(updated 12/16/2012)

DOS Handbook for PCs...

© 1992 Cam Longhurst

Note : this handbook was intended for PCs running DOS 5.0 and Windows 3.1. Some commands have changed, and many new ones have been added. (It is amazing though, how many of the issues and functions described below have remained literally unchanged.)

Included : 

Introduction Overview Troubleshooting Hardware Firmware Software

Disk space management Memory Screen display Keyboard

File types File attributes Directory- and file names Boot sequence Config.sys Autoexec.bat

Internal commands External commands System masters Backing up your files Your mission...

Introduction - The mystical one...

Take on faith that the universe we live in was created for some meaningful end. From birth, humans are indoctrinated with a life-serving way of thinking called reasoning. Humans believe that their chance of survival and the quality of their lives are greatly improved - with a better understanding of one's self and the world one lives in.

The dialectic is considered to be the purest form of reasoning. Dialectic arguments juxtapose two opposite sides of an issue for comparison. Logic is used to determine the opposing sides, with intuition playing a large part in limiting the range of ideas for examination. From this, reasonable thinkers can induce new values, and arrive at the lesser truths.

Humans, generally, are limited in their ability to juggle several ideas at once in logical consideration. Limitations in short-term memory and processing capacity, lapses in concentration, and a lacking in experience and dedication often make even simple truths unavailable to the average man. And it is not likely that humans (generally) in the near future will become any more capable than they are now. It would be good, though, to clear away some of the routine thinking and mental chores we do daily, so we might see something of the larger picture...

Human experience has acquainted us with a number of physical laws and pervasive systems for which we have developed extensive analogies. These inventive analogies habitually contain diametrically-opposable nomenclature and units of measure - we think best that way. Humans are taught to think in terms of true or false, right or wrong, good or bad. Idealistically, the world is black or white. This kind of thinking can be overlaid directly on the physical system of a computer. In a word, computers are capable of simulating dialectical, analogical reasoning.

Computers are electronic devices, constructed to "think" like us, for us. Computers make use of direct-current electricity - with its positive or negative charges; various switches - which can either be on or off; semi-conductor technology - with the ability to either pass current or not; and magnetic storage - where bits of information are stored as either north or south charges. For us to communicate with them, our input is translated into binary form, in which only zeroes and ones are used. Then to have computers perform for us, to make decisions for us, we need only instill our values and our methods of discrimination.

While computers can perform tasks with an efficiency and speed that is sometimes frightening, they are not alive and do not think for themselves. Their capabilities come from the designers, assemblers, and programmers, but their usefulness comes from their creative and effective application by clear-thinking users. At best, they are extensions of our form. If sometimes they seem alive, it is only when we see ourselves or someone else within them.

An overview...

The computer you have may be capable, but it is not intelligent. By itself, your computer does little more than update its memory of the current time and date. You must know what you want to do, and how to do it, before you can efficiently use your computer to do your work better and faster.

You can issue commands to your computer by inputting them through your keyboard or mouse. You will find, though, that computer languages are rudimentary, bordering on the eccentric, and if you do not issue your commands correctly, your computer may come back to you with a cryptic message and coldly wait for you to try again. If you issue a command correctly, but it is not what you really want to do, your computer will, without comment, dutifully comply. And, if you issue a potentially harmful command, your computer may (or may not) warn you of impending doom, but will again, dutifully comply.

A number of operations you will want to perform on your system are best understood by imagining that you are inside the housing of your computer - walking about its three-dimensional structure like you might walk about the structure of your own office building. Imagine that all the hardware you have, and all your system files, can be found in your building's basement; and all the directories and DOS commands you might deal with are on the ground floor.

Environments like Windows are overlays for the ground floor, and high-level programs you may have (like Dbase IV or Wordstar) reside on the upper floors. To continue the analogy, efficient upper floor operations are reliant on error-free ground floor operations, and all operations are reliant on properly-installed hardware and system software in the basement.

About troubleshooting...

When you have problems with your computer, look carefully at the information you have available to you, so you can determine how you might go about correcting the situation.

About the hardware...

Computing technology has moved from mechanical clock-like switching, through vacuum-tube and transistor switching, up to the present semi-conductor switching, and is on its way to who-knows-where.

Semi-conductor switching is housed in integrated circuits (ICs). At the heart of ICs are silicon chips. Impure silicon, with just the right amount of impurities, has been found to be the best material from which to make semi-conductors. The most important of these chips is your central processing unit or CPU. The speed of any given computer is determined primarily by how fast information can be processed by this chip. Your CPU, along with various other pieces of electronic circuitry, ROM and RAM chips, make up your system's motherboard.

Read-only memory (ROM) chips have everything to do with your system's general operation. Random access memory (RAM) chips hold your active programs. CMOS chips hold useful things like the time and date, and other personal information about your particular system. ROM memory exists for the life of the chip, RAM memory is lost when your system is turned off. CMOS memory would die on power-off too, so to retain it, most systems have these chips connected to a small rechargable battery on the motherboard.

Extension cards that plug in to your motherboard can also have ROM and RAM chips that are dedicated to the functions of these cards. And virtually all computers have a drive controller card and some kind of multi-function input/output (IO) card. Peripherals, such as your printer or external modem or mouse would be plugged into such cards.

Another card commonly found these days, is a memory expansion card. The latest consumer programs are demanding more and more memory to achieve acceptable performance.

To save your data, your system will likely have at least a floppy drive (or two) and a hard drive of some capacity. Floppy drives are your major link to the rest of the computer world. Programs and data you acquire generally comes on floppy disks, and data you export generally goes on floppy disks. Though your drives are built into the housing of your computer, they are detachable for repair or replacement. The data on your disk drives is stored magnetically, and as such is retainable without a constant power supply.

The major output device of your computer is your screen display. It is connected through its own dedicated port, at the back of your computer. Other output devices are your printer - usually connected to your parallel port, and your modem - connected to your serial port. On the input side, you have your keyboard - with its own dedicated port, your mouse - connected to a dedicated port or to a second serial port, and your modem again - which can receive data as well. Other devices that can be considered input devices include scanners, light pens, touch-screen monitors, and microphones. Other output devices include plotters and external sound systems, and, loosely, robotic elements.

Hardware maintenance...

Your computer and all your peripheral devices will need to be installed and configured properly, for trouble-free operation. All components come with instruction manuals and everything you'll need to connect them. Read the manuals, then store them in a safe place near your computer. Fill out the warranty cards and mail them in, to take advantage of any warranty service or user support. Buy a power bar or power distributor with surge protection, and connect all your components to it. Stay clear of electrical circuits with heavy-draw appliances, like refrigerators with periodic start-ups. Purchase the appropriate floppy drive cleaning kits, and follow the instructions for cleaning your floppy drives. Comply with any ink or toner specifications for your printer, and use the recommended paper types.

Use a vacuum cleaner to remove any accumulating dust from your equipment. A mild dish detergent in warm water can be used to clean grime from the outer surfaces; dampen a cloth with the mixture and wipe down these surfaces periodically. Be aware that your keyboard has circuitry directly below the keys, so any liquid running down between the keys can cause you grief. (If you spill something into it while your machine is running, you're best to shut down and let it dry.) Glass cleaner can be used on the monitor face. If you ever have your computer open, you can lightly vacuum any dust found inside, or use compressed air to blow the dust out. (If your fans get loud or noisy, dust accumulation can be the cause.)

About firmware...

Chips that have been programmed with operating system instructions or other such data, are referred to as firmware. A good deal of your operating system exists on a handful of ROM chips mounted directly on your motherboard.

About software...

The broad range of programming that needs to be loaded into RAM memory to operate is called software. This term would include your DOS operating system, any DOS commands, any commercial programming you may acquire, and any custom programming you may have written or actually write for yourself. Any remaining files you might have on your system would be considered data files.

Disk space management...

Data on your floppy disks and hard drive is arranged in a pattern of tracks and sectors. When formatting a disk, tracks are laid down in a series of circles around the disk's center, with the space between being determined by the quality and type of the drive. The tracks are subdivided into "pie-slice" sectors, with each sector capable of holding 1/2 a kilobyte of information. Groups of sectors are known as allocation units, with the number of sectors in an allocation unit being determined by the drive capacity.

DOS keeps two formal records of your data files on a disk. The file allocation table (FAT) contains the record of where every file is on your disk, and the directory contains the name, file size, the date and time of creation, and several attributes for every one of your files. While disk sizes may vary, the way files are kept is uniform for all drive types.

In organizing your hard drive, reserve the space in your root directory for the two hidden system files (IO.SYS and MSDOS.SYS), COMMAND.COM, AUTOEXEC.BAT, CONFIG. SYS, and any drivers you load every session. Keep your batch files in their own directory called BATS. Install your DOS commands in their own directory called DOS. Many users have this same efficient structure employed on their systems.

Programs that consist of only one or two files can be kept in a sub-directory of similar files, under a short name that describes them all. Utilities - commands similar to DOS that perform maintenance functions - should be kept in a directory named UTIL, for example. Programs, or families of programs (like Norton's Utilities), should be kept in sub-directories all their own. Use short (but meaningful) directory names for ease of entering. Conventionally, Norton's Utilities reside in a sub-directory called NU, Fastback's group of files reside in FB, Wordstar program files reside in WS, and so on.

Programs that create data files should have sub-directories for these data files, to keep them separated from the program files themselves. When making backups, program files and data files get backed up to different degrees, so it's important to incorporate and maintain this simple separation. Data files can also be subdivided and stored in several sub-directories. You may need to separate them on the basis of who owns the files, or what kind of files they are. Use sub-directories to your advantage: they can organize, simplify and speed up your general operations.

Keep applications that require a certain environment ( like Windows) in a tree structure created for that environment. For example, Windows program files reside in the C:\WN sub-directory. AMIPRO, a Windows-based application, resides in C:\WN\AP, rather than C:\AP. The related AMIPRO data files reside in C:\WN\AP\DOCS.

Alpha-sorting of files by name is the simplest way of keeping directories tidy. Delete program-generated back-ups of files that you don't edit anymore (look for extensions like .BAK or .~??. Temporary files ($ in their extensions) may be left over from an old session, and should be deleted if not in immediate use. Also, contiguous storage of the data in your files is important for quick access, so optimize your disk space weekly with a file management utility intended for this purpose.

About memory...

Years ago, when the technology behind RAM memory was not so refined, IBM-type computers operated with a small amount of available memory for any program you might have to run. Today, 640K (kilobytes, each kilobyte being 1,024 bytes) is the standard amount of available RAM most systems have before the operating system is loaded. Memory beyond the 640K is either expanded or extended, with many systems now operating with memory in excess of 4 MEG (megabytes, a megabyte being 1,048,576 bytes).

The optimum memory location for program occupancy used to be just after DOS in the first 640K, but DOS can now be loaded high in the expanded RAM, and data files can be loaded into the extended RAM. This puts your preferred programming in the most responsive memory available, thus improving the overall performance of your computer (for the mere cost of the additional memory!).

The organization and utilization of your available memory can be given over to a memory manager, a program that can analyze your system and arrange your configuration for optimum performance. (This is only necessary if, in fact, you do have expanded or extended memory.) Quarterdeck's Expanded Memory Manager (QEMM) is such a program.

MS DOS 5.0, intrinsically, has the ability to load DOS into high ram with the LOADHIGH command. Also, 5.0 comes with EMM386.EXE for 386 users with expanded memory. Consult your DOS 5.0 manual for instructions on how to use these commands.

Remember to save your data before powering off your computer. Only ROM and CMOS memory is retained after power-down, RAM memory is lost forever. (For disk storage, data is encoded as north and south magnetic charges, and an electro-magnetic device writes the data onto, and reads off of, the magnetic media. Once your data has been saved to disk, you may safely power down.)

The screen display...

You computer can display data in two ways - a grid of characters or an array of pixels. For characters, your screen is usually divided into 80 columns and 25 rows. A box of 7 x 8 pixels (picture elements, appearing as dots on your screen) is the room alloted for each character.

In the case of graphics, the screen display is comprised of an array of pixels, some 320 (or 640) x 200 of them. (Newer screens have exceeded these numbers and are capable of finer and sharper displays.) The pixels can either be on or off, and can be in colour, too, depending on the byte stored on the graphics memory page for that location. WYSIWYG (what-you-see-is-what-you-get) displays may look like text displays, but they are really graphic displays. The scalable and malleable characters you see are constructed from vector-like instructions, rather than pixel maps.

The WINDOWS environment and most WINDOWS applications run within Windows are WYSIWYG. Text-based applications are run through a DOS window. There is a dramatic difference in the visual presentation of any WYSIWYG application and its DOS counterpart, but the low-level operating system for both is the same.

Your keyboard...

When working from the DOS prompt, there are certain useful keystrokes to know about.

Use CTRL-S (or PAUSE key) to pause information that is scrolling by on your display. Use ESC (escape) to interrupt most processes. CTRL-C will stop most DOS functions. CTRL-BREAK will also stop most DOS functions, but there are times when neither CTRL-C nor CTRL-BREAK will have any effect at all. These keys can take several seconds (and may need to be hit several times) to have an effect. CTRL-ALT-DEL is your last resort as far as keystrokes go. If your computer is still not responding, power off, wait several seconds (for the capacitors to discharge) then power on again.

DOS has a short, one-line memory of what your last-entered DOS command line was. To repeat a previous command, try using F1 to recreate the previous line one character at a time. F3 will bring back the previous line in one shot. If you are repeating a previous command but want to change a few of the characters (perhaps to fix a syntax error or to do the same operation on a similar file name) try using F1 and F3 in combination to create most of your new command.

Hit the PRINTSCREEN key at any time to send a text copy of your present screen to your printer. (This is especially useful for noting the details of errors for future analysis.)

File types...

A file - as an entity - is stored as a series of numbers, analogically, on your hard drive or floppy disk. In this sense only, all files are the same.

System files contain the instructions your system needs to perform the many functions you need your computer to do. There are two hidden system files in your root directory that must be there for your system to boot from the C: drive. One file contains the complete disk operating system (DOS) instruction set and the other contains instructions for sending and receiving data through your input and output ports. Other .SYS files include the operating instructions for peripheral devices such as a mouse or printer. Although similar in function and format, this latter kind of system file is commonly referred to as a device driver. A file named CONFIG.SYS (that resides in your root directory) is generally used to load any drivers on booting.

Command files are programs that, when loaded and run by your operating system, allow you to perform housekeeping duties or other high-level operations like word processing or database management. Commands have either .EXE or .COM as their extension. The difference is in the loading of the file - each file type loads into a different memory location in order to run. EXEcutable files and COMmands perform the same kinds of functions in the same way. .EXE files are the product of compilers while .COM files are generated by machine language code.

There are two general types of commands. Internal commands (like DIR and CD) are part of COMMAND.COM and are loaded when your system boots. These commands are available at the DOS prompt at any time. Due to their size, external commands (like DISKCOPY and FORMAT) reside as individual files in your DOS directory, and are loaded temporarily when you enter their names and run them. To run them, DOS needs to know where these commands are. If the files are outside the default directory (where you are), you need to include their directory's name in your active path, or you can enter the path along with the command.

Many commands require follow-up details to perform their tasks. An example would be the COPY command that, if issued without "copy what?" and "to where?" follow-ups won't be able to do anything useful for you. These parameters are entered with the command name, usually in some conventional order referred to as the command's correct syntax. Commands are issued simply by entering a command line at the DOS prompt. A command line includes a command's path (if necessary) and name, followed by any parameters needed.

Sometimes DOS commands are performed in a series to accomplish some task. Command lines are entered one after another, with the result of the first often influencing the outcome of the second, and so on. An example of this might be the issuance of a directory sorting command before copying a number of files from one directory to another. Batch files are text files in which a series of commands (or one complex command) may be writtten into so you won't have to enter each command in order yourself. Batch files are like DOS programs in that you run them by entering their names (along with any necessary parameters) at the DOS prompt.

Here is an example of the text within a typical batch file...




DBASE M000000





If you find yourself entering the same series of commands over and over again to accomplish some DOS task, create a batch file (with a simple text editor or the COPY CON command) that has all the commands you have been entering them, in their correct order. Give your batch files simple meaningful names and store them in in their own directory (named BATS). Include your batch file directory in your system's path statement, so you can run these batch files from any DOS prompt. Batch files are special function text files. Their extension (BAT) allows them to be executed as a DOS program.

Text files or ASCII files are files containing text only. Commonly-used extensions are .TXT and .DOC. Text files are not interpreted. Text files are often used to transfer data from one program type to another. An example of transferring data would be the exportation of mail merge data from DBASE IV to a completely different program, like Wordstar.

Dbase has the ability to compile certain text files into Dbase-compatible routines. These text files need only be written in the Dbase programming language to be acceptable for compilation.

Many programs keep their configuration data in text files created for you during the program's installation and updated when your configuration changes. Windows creates files with the extensions .INI and .PIF for this purpose.

Any text/word processor can be used to edit the contents of text files. Be sure to use the non-document mode in word processors like Wordstar; text files become corrupt if they have control-type printing commands in them or other control-type characters for margins and the like.

Data files are created by many programs to store your particular data in. These files generally have unique formats that make them readable only by the programs that created them. As an example, DBase IV would keep most of your data in files with the extensions .DBF and .MDX. AMIPRO would keep your data in files with the extension .SAM.

Since most users have several different major programs to perform their numerous tasks, programmers now include importing and exporting functions in their programs that allow a user to import and export files that have been created in a format used by another program. Graphics programs import and export files in .TIF, .PCX, .GEM and numerous other formats. Other graphics programs and some word processing programs can read these various formats so as to include this data in an integrated report of some kind.

Make sub-directories for each of your major programs, to keep your data files in. Keeping your program and data files apart allows you to easily make exclusionary backups of your program files apart from your data files. You need only make two serviceable backups of your program files ever, but you should be making numerous daily (weekly, hourly) backups of your data files.

If your major program allows you to add your own extensions onto your data files, take advantage of this. Meaningful extensions like .DOC, .LET or .FRM can make a world of difference in identifying and managing the safe storage of your files later on.

About file attributes...

All files have several settable attributes that you can use to make your files react differently to certain commands. Files can be made to be read only (that is to say, they cannot be over-written by any DOS command attempting to do so) or, nuisance read-only files can be made read-write (accessible for moving or deletion). Hidden files are protected from being acted upon by DOS commands. True system files have the system attribute set, making them unmovable by disk optimizers, and archived files are markable as having been archived. DOS keeps these attributes along with the file name, extension, file type, size and file location in the information kept about a file in its directory entry.

Directory names and file names...

DOS has certain rules about the file and directory names you may create.

Use as many of the eight characters allowable to make up a meaningful file name. Short names are easier to type in, but a year from now you may not remember what's in the file without using its creator to examine it. Also, the possible combinations of two or three characters is far more limited than the combinations using all eight. Your chances of creating a duplicate file name are reduced with each letter you include.

To perform some DOS task or other maintenance function on a group of files, you can incorporate the wildcard capability of DOS to associate similarly-named files. For example, the command COPY *.* A: would copy every file within the directory the command was issued to the A: drive, while COPY *.BAT A: would only copy files with the extension BAT, and COPY CALENDAR.* A: would copy only files with names beginning with CALENDAR, whatever their extension.

Using a question mark (?) in place of a text character in a file name or extension will cause DOS to accept any legitimate character in its place. In a list of files such as this - MAR.DOC, APR.DOC, MAY.DOC, JUN.DOC - copying MA?.DOC or M??.DOC would include only MAR.DOC and MAY.DOC, excluding APR.DOC and JUN.DOC. (Copying ???.DOC would include them all.)

Since DOS can perform tasks on a group of files associated through the use of wildcards, you can help yourself by using the extension to identify a type of file you keep rather than using the extension as simply three more letters in the name. Perhaps you can name all your letters with .LET as their extension, or all your forms with the extension .FRM. You might also use the file name portion to group files. As an example, naming invoices JAN92_01.INV, JAN92_02.INV, etc., would allow you to copy older invoices en masse to some location for backup.

Boot sequence...

On power-up, your system is flooded with low-voltage electricity and "boots" - brings itself up to full running ability (from the phrase - pull one's self up by one's own bootstraps).

In order, your computer first "reads" the ROM and the hidden system files (like IO.SYS and MSDOS.SYS) to "learn how to do" all the things you might ask of it in your working session; things like how to read from and write to your hard drive and floppy disks, how to exchange information with your peripheral equipment, how to run programs, etc.

With all this in hand, your computer then looks for the CONFIG.SYS file in your root directory to see if you need to customize your system with the installation of any devices or the issuance of any sub-commands. Finally, your computer executes the DOS commands in your AUTOEXEC.BAT - commands you would like issued every time you start up your computer.

Most users have their systems boot to the DOS prompt. Some have their systems load shell programs, overlays that dress up your DOS with niceties like help screens, directory trees, and pop-up, drop-down and scrolling menus. Some users have their systems load complete environments like Microsoft's Windows or OS/2.

Whatever you have your system booting to, it is wise to have a good understanding of the fundamental DOS commands available at the DOS prompt. While not always pretty, these commands are both effective and efficient, and can be trusted to perform their individual tasks. If you do ever find yourself working on someone else's computer, DOS is always available below any program or shell running. (At least you'll have some solid ground to stand on.)

Booting from a power-off condition is descriptively called a cold boot. If the machine has been on (is warm) and you reset it, or you use CTRL-ALT-DEL to re-boot, this is called a warm boot.

When booting, your system will look to your A: drive first, to see if the operating system can be loaded from there. Should your hard drive fail, you can use a system disk to boot from A:. (If your system won't boot, or if you have problems operating normally, a floppy disk loaded in your A: drive may be the cause.)


This small text file contains configuration statements for your particular machine. This file must reside in your root directory, to be found as your system boots.

Commonly used statements in configuring a system are;


This statement determines how often your system will look to see if you are trying to break out of a running program by hitting CTRL-C or CTRL-BREAK.

BUFFERS = 20 (or any number from 1 to 99)

This statement declares how much RAM space is to be set aside for information passing to and from disks. The more memory given to this function, the less RAM memory available for your program files.

FILES = 30 (or any number up to 999)

Most major programs need to have anywhere from ten to sixty files open at any given time. Allow installation programs that change this statement automatically to do so, to insure this number is large enough for normal operation of these programs.

DEVICE = C:\DOS\ANSI.SYS (or the name and path of some other device driver to load)

Many programs use special device drivers to control your system's operations in ways not available in DOS. Usually these drivers reside in your root directory and have the extension .SYS (system). Often the drivers themselves need to have their switches set through the addition of definitive parameters in the command line.

To have the contents of the CONFIG.SYS file displayed, "type" it.



FILES = 60






It pays to know what's in your CONFIG.SYS file as most of the commands included here will directly (and sometimes adversely) affect your system's performance. It would be wise to enter a few informative comments as REM(ark) lines in this file, so others can tell why any given statement is there. You can edit this file with any text file editor. But if you do edit this file, any changes you might make will not be recognized until you boot your system again.

Keep a backup copy of your CONFIG.SYS file in your DOS directory, in case you accidently lose (erase) yours.


Once your system boots, DOS will look for the file named AUTOEXEC.BAT in your root directory. This file will be EXECuted AUTOmatically if found, and is generally used to run certain programs that you prescribe to further configure your system and to start up the application you usually run first. This file is a convenience: without this file, your system will simply boot to the inherent C: prompt.

You can use your AUTOEXEC.BAT to clear the screen of left-over driver information, to load TSR programs, to pull up a menu program of some kind, or to execute any legitimate command as you would do from the DOS prompt. To have the contents of the AUTOEXEC.BAT file displayed, "type" it.











This example loads/runs two Norton Utilities programs, then loads a TSR called Sidekick, then establishes a file search path for DOS, sets the environment variable TEMP, runs the internal command PROMPT (to select the user's preference for a DOS prompt), clears the screen with CLS, and finally, runs a program (or batch file) called MENU.

You can edit your AUTOEXEC.BAT file with any text file editor. Any legitimate DOS command line can be included in this file, and there is no limitation on how many command lines you may include.

If you have allowed self-installing programs to edit your AUTOEXEC.BAT, you may find that these programs have taken the best memory and the best PATH position for themselves. You can edit what these programs have put there until you are happy with the priorities and memory allocations.

There is an optimum order to the execution of all the commands you wish executed, but each computer is different, so you'll have to do some experimenting to find what's best for you.

Keep a copy of this file in your DOS directory. If you accidently lose (erase) it, you might spend a very long time trying to remember exactly what was in this file, and your system may never be the same again.

Internal commands...

COMMAND.COM is the file in which the internal DOS commands reside. This file is invoked immediately after your ROM is activated and your operating system has been loaded. It is this ever-present programming that accepts the internal commands entered by you from the DOS prompt, interprets them, and performs the appropriate action.

COMMAND.COM's built-in routines are useful for doing everyday things, like displaying the contents of a file or directory, copying files, and setting the time and date. The most useful internal commands are;

CLS (clear screen)

Entering CLS at the DOS prompt will clear the screen and leave you at a new DOS prompt at the top of the screen.

DATE [date string] (set date for operations)

The DATE command is used to enter a date (usually the current date) into the system for internal use. If you type DATE followed by a legimate date at the DOS prompt, the new date you have entered will overwrite whatever date is in memory. If you simply enter DATE, you will be prompted for a legitimate date.

TIME [time string] (set time for operations)

The TIME command works in exactly the same way as the DATE command - but with the time of day.

PATH [path name(s)] (your search path, in order)

On request, DOS will look for files in directories outside the one you are in, if you establish a path for searches with the PATH command. A good path will allow you to cut down on the amount of typing required to issue some commands, and will allow you to simplify these commands as well. The path in the example below causes DOS to search for files outside the default directory, first in the BATS directory, then in the DOS directory, and finally in the UTIL directory. A semicolon is used to separate the different sub-statements.



The first path in your path statement should be the path of the files you call most often. DOS searches for files you call in the left-to-right order of your path statement. DOS can take a long time to find a file kept in the last location of your path.

PROMPT [$P] [$D] [$T] (select your DOS prompt)

When idle, DOS displays what is referred to as the DOS prompt. Left to its own devices, your prompt would consist only of your current drive designation letter, C:. This is helpful, but can be made more so with the issuance of the PROMPT command with the $P parameter. The command issued below will give you the path (where you are) on the drive, as well as the drive designation for your DOS prompt.




This is by far the most useful of the available parameters for this command. If you like though, $D will give you the date as part of the prompt, and $T will give you the time. If you use more than one parameter to select your prompt, enter them in a series, like this : PROMPT $D $T $P (results in this prompt : C:\08/24/9210:00:00am\)

SET [variable name = variable substance] (establish an environmental variable)

Some programs can accept information from what is known as the working environment. You can use the SET command is to establish, say, a common directory for the temporary files often created by major programs. SET commands are usually the first commands found in the AUTOEXEC.BAT file.


This command, coupled with a configuration instruction issued to a program that makes such temporary files, would direct a program to create these files in your GARBAGE directory. If any are abandoned there, you can easily find them to delete them.

DIR [path] [file name] [/W] [/P] (display directory)

DIR lists the directory and filenames that are readable from where you have issued this command. DIR /W yields a wide display of directory and file names only.


Volume in drive C is MAGGIE

Volume Serial Number is 18A6-50B7

Directory of C:\

BATS <DIR> 05-07-92 9:30a

DB4 <DIR> 05-07-92 9:14a

DOS <DIR> 05-06-92 10:05a

FASTBACK <DIR> 07-16-92 12:50p

UTIL <DIR> 05-07-92 7:37a

COMMAND COM 47845 11-11-91 5:00a

CONFIG SYS 213 06-01-92 7:12a

MOUSE SYS 14153 02-22-91 4:56p

ANSI SYS 2826 04-26-91 3:10p

AUTOEXEC BAT 219 08-13-92 9:02p

10 file(s) 75256 bytes

10973452 bytes free




Volume in drive C is MAGGIE

Volume Serial Number is 18A6-50B7

Directory of C:\



10 file(s) 75256 bytes

10973452 bytes free


When using the DIR command, the /P parameter can be used to pause a long list of files before the list runs off the screen. Issuing this command will cause managable one-screen chunks to be displayed, with a prompt to hit any key to continue.

VOL [drive] (view the volume label of a disk)

You can see the label (and serial number) on any disk by running the DIR command at the disk. You can also use VOL to see this information.


Volume in drive C is MAGGIE

Volume Serial Number is 18A6-50B7


VER (display DOS version)

Use the VER command to determine the DOS version of any computer. No parameters required.


MS-DOS Version 5.0


MD [path] [directory name] (make a directory)

Making sub-directories is done simply by entering MD at the DOS prompt, followed by a legitimate directory name. To make a sub-directory of the directory you are presently in, you need enter only the command and the new directory's name. To make a sub-directory of a directory you are not in, add the path to the name of the new directory.




RD [path] [directory name] (remove a directory)

Use the RD command to remove unwanted directories.






Directories cannot be removed until they are empty of all files and sub-directories. Hence, you may need to use the DEL command to remove any files before you can use the RD command to remove the directories. You must also be "outside" the directory you wish to remove, or it will not be removed.

CD [path] [directory name] (change directory)

The CD command allows you to "position yourself" in another directory, with your new "position" becoming the default directory. Entering CD DOS would put you into the DOS directory. Entering CD\ will take you back out to the root directory. Entering CD.. will take you back one directory, if you are far along into a directory tree. The parameter you enter after the CD command must include a drive specification - CD C:\UTIL - if the directory you would like to be "in" is not directly in line with the one you wish to leave. To cut down on thoughtless errors and on the amount of typing necessary to enter a command line, it sometimes pays to put yourself in the directory that contains the files you wish to manipulate.

TYPE [path] [file name] (display a file)

This simple command will send the contents of any file to your screen for display. This command is useful for viewing text files, but command files and many data files will appear as gibberish, with little on the screen to tell you about their contents or origin.











The TYPE command does not accept wildcard substitutions.

REN [path] [filename] (rename a file)

Use REN to rename files. In the example below, a letter named INQUIRY is renamed to be INQUIRY.LET, to conform to a file name standard.



Wildcards are acceptable, if you wish to rename a group of files with one command.

COPY [path] [filename] [new path] [new file name] [ /V] (typically to copy a file to another location)

To copy files from one location to another, or to duplicate files by making copies with other names, use the COPY command. Here is the command line to copy your CONFIG.SYS file to a backup copy of it in the DOS sub-directory.


1 file(s) copied


You may copy files to any legitimately-named directory on any legitimate drive. Wildcards can be used to copy groups of files with similar names. If you do not specify a destination file name, DOS will use the source file name.








6 file(s) copied


COPY will not prompt you with any overwrite warning. Files are simply copied overtop any file with the same (destination) name.

A good way to make backups of your work files is to make DOS copies of them in another directory on your hard disk or off your computer altogether, and onto a floppy diskette. DOS copies are quick and easy to do, and do not require a special program or advanced abilities to backup and restore your files. (This would be considered the least you should do to secure your data from loss.)

The COPY command also has some unusual uses in copying files to devices, and from devices to files. The most common use of the COPY command involving a device is the copying of short batch file text from the console.





In this example, the batch file for making files READ/WRITE is created by entering the command line to first create the file, then entering the command line (or lines) to be inside the batch file, then ^Z to close and save. There are no messages from DOS to help you, and there is no going back up to re-type anything you have entered, but this is a lot quicker than using a text editor to do the same job. (If you do make a mistake, simply re-do it.)

Here is an example of copying a text file to the parallel printer port LPT1.


1 file(s) copied.


You can also use COPY to join two text files together, into a third file (or into a file with one of the source file's names).




1 file(s) copied.


Finally, you can use the /V option to verify the copying you have done was successful, although this parameter is usually not necessary.

DOS pretty much lets you do any file moving or any file re-naming you choose to, without any warning prompts about potential conflicts or data loss. It's up to you to keep the over-writing of a file or its accidental deletion from happening. By being mindful of the correct syntax for each command you issue, and by using an orderly set of file names, you can keep yourself out of most trouble.

DEL [path] [filename] (delete a file)

To delete a file, use the DEL command. Issue the command from the DOS prompt, followed by the complete file name of the file you wish to delete.



The DEL command accepts file names that include wildcard substitutions.

It may be wise to create a directory for files you wish to be rid of, but are not sure what they are. Create a directory named GARBAGE and move unwanted files to it, instead of deleting them outright. If the files are not called for after some period of time, you can then delete them safely.

The data of a deleted file is not destroyed until it is overwritten by some other file being stored. Only the directory entry is changed - the first letter is replaced with a question mark, and, DOS considers the file deleted.

There are utilities available that can recover the data from deleted files if they have not yet been overwritten. If you are using DOS 5.0, you can use the UNERASE command to recover such data, otherwise, you can use one of Peter Norton's disk management utilities to do so.

External commands...

Primarily because of their size, some commands are not loaded intrinsically with COMMAND.COM, but exist as independent command files. Conventionally, these external commands are kept in their own sub-directory (called DOS). You may need to include the path with the file name when you issue these commands from the DOS prompt.

[path] ATTRIB [+R or -R] [path] [filename] (declare read-write status of files)

To mark files as READ ONLY, or to make READ ONLY files accessible as READ/WRITE, use the ATTRIB command. Use +R as your parameter to make your files READ ONLY and -R to make them READ/WRITE. As an example...



Here are the contents of two one-line batch files that can make issuing this command more convenient (viewed by "typing" the files).






To use these batch files, enter RO [path] filename (or RW [path] filename) at the DOS prompt. Wildcards are permissible.

[path] TREE [drive] [directory] [/F] (display the directory structure of a disk)

To get an overview of your directory structure, use the TREE command.


Directory PATH listing for Volume MAGGIE

Volume Serial Number is 18A6-50B7







^C (^C interrupts the display)


To include file names in the tree structure, include the /F parameter in your command line.


Directory PATH listing for Volume MAGGIE

Volume Serial Number is 18A6-50B7






| ____BATS

|___ PAC.BAT



[path] PRINT [path] [file name] [T] (print a file)

Text files can be printed with this DOS command. PRINT.COM works in the background, printing files while you perform other tasks. Several files can be queued up for printing, and all will print in their turn. A form feed is issued at the end of each file.


Name of list device [PRN]:LPT1

Resident part of PRINT installed

File is being printed


Wildcards in the file names are acceptable. To terminate the printing of a file (or files) use the /T parameter. To see which files are in the queue, enter PRINT without any parameters. To add more files to the print queue, re-issue the command with additional file names.

While printing in the background is desirable, printing anything other than pure text files from DOS is a problem. For files created by word processors that embed font information and printing commands in your work, you will still have to use the programs that created these files to print them.

[path] CHKDSK [drive] [/F] [/V] check the integrity of the data on a disk)

Running CHKDSK is an important part of your disk maintenance routine. CHKDSK can be used to check your directories and file allocation (FAT) table for errors, check your disk space for the fragmented remains of abandoned files, and report on the disk status and space available.


Volume MAGGIE created 07-01-1992 12:06p

Volume Serial Number is 18A6-50B7

85018624 bytes total disk space

81920 bytes in 5 hidden files

208896 bytes in 77 directories

84428800 bytes in 2616 user files

299008 bytes available on disk

2048 bytes in each allocation unit

41513 total allocation units on disk

146 available allocation units on disk

655360 total bytes memory

623728 bytes free


Should CHKDSK find any lost clusters of data, you will be prompted to recover this data. Respond yes, and a series of files (FILE0000.CHK, FILE0001.CHK, etc.) will be created in your root directory. Use the TYPE command or a text processor to examine the recovered data. If you don't need what's been recovered, delete these files and recover your disk space.

Virtually all programs can cause your system to lock up occasionally. When they do, there are often temporary files open on your drive that get abandoned. Using CHKDSK regularly (once a week is recommended) can rid your storage area of these hidden chunks of lost data. If you don't, you will be suffering needlessly as your drive takes longer and longer to read and write around this lost data on your drive, and you may find yourself totally out of disk space one day when you really shouldn't be.

Users have been known to power off or to use CTRL-ALT-DEL or CTRL-C to abort programs they have run by mistake or to cut off some long process prematurely. This also results in the generation of abandoned data on your drive. It may also result in the directory or FAT entries for some files becoming corrupt and unreadable. Should this happen, there is a good chance that you can lose your data files altogether (data that can't be found is as good as data that isn't there).

Using these key sequences must be considered a last resort. If your system has locked up, or if you wish to terminate the running of some program, this may warrant calling in the most experienced person available to appraise the situation for potential data loss.

[path] DISKCOPY [drive] [drive] (copy a diskette)

Should you desire a copy of a diskette, use the DISKCOPY command to create one. A disk copy is just that; it is a copy of all the data from one diskette to another, with the source and target diskettes being identical in format, content and space allocation.


Insert SOURCE diskette in drive A:

Press any key to continue . . .

Insert TARGET diskette in drive A:

Press any key to continue...

Copy another diskette Y/N ?N


Sometimes it is vitally important that certain information on a disk be in one special place. An example of this would be an embedded serial number of a licensed program, or some amount of important information laid down (not necessarily as a file, not necessarily in an allocated space) that must be found in that place on the diskette or some part of some program won't run. DISKCOPY may not always work on this kind of protected disk. You might try a disk-copying program like COPYWRITE to copy these.

[path] FORMAT [drive] [/S] (format a disk)

The pattern in which data is stored on your disks is referred to as the disk format. There are several types of formats used by IBM-type DOS. This variety is mostly attributable to improvements in disk media and the precision of the drives themselves; floppy disk capacity has doubled some six times in the past ten years, and the capacity of hard disks has increased twenty fold.

5-1/4" floppies come in 360 kb and 1.2 meg capacities. 360k diskettes can be read in 1.2 meg drives, but 1.2 meg disks can't be read in 360 kb drives. 360 kb diskettes are also known as double density diskettes; 1.2 meg diskettes are high density.

3-1/2" diskettes come in 720 kb and 1.44 meg, and will soon be commonly available in 2.88 meg. 720 kb diskettes can be read in 1.44 meg drives, but 1.44 meg diskettes cannot be read in 720 kb drives. 720 kb diskettes are also known as double density diskettes; 1.44 meg diskettes are high density.

Unless there is a good reason not to, it is best to let disks be formatted automatically with their maximum capacity. (A good reason not to, might be that the computer that is going to have to read the diskette uses different capacity disks.)

To simply format a diskette to its capacity,


Insert new diskette for drive A:

and press ENTER when ready...

Format another? Y/N N


To make a bootable formatted diskette, transfer the operating system over, too. Simply add the /S parameter to your command line.


Insert new diskette for drive A:

and press ENTER when ready...^C

System transferred

Format another? Y/N N


Remember that, if you do transfer the system to your diskette, you will be taking up some 70 to 120 kb of disk space for the system alone. This is not so noticable on disks with a capacity over 1 mb, but it's roughly one-fifth to one-third the useful disk space of a 360 kb diskette!

With anything less than DOS Version 5.0, formatting a diskette effectively destroys any data on that diskette. DOS 5.0, though, has an added command - UNFORMAT - that can restore a diskette re-formatted with DOS 5.0 to its previous format.


Formatting a hard drive should only happen once in its lifetime. Be very careful not to format your hard drive by mistake. DOS does not think for you. DOS will comply with the command FORMAT C: just as well as with the command FORMAT A:.

a helpful hint...

You may wish to rename your FORMAT command with another name (say DOSFMT.COM), and write a one-line batch file with FORMATA.BAT as its name.




This batch file contains the A: parameter with the command line, so DOS formats A: automatically, safely, every time.

[path] SYS [drive]

(copy operating system to a disk)

If you have a formatted diskette that you would like to make bootable, use the SYS command to transfer your operating system to it.


System transferred


[path] LABEL drive [label name]

(edit the volume label of a disk)

Each disk has a reserved place for an eleven-character label. Use the VOL command to view the volume labels on your disks, use LABEL to edit them.


Volume in drive C is MAGGIE

Volume Serial Number is 18A6-50B7

Volume label (11 characters, ENTER for none)? MAGGIE




System masters...

Since all the information your system needs to boot from the hard drive is on your hard drive, you need to have floppy copies of these files to bring up your hard drive, in case your hard drive fails.

Make two bootable floppies for the type of A: drive you have. Put copies of CONFIG.SYS and AUTOEXEC.BAT, any device drivers your system needs to operate, DOS's FDISK, FORMAT, SYS and CHKDSK commands, and copies of the programs you use to back up and restore your files, so you can re-format and re-construct your C: drive in case of damage beyond repair. These are your system masters.

Be sure to test-boot your system from these floppies before you need to.

Backing up your files...

It is so easy to lose important data files! Almost everyone has a horrific story to tell about the days spent re-entering a past year of accounting data or some huge database of client information. Even re-doing the work from a single productive hour can be a real gumption drain.

The reasons for such losses are many. A single hardware failure can cause you to lose all the data on your hard drive. And what would you do if you picked up a (computer) virus and your key files became corrupt or started disappearing altogether? What if the power goes off during a low-level drive cleanup operation? Where would you be if your computer was stolen, or there is a fire? All major disasters...

Then there's the commonplace - how do you get back that super-critical, ultra-unique file you just erased?

Here are some of the things you can do, to take reasonable care of your program and data files...

For your data files...

Use the save file option, that virtually every major program has, to save your work every fifteen minutes or so. If the power goes off, a magnetic copy of your file will be safely stored on disk.

Save copies of your work files in different directories on your hard drive. The copies are easy to make, and, in case of accidental erasure, you will have an exact copy ready at hand as a replacement.

Use the COPY command to copy your work files onto clearly-labelled floppy disks. Keep a set or two with your computer, and another set in some other safe place (off-site). In the case of theft, it is unlikely that anyone would steal your floppy disks. In the case of hard drive failure, your files can be re-copied onto your new or repaired hard drive. In the case of fire, you have the off-site set.

Copy your work files to floppies, using DOS's BACKUP command. BACKUP has an advantage over COPY, in that you can copy your data onto a series of disks without worrying too much about whether the files you have selected will fit or not. This is especially important if you have individual data files that are bigger than a single disk can hold. In this kind of file copying, files are laid down end to end, in a succession that often puts part of a large file in the last space available on one disk, and the remainder of that file in the first space available on the next.

If you wish to, you may acquire a commercial back-up program to use in place of BACKUP. These programs do virtually the same thing as the BACKUP program does, but they allow you to be more selective in the files you restore and back up, and they are capable of doing different kinds of back-ups. One important advantage is the level of file compression that commercial back-up programs achieve. This can mean savings in both time and the number of disks required to complete a given back-up.

Restoring files amounts to reverse-copying files you have backed up - DOS's COPY with source and destination reversed, BACKUP's counterpart RESTORE, or the restore portion of your commercial back-up program.

path] BACKUP [drive] [path] file name destination drive [/S] (backup files)

BACKUP is an external command that resides in your DOS directory. Generally, this command is used to back up a number of related files in one directory, with the option of including files in the immediate sub-directories as well. To back up all the data files in the DB4\PAC sub-directory, along with any files in any immediate sub-directories,

C:\BACKUP C:\DB4\PAC\*.* A: /S

Insert backup diskette 01 in drive A:

WARNING! Files in the target drive

A:\ root directory will be erased

Press any key to continue . . .










Take the message "files in the target drive will be erased" seriously. BACKUP lays down one large file over everything on that disk; any file you may have there is his-tor-ee.

The following command would back up files with the extension .LET in the sub-directory WS\WSFILES...


The BACKUP command will automatically (and conveniently) format any unformatted diskettes you put in during the BACKUP process.

BACKUP is also capable of backing up files based on their date information and whether or not they have changed since the last back-up. While these may be important features to some, it is simpler (though not necessarily quicker) to back up complete directories, whether the files are new or old, or whether they have changed or not. The parameters for these kinds of back-ups would be available in any, more complete, DOS manual.

A helpful hint...

Your DOS command files and your commercial program files do not change very often, so one or two back-ups of these files - done one time - is plenty. If you have purchased your major programs, you will also have the original installation disks (which should be disk-copied for security) to restore files from. And it is really your customization and configuration of these programs you need to secure. If you can identify these particular files, they are all you need to back up regularly.

Your data files, on the other hand, need to be backed up frequently. These files are your creations; sometimes the data in them exists nowhere else in the world. Protect them, in depth, by making numerous back-ups, with any of the procedures covered here.

[path] RESTORE [source path] [destination path] [file name] [/S][/P][/D] (restore files)

The RESTORE command works in conjunction with the BACKUP command. The command line is usually an iteration of the command line used in the BACKUP procedure, but may also be issued to restore only selected files from the list of files backed up. This command line will restore everything in any back-up set inserted in drive A:.

C:\RESTORE A: C:\*.* /S

Insert backup diskette 01 in drive A:

Press any key to continue . . .



Restored files are placed in the directories they were backed up from. (These directories will be re-created, if they no longer exist.)

To restore a file (or files) from the \DB4\PAC directory,


Insert backup diskette 01 in drive A:

Press any key to continue . . .



This single file would be found in the back-up set and restored.

To be prompted before RESTORE overwrites files that have changed since the last back-up, use the /P parameter. To see what files are actually in a given back-up set, use the /D parameter.

C:\RESTORE A: C:\*.* /S /D

Insert backup diskette 01 in drive A:

Press any key to continue . . .









The file names that match the command line will be displayed, but no files will be restored. (Wildcards are readily accepted.)

Helpful hints...

Check how much disk space your files are taking up where they are, to have an idea of how much space they will take up on the disks you are going to copy them to.

Make up numbered series of plain white, clearly-typed labels to put on your backup diskettes. Use good quality diskettes, and keep them in a safe place.

Rehearse the restoration procedures necessary to restore your files. Don't wait until you have to, to learn how.

Your mission...

Here is a series of plain-English steps to help you organize and secure the data on your PC.

First, make two system masters and store them in a safe place. Then, collect your manuals together. You should have a manual for every piece of hardware and software that you own. Reacquaint yourself with the manuals, and put together a list of who you'll need to call, for help or service.

Now, to organize your hard drive :

1) Identify the files you have.

2) Copy historical files off onto floppy disks.

3) Delete any unwanted or unneeded files.

4) Organize the remaining files and directories.

5) Alpha-sort the file names.

6) Make back-ups of your files.

7) Optimize your hard drive.

To maintain your floppy diskette library :

1) Disk-copy any original-source diskettes.

2) Arrange your diskettes in ordered storage cases.

3) Uniformly label all diskettes (try Avery's #AL-100M).

Routinely :

1) Organize your hard drive.

2) Maintain your floppy diskette library.

3) Clean the outside surfaces of all your hardware.

4) Use a drive-cleaning kit to clean your floppy drives.

5) Maintain a stock of blank diskettes for your drives.

6) Keep all your manuals close-at-hand for reference.

7) Check your help and service list for any changes.

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