Copies the contents of a diskette onto another diskette.
[d:][path]FORMAT drive: [/S][/V]
Format a disk to receive MS-DOS files.
If 'drive' not specified the default is chosen, so take
care not to inadvertently format the hard disk.
MD (or MKDIR) path
Make a new directory.
PATH[d:]\path[;[d:]\path.....]
Display or set command search path.
REN (or RENAME) pathname filename
Renames files.
RD (or RMDIR) [drive:] path
Removes a directory.
TYPE pathname
Displays the contents of the specified file on the screen.
The display can be redirected to the printer by the
redirection indicator > followed by PRN i.e >PRN
A text file can be edited in a number of ways. In MS-DOS the Text Editor,
called EDLIN, can be used. It is usual for each computer manufacturer to
provide an additional editor (e.g. Amstrad's RPED) and of course the Turbo
Pascal EDIT facility may be used.
EDLIN.
------
From the DOS prompt the command is [d:][path]EDLIN filespec.
EDLIN then copies the file into a workspace area of memory for editing and
if all is correct displays the message 'End of input file'. Each line of
the file is numbered and is referenced by that number (n) in the edit
procedure. Some of the more important EDLIN commands are :
n Edit line n, which is displayed and a new line with the same
number is displayed to allow the modification.
[n]D Delete line.
E End the edit, save new file and return to DOS.
[n]I Insert line, before n.
Q Quit the edit and abandon changes made.
DEBUG.
------
For binary and executable files a facilty,called DEBUG, is provided. The
command is
DEBUG filespec arguments
where filespec can be the full file specification, including drive,
directory and filename. The 'arguments' refer to the parameters used by
the program under examination.
Debug responds with its own command prompt, which is a hyphen (-).
Some Debug parameters are:
address hexadecimal segment;hexadecimal offset.
bytevalue hexadecimal byte value.
range start address, end address.
Some debug commands are:
D [range] address
Display this area of memory.
E address [,bytevalue[,bytevalue]...]
Replace value at address with bytevalue.
Q
Quit debug and discard file.
W [address]
Write file to disk.
The above information is provided as a limited indication of the facilities
available under MS-DOS and is far from complete. Reference to the DOS manual
must be made for more detailed information.
There are two other important system files in DOS. The first is CONFIG.SYS
which is a text file containing a set of commands to change certain default
options selected by DOS at initialization. This file can call the second,
called ANSI.SYS, which extends the screen handling facilities.
CONFIG.SYS
----------
Some of the commands in this file are:
BREAK=[ON][OFF]
extends the [Ctrl][C] interrupt to disk read/write operations.
BUFFERS=n
changes number of buffers used in disk read/write operations.
The default is 2, but 10-20 recommended.
COUNTRY=country code
sets correct time ,date, currency and decimal separator.
DEVICE=pathname
installs a device driver, such as ANSI.SYS (see below).
FILES=n
sets the maximum number of files open concurrently.
ANSI.SYS
--------
When this file is called by CONFIG.SYS (see above), standard ANSI screen
control codes are made available. These control codes all begin with the
character ESC (decimal 27, hex 1B) followed by a left bracket and are
frequently refered to as the ANSI escape sequences. There are four groups
as follows:
Cursor Control Commands.
------------------------
Cursor Position ESC[n;mf or ESC[n;mH
moves the cursor to row n, column m
Cursor Up ESC[nA
moves cursor up n rows.
Cursor Down ESC[nB
moves cursor down n rows.
Cursor Right ESC[nC
moves cursor right n columns.
Cursor Left ESC[nD
moves cursor left n columns
and others, which save, restore, and report cursor position.
Erase Display Commands.
-----------------------
Erase Display ESC[2J
erases screen and moves cursor to home position.
Erase Line ESC[K
erases to end of line.
Attribute and Mode Commands.
----------------------------
Set Display Mode ESC[=nh
sets screen mode.... n=0 is 40 x 25 bllack & white.
.
n=4 is 320 x 200 color
etc.
Set Graphics ESC[n;..;km
where n...k take the values as follows:
0 all attributes off.
1 bold
....
30 black foreground 40 black background
31 red foreground 41 red background
.....
37 white foreground 47 white background
Keyboard Control Commands.
--------------------------
Define Key ESC[n;.....;np
Assigns one or more characters to be produced when
a specified key is pressed. The first 'n' specifies
the key to be defined (ASCII 1 to 127) or if a key
combination or function key then 0;n must be used.
The last n is the character(s) to be produced, and
can be a string enclosed in double quotes.
e.g. ESC[0;68;"dir|sort|more";13p
redefines the function key F10 for a directory
list, piped to sort and more commands.
Restore Key ESC[n;....;np
where the first n and second n are the same.
e.g. ESC[0;68;0;68p
restores the F10 key to its original meaning.