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Chapter 2.
Special Terms and Features in X-DOS
This chapter will familiarize you with the terminology used in
this manual and introduce you to the basic rules of DOS usage.
Most of the terms used are standard throughout the computer
industry, but if you have not previously worked with computers,
many of the terms in this manual will be new to you. Users that
are already acquainted with other disk operating systems for
personal computers should at least browse through this chapter
since it contains information that is unique to X-DOS 5.0.
The Command Line
Whenever you want to issue a X-DOS command or want to run an
application program, you will have to be at the command line. The
command line is also referred to as the X-DOS prompt, since you
will always be prompted for input at the command line. The X-DOS
prompt can easily be customized by the user with the PROMPT
command but the default X-DOS 5.0 prompt appears like this:
A:\DOS|
where A: shows the default disk drive , \DOS shows the default
directory (i.e. path) and | is the prompt delimiter.
The path is shown above the line where you will enter your
commands.
Whenever you see the X-DOS prompt, this means that X-DOS is
waiting for you to enter a command, which can be any X-DOS
command or a command to load an application program.
To run a command, you must type the name of the command and press
the [Enter] key on your keyboard. X-DOS will then try to carry
out the command you have entered. You must always press the
[Enter] key on your keyboard following the name of the command to
carry out any command.
Files and Filenames
To keep track of data, X-DOS stores the data in a file on a
disk(ette) just like a folder in a drawer of a filing cabinet.
Files can contain any kind of information from normal text to
computer understandable information.
To distinguish different files, they must all have a name. A
filename consists of two parts: a name and an extension.
The name usually describes the contents of a file while the
extension is often used to specify the type of file. Here is an
example of a filename:
FILENAME.DOC
2-1
where FILENAME is the name of the file and .DOC is the extension.
The filename and the extension together are often referred to as
the filespec. You can enter a filename in either upper or lower-
case since X-DOS does not distinguish case for filenames. The
name part of a filename must always be present and it can consist
of from one to eight characters.
The extension is optional except for program files that must have
an extension of either .EXE or .COM and .BAT extension.
It is normally a good idea to include the extension as part of
the filespec to describe the type of file, like .DOC or .TXT for
text files. The extension can be up to three characters long and
must always be preceded by a period (.).
The following characters can be used in both the name part and
the extension of X-DOS filespecs:
* All letters in both upper and lower-case from A to Z
* All digits from 0 to 9.
* The following special characters: ! @ # $ % & ( ) - { } '
Even though X-DOS lets you use special characters in filenames,
you should normally try to avoid using these characters unless
you have a good reason to do so.
Directories
To organize your files into groups of related files, X-DOS 5.0
lets you create directories. A directory is an area on a disk or
diskette which contains information concerning the files related
to that directory such as the filename, the file size, and the
last modification date for each file. A directory can be compared
to a drawer in a filing cabinet, containing folders of related
data.
If you do not use directories to organize your files, you will
probably soon experience problems keeping track of your different
files.
There are also certain limitations to how many files you can
store in the main directory of a disk, which is called the root
directory.
The root directory is automatically created when a disk(ette) is
formatted and must always be present on a disk(ette). You can
create directories in the root directory, you can create sub-
directories in a directory of the root directory, and so on.
Directories below the root directory are called sub-directories.
You can create sub-directories many levels deep but you should
try to keep the number of levels in your directory structure to
as few levels of sub-directories as possible or it may otherwise
be very difficult to keep an overview of your directory
structure.
2-2
The naming convention of directories follows that of filenames.
You can have a directory name of from one to eight characters and
an optional directory extension of up to three characters.
Extensions on directory names are seldom used since the name
normally is enough to describe the contents of the directory.
The directory you are currently residing in is called the default
directory. You will have a default (current) directory for each
of your drives.
A directory one level above the default directory is called the
parent directory and any sub-directories to the default directory
are called child directories.
When you display the contents of a directory you have to be able
to distinguish between files and sub-directories in the directory
you are displaying the contents of.
When you display the contents of a directory other than the root
directory you will probably notice that the directory seems to
contain two directories which are named `.' and `..'.
These two directory entries are available in all directories
except for the root directory. The `.' entry is a substitution
character for the default directory and the `..' entry is a
substitution character for the parent directory.
Here is an example on how you can use these substitution entries.
Let us for a moment assume that your default directory is
C:\PROGRAMS\WORDPROC and you want to display the contents of the
C:\PROGRAMS directory with the DIR command. Normally, you will
have to type:
DIR C:\PROGRAMS
Since the C:\PROGRAMS directory is the parent directory to the
C:\PROGRAMS\WORDPROC directory you can save a lot of typing by
using the parent substitution entry `..' instead of specifying
the directory path.
By doing so you can display the contents of the C:\PROGRAMS
directory just by typing:
DIR ..
The Path
The path in X-DOS is like a road map through directories,
describing how to get to your files.
PATH is an X-DOS command but is also used to describe a range of
2-3
successive directories to reach a specific file. Look at the
following example.
You have a file by the filename EXAMPLE.COM stored in a sub-
directory of the root directory called PROGRAMS.
If the default directory is the root directory then you can
specify the road to the EXAMPLE.COM file like this:
PROGRAMS\EXAMPLE.COM
where PROGRAMS\ is the path to the file EXAMPLE.COM. Since
EXAMPLE.COM is an executable file, you could type the above line
followed by [Enter] to run the program. If you want to be able
to reach EXAMPLE.COM from anywhere on the drive, you only have to
precede the previous example with a backslash (\) like this:
\PROGRAMS\EXAMPLE.COM
This tells X-DOS to start looking for the PROGRAMS directory from
the root (\) directory of the default drive, no matter what the
default directory is.
This can be expanded even further since you might not be on the
same drive as the EXAMPLE.COM file. To reach the EXAMPLE.COM
program from anywhere on your disk drives you should type:
d:\PROGRAMS\EXAMPLE.COM
where d: can be any valid drive specification, such as the A:
drive.
If the file EXAMPLE.COM resided in a sub-directory of a sub-
directory, it could get rather tedious to execute the program
since you would either have to be in the same directory as the
file or you would have to issue a lengthy path along with the
filename.
To avoid this, X-DOS lets you specify a path with the PATH and
ADDPATH commands. In this path, you can insert the route to the
directories you want X-DOS to search through when you want to run
a program.
To avoid having to type a lengthy path every time you boot your
computer, insert the PATH command with your preferred range of
directory paths in the AUTOEXEC.BAT file. The AUTOEXEC.BAT file
is a configuration file that is automatically executed every time
you reboot your computer.
You will probably want to include a path to all of the
directories which contains executable files that you often use.
If you temporarily want to append a path to a directory which is
not normally included in your PATH statement, you can use the
ADDPATH command to add this path to the end of your current path.
2-4
Memory
You need Memory (also called RAM or Random Access Memory) in your
computer to be able to run any kind of program.
Whenever you want to issue an X-DOS command or run an application
program, it must first be loaded into memory before your computer
can execute it. Even when you boot your computer, X-DOS 5.0
takes up some memory by placing some of its system files
permanently in your memory.
There are different kinds of memory; conventional (base) memory,
extended memory, and expanded memory.
The conventional memory on a personal computer is the memory
used by programs to execute from within and can be no larger than
640K.
This is due to the design of the early versions of IBM's personal
computers and limitations of the Intel 8088 microprocessor, the
chosen microprocessor for these personal computers.
Today many personal computers are shipped with more memory than
640K as a standard. The memory above 1MB is normally what is
called extended memory. The third kind of memory, expanded
memory, is often referred to as EMS or LIM memory. This kind of
memory will let you run large programs that would otherwise not
be able to run or would run inefficiently in conventional memory.
To be able to use expanded memory with a program, the program
must be specifically designed to take advantage of expanded
memory.
You will normally have to get a special memory expansion card to
acquire this type of memory but more and more personal computers
are shipped with utilities that allow you to transform extended
memory into expanded memory such as the VRAM/386 program included
in the Professional X-DOS diskette.
The virtual disk manager (VDISK.SYS) in X-DOS lets you create a
virtual disk in expanded memory or extended memory.
Another kind of memory is ROM (Read Only Memory). All PCs have
ROM and this usually contains the BIOS (Basic Input Output
System) which is firmware that ensures your PC is compatible with
the industry standard. The X-DOS operating system can also be
stored in ROM depending on the design of the PC being used.
File Types in X-DOS
In this section you will learn about the different file and
program types that X-DOS 5.0 uses and recognizes.
The System Files
2-5
X-DOS 5.0 has three system files called X-DOS.SYS, ]COMMAND.COM,
and MAX.COM. Two of these, X-DOS.SYS and COMMAND.COM, are
essential for X-DOS and must always be present for X-DOS to work.
The third system file, MAX.COM, is the second command processor
and is not essential for running X-DOS 5.0, although the absence
of this file greatly reduces the number of commands available in
X-DOS.
The X-DOS.SYS file must always be in the root directory of your
boot drive. It is a Hidden file which means that you will not
normally be able to see it when you list the contents of the root
directory.
COMMAND.COM and MAX.COM are Read-Only files which means that you
will not be able to accidentally overwrite these files.
Executable Files
Any files with an extension of .COM, .EXE or .BAT are treated by
X-DOS as executable files. You can always run an executable file
by typing its name at the command line followed by pressing the
[Enter] key.
When you run a program, you do not need to type the extension
since X-DOS automatically looks for a file with one of the three
extensions above.
All of X-DOS's external commands have an extension of .COM or
.EXE as do all application programs. If you try to execute a
file with a different extension than the three listed above, X-
DOS will display an error message.
The CONFIG.SYS File
You can use the configuration file CONFIG.SYS to customize X-DOS
to your needs. The CONFIG.SYS file is an ASCII text file and is
used by the system files to install X-DOS during start-up
according to the contents placed in it.
If you have a CONFIG.SYS file, it must always be present in the
root directory on your boot disk(ette) or X-DOS will not be able
to find it.
Device Drivers
Excluding CONFIG.SYS, files ending with .SYS and sometimes .BIN
are device drivers and are normally related to the hardware
configuration of your computer. To install a device driver you
must list it in the CONFIG.SYS file.
Internal Commands
Internal commands are X-DOS commands that are inside either one
of the two command processors COMMAND.COM or MAX.COM. You will
not be able to see an internal command if you list the contents
of your disk(ette) but you can still execute them the same as
executable files.
2-6
Since some internal commands are already in memory, they will
execute very fast and you can call them from anywhere on your
disk.
X-DOS has more than 80 internal commands. DIR, CLS, CD, and MD
are examples of internal commands.
External Commands
External commands are X-DOS commands located on your disk(ette)
with either an extension of .EXE or .COM. It is important for you
to make sure that X-DOS can find its external commands when you
need them.
As a default, X-DOS assumes that they are in a \DOS directory on
your boot disk(ette). You can change this by using the PATH
command to look for executable files in other directories.
CHKDSK.COM, DEBUG.COM, FORMAT.COM, ED.EXE, and SETUP.COM are
examples of external X-DOS commands.
Batch Files
Files with a .BAT file extension are batch files and are
sometimes referred to as command scripts and are essentially
plain text (ASCII) files.
In batch files you can list any commands or programs you want to
run, line by line, and X-DOS will process each line one at a
time. This allows you to link a series of commands and programs
to one filename.
During boot-up X-DOS always looks for one specific batch file
called AUTOEXEC.BAT which is executed if it exists. Insert any
statements in this file that you want to run every time you boot
your computer.
Application Programs
An application program refers to any program like a word
processor, a database, a spreadsheet, and so on. As a guideline,
application programs are often large programs consisting of
multiple files. Wordstar and Lotus 1-2-3 are examples of
application programs.
Error Messages
The X-DOS operating system uses error messages to tell you when
it encounters a problem while processing a X-DOS command or any
other program.
Probably the most common error message you are going to see is:
Specified filename invalid
This error message tells you that X-DOS could not find the
command or program name that you just tried to execute. You
either typed it incorrectly or X-DOS was not able to find it on
2-7
the specified path.
Another kind of error message requires that you take action
before you can continue. An example is when you try to access a
floppy drive without any diskette or with the floppy drive door
open. In that case you will see the following error message:
Fatal Error occurred on drive A
Operation was : reading from drive A
Error reported : Drive not ready,
Disk area error : Dos area
You can (A)bort, (R)etry, (F)ail ?
External and Internal Storage Devices
Since all of the information in your computer's memory is lost
when you turn off your computer, you must have some kind of
external storage medium to store your files onto. The most
common external storage media are diskettes and hard disks.
X-DOS references all drives on your computer with a drive letter.
Two letters are reserved for floppy drives; drive A: and drive
B:.
Even if your computer only has one floppy drive, X-DOS still
reserves the drive letter B: for a future floppy drive. Drives
on your hard disk will therefore be designated with a drive
letter beginning from drive C:.
Drives can be referenced from drive A: to drive Z:. Virtual
(RAM) disks are internal storage devices and are also referenced
with drive letters, beginning with the designator after your last
logical drive, if the virtual disk statement follows any
partition manager statement you may have in your CONFIG.SYS
configuration file.
You can make any of the available drives the default (current)
drive by typing the drive letter followed by a colon (:) and
then pressing the [Enter] key. If your default drive is drive C:
and you want to change to drive A:, at the command line you
should type:
A:
Floppy Drives and Diskettes
Virtually all personal computers have one or two floppy drives.
You use floppy drives to store and retrieve data from diskettes.
A diskette is a flexible plastic disk which stores the data
magnetically.
Diskettes come in many formats for personal computers, the most
common of which are: 5 1/4" 360K diskettes, 3 1/2" 720K
diskettes, 5 1/4" 1.2M diskettes and 3 1/2" 1.44M diskettes.
2-8
Hard Disks
Hard disk drives are storage devices of large capacity, normally
mounted inside of a computer. A standard 20M hard disk can store
an amount of data equal to the contents of more than fifty-five
360K diskettes. A hard disk also retrieves and stores data many
times faster than a floppy drive. These features make hard disks
preferable as a storage device. Hard disks comes in sizes of 10M
(the equivalent of 10,000,000 characters) to more than 1,000M
(more than 1,000,000,000 characters) but most hard disks range
between 20M and 80M.
Virtual Disks
X-DOS 5.0 lets you create one or more virtual (RAM) disks in
memory. The reason for using a virtual disk is that the access
time to a virtual disk is extremely fast; many times faster than
a hard disk. You can install virtual disks in conventional
memory, extended memory, and expanded memory with the virtual
disk driver VDISK.SYS.
ROM Disks
If you are using X-DOS 5.0 from ROM, X-DOS will consider your ROM
space as a disk too where one or more files have been stored for
you. Refer to the X-DOS in ROM section to obtain more details.
Wildcard Characters
Two special characters called wildcards can be used in filespecs.
These two characters are the question mark (?) and the asterisk
(*). The wildcards are used in the specification of filenames to
abbreviate the typing of filenames or to specify a range of
files. As a unique feature, X-DOS also allows the use of
wildcards with the CD command.
The `?' wildcard is used in a filespec to replace any one
character in the name or extension part. This way, any character
can fill this place when X-DOS tries to match filenames.
You can use multiple `?' wildcards in the filespec, each of which
takes up the space of one character. Look at the following
example:
DEL LETTER?.T??
The following files will match this filespec and will be deleted
from the default directory.
LETTER1.TXT & LETTER4.TXT & LETTERS.TEX
The following files will not match the LETTER?.T?? specification,
since the `?' wildcard only replaces one character in the
filespec, and they will therefore be left intact:
LETTER10.TXT & LETTERS1.EXT
2-9
The `*' wildcard is used in filespecs to replace a range of
characters. If you use the `*' wildcard in the name part of a
filespec, it will replace the rest of the characters up to the
extension part.
If you have a filespec like LET*.DOC, X-DOS will try to match any
files that have LET as the first three characters and .DOC as an
extension.
Look at the following example:
COPY LETTER*.*
X-DOS will copy all files with LETTER as the first six letters
and any characters as the next two characters of the name part.
The extension can be any valid extension.
An often used wildcard combination is the *.* filespec
specification. X-DOS will treat a specification like this as
concerning all files in a specified directory. This allows you
to easily copy, modify, or delete all files in a directory.
Using Parameters (Options and Switches)
Many of the X-DOS commands use parameters (switches) which modify
the operation of the commands. Some even accept a range of
parameters to tailor the function.
X-DOS command parameters are always preceded with a delimiter,
often a slash (/) or a space.
Command Line Editing
You should fully understand the functions and the power that you
always have readily available from your keyboard to utilize X-DOS
to its optimum.
One of the very powerful features of X-DOS is its ability to let
you save time by allowing you to recall previously executed
commands and edit the current command displayed at the command
line.
Whenever you type a command or recall a previously executed
command, you can always edit any part of it without having to
delete portions of it.
As a default X-DOS sets aside 256 bytes of memory to hold
previously executed commands. This memory is called a history
buffer.
If you wish to increase the amount of memory allocated to the
history buffer, you can insert the HISTORY statement in your
CONFIG.SYS file and specify a value up to 2,048 bytes which
2-10
should hold more than 100 previously executed commands.
You will probably find that the default 256 bytes of memory is
enough.
Command Line Editing keys
The following keys can be used to edit commands at the command
line:
[Up] arrow key Recalls the previously executed
command.
[F3] function key Recalls the previously executed command
the same way as the [Up] arrow
key. This function key is set up
to repeat the previously executed
command for compatibility with the
DOS standard.
[Down] arrow key Recalls the last command in the history
buffer.
[Left] arrow key Moves the cursor one character to the
left in the command which is
currently displayed at the command
line.
[Right] arrow key Moves the cursor one character to the
right in the command which is
currently displayed at the command
line.
[Home] Moves the cursor to the beginning of
the command currently displayed at
the command line.
[End] Moves the cursor to the end of the
command currently displayed at the
command line.
[Ins] Toggles between insert and overwrite
mode when editing commands.
[Del] Deletes the character at the current
cursor position.
[Backspace] Deletes the character to the left of
the cursor.
[Esc] Clears the command line.
[Enter] Executes the command currently
displayed at the command line.
You can execute a command even if
the cursor is in the middle of the
command.
Function Keys
X-DOS allows you great flexibility in the use of function keys by
letting you set up to 39 function key assignments. You will not
be able to redefine the [F3] function key since it is always set
up so it repeats the previously executed command. This option can
only be used if you set the FKEYS=ON switch in the CONFIG.SYS. By
default and to respect compatibility with the DOS standard, this
2-11
switch was set to OFF.
By assigning X-DOS commands or any other program names to
function keys, you only need to press one key to execute X-DOS
commands or programs.
The Default Function Key Assignments
If you choose not to define the function keys, X-DOS
automatically assigns the following ten commands to the ten
function keys [F1] to [F10].
<F1> HELP
<F2> ED
<F3> Cannot be redefined
<F4> DIR
<F5> MAPMEM
<F6> ED
<F7> DISKCOPY A: A:
<F8> TREE
<F9> CHKDSK
<F10> XSHELL
The ten function key assignments can be as long as 20 characters
each. If you want to make permanent changes to the function key
definitions, you can use enter the ALIAS command in your
AUTOEXEC.BAT file.
You can also change function key definitions permanently if you
load the ANSI.SYS screen driver. Please refer to the ANSI.SYS
command description later in this manual.
X-DOS features five other hot keys that can be used to terminate
the execution of programs, reboot the computer, or print the
screen:
[Ctrl]C or [Ctrl][Break] Stops the execution of a batch file or
program.
[Ctrl][Alt][Del] Reboots the computer and loads the
system files again.
[Ctrl]S Temporarily halts scrolling of the
screen. Pressing any key will
continue the scrolling.
[Pause] Many of the newer keyboards feature a
[Pause] key which works like the
[Ctrl]S hot key sequence.
[Shift][PrtSc] prints the contents of the screen to
the default printer.
Quick Keys
A quick key is a highlighted letter within a menu. Quick keys
are only used in those X-DOS commands that feature a full-screen
display with men
