The memory used to run programs is referred to as Random Access Memory, or RAM for short.
There are several different types of disk you can use: hard disks, diskettes (floppy disks), and memory (or virtual) disks. The following sections give brief descriptions of these types of disk.
There is another type of disk called a removable disk. Examples of these are Syquest* and Bernoulli* drives.
Always handle diskettes with care.
The write-protect notch on 3.5-inch diskettes is built into the diskette. To write-protect the diskette, slide the plastic tab up so that a hole appears through the write-protect notch.
Write-protect a 5.25-inch diskette by placing a tab (usually supplied with the diskette) over the notch in the top right-hand side of the diskette. The diskette is write-protected until the tab is removed. Some 5.25-inch diskettes do not have a notch; these diskettes are permanently write-protected.
A memory disk only stores data temporarily. When you switch off your computer, or reboot, any data stored in a memory disk is lost. You must use a hard disk or diskettes to store data permanently.
If the hard disk manufacturer has already prepared the disk, you do not need to do it yourself. The operating system installation program detects whether your hard disk has been prepared, and gives you appropriate instructions if the hard disk is not prepared. Refer to Appendix B, ``Preparing the Hard Disk'' in DOSBook for more information.
You may also need to format diskettes before using them. Formatting divides the diskette into sections so that the operating system can store and retrieve data on the diskette. Use the FORMAT command to do this; refer to the ``Command Reference'' chapter of DOSBook for more information on FORMAT.
The Caldera DR-DOS command set includes four different types of command: internal, external, batch file commands, and configuration commands.
The following sections describe the different types of command and how to use them.
PATH is an internal command that enables the operating system to locate external commands. Refer to the ``Command Reference'' chapter of DOSBook for a detailed description of PATH.
The operating system provides a special set of commands to use in batch files. These batch file commands are stored the same way as internal commands, except the CHOICE command. Refer to Chapter 7, ``Batch Processing'' in DOSBook for further information.
If the operating system is installed on a hard disk, the default system prompt appears as follows:
[DRDOS] C:\>This indicates that C: is the current drive. When you enter a command, the operating system always looks to the current drive. If you have installed the operating system onto diskettes, then A:\> is shown as the current drive in the system prompt.
After typing the command line, you must always press <Enter> to make the operating system carry out the instructions.
Command names are up to eight characters in length and are usually followed by options that modify the way the operating system carries out the command. For example:
DIR C:\LETTERS /2Command options such as C:\LETTERS are known as parameters. The parameter C:\LETTERS tells the DIR command which directory's files to list. Command options with a forward slash (/) are referred to as switches. You use a switch to select a particular version of the command. The switch /2, for example, tells DIR to display the directory listing in two columns.
Punctuation is usually required to separate command names from their associated options. In general, you include a space between the command name and the options and a space between each option. You must have a space between parameters, and between parameters and switches, but you can type several switches without using a space between them. For example:
DEL C:\LETTERS\MAYLET.TXT /CSSometimes, other symbols are required, such as commas and colons. The MODE command, for example, looks as follows:
MODE COM1:9600,N,8,1The ``Command Reference'' chapter of DOSBook includes the complete syntax for every operating system command as well as an explanation of the syntax.
Command or filename not recognizedYou may have simply mistyped the instruction or directed the command to the wrong drive (see ``Changing Drives'' below). If you make a mistake and you have not yet pressed <Enter>, you can correct the command line by pressing the <Backspace> key which erases the command line one character at a time. You can then type the command line again.
The operating system also has a powerful feature that stores commands
entered previously and lets you recall them by pressing the up and down
arrow keys. You can then edit and issue them again. You may have enabled
this feature when you installed the operating system by setting the HISTORY
option to ON. If you did not enable HISTORY, you can enable it at any time
by running the SETUP program; see Chapter 9,
``Configuring the System'' in DOSBook for detailed information about using SETUP
and the HISTORY option.
When you enter a command, the operating system always looks for that
command on the current disk drive. If you want a command to operate on
another drive, you change drives by entering the new drive letter followed
by a colon. For example:
This changes the current drive to drive A: and the default prompt changes
Any command you enter now operates on the A: drive.
Getting Online Help for Commands
You can display help text about any command and its options by entering
the command followed by /? or /H.
DOSBOOK command <Enter>
Displaying a Screenful of Data at a Time
Some commands display information that fills more than one screen; text
moves off the screen (scrolls) so that you miss the first part
of the information. This will happen if you enter a DIR command and the
listing is very long, for example. You can suspend scrolling in any of
the following ways:
Every file has a name to identify it and (optionally) an extension. A filename extension is separated from the filename by a period (.) and often identifies the class of the file: LETTER.TXT, for example.
Directories are a means of keeping track of your files by organizing them into groups according to contents, project names, user names, classes, and so on. Directories contain information about the files they have stored in them, including file size, time of creation, and when they were last changed. Directories can be arranged in a hierarchical structure so that they can contain other directories (subdirectories) as well as files. A directory can also have an extension to its name, but extensions to directory names are not used frequently.
The following special characters are not valid:
< > = , ; : . * ? [ ] / \ + |
Also note that the operating system uses special names to identify peripheral devices added to your computer called ``reserved device names.'' You should not name your files with any of these. There are also some common filename extensions that are used for particular types of files; refer to Table 4-1.
Reserved Device Name|
Reserved Filename Extension|
AUX or COMn|
PRN or LPT1|
Copies one or more files between disks, directories, and files.|
Lists the files in the current directory.|
Moves one or more files between disks and directories.|
DEL, ERA, DELQ, ERAQ|
Deletes one or more files. DELQ and ERAQ prompt you before deleting each file.|
Displays the contents of a text file on the screen.|
Changes the name of one or more files.|
Sends a file to a printer if one is connected to your computer.|
CHAPTER?.DOC matches with CHAPTER1.DOC and CHAPTER2.DOC
Therefore, you can use a single command to copy both of these files, by
using the ? wildcard in the command line.
The * Wildcard
The asterisk (*) is ``shorthand'' for several question marks. The
asterisk is valid from the position in which it appears to the end of
the filename. The following example shows this:
and with CHAPMEM.FAX and CHAPFAX.BAK
WARNING: Be careful when you use wildcards. The wildcard *.*, the global
wildcard, includes all files. Typing DEL *.* would delete all
files in a directory. If you use the global wildcard, the operating
system prompts you before executing the command. If you want prompting
before you delete any files, use DELQ and ERAQ.
A filelist is a text file that contains a list of filenames. When you use
a filelist at the system prompt, the filelist name is preceded by the @ (at) symbol. This
tells the command that the file immediately following the @ is a filelist, and to execute
on each file named in the filelist.
Then, when you perform an operation on @MYFILE.LST such as copying it,
FRED.BAT, BERT.BAT, and all files in the current directory with
extension .DAT are copied.
The following is a list of concepts that you need to understand to make
the most of the operating system's directory structure:
You can move around the directory structure from the root downwards, and up to the root again. You can also go directly to a subdirectory without going through intervening directories. Use the CHDIR (or CD) command to move around the directory structure; refer to the ``Command Reference'' chapter of DOSBook for a description of CHDIR (CD).
. means the name of the current directory.
These entries are automatically created by the operating system when you
make a directory. When you issue a DIR command, the entries . and .. appear
at the top of the listing. You cannot delete the . and .. entries in a
In a tree directory structure, more than one file or directory can have the
same name. For example, both the directories SALES and ACCOUNTS can contain
a file called FRANCE.DOC. The operating system distinguishes between the
two files called FRANCE.DOC by using a path. The path shows the operating
system the route through the directory structure to the files.
Working with Directories
There are five commands that are used specifically with directories. They
are listed in Table 4-3.
Lists all the directories on a specified drive.|
Creates a directory.|
Changes your current directory.|
Renames a directory.|
Deletes an empty directory.|
DIR > MYLIST.DOC <Enter>
You can also redirect the output from a command to a device, using the device name. The following command, for example, sends the current directory listing to the first parallel printer:
DIR > PRN <Enter>
The following command, for example, sorts the contents of the file TELNUMS.DOC into alphabetical order:
SORT < TELNUMS.DOC <Enter>
DIR | MORE <Enter>MORE displays the listing one screenful at a time.
MORE is a special type of command, known as a filter command. Filter commands read input, act upon it and then output the result, often to the screen. The common filter commands are MORE, SORT, and FIND.
You can pipe commands through filter commands and combine them with redirection.
Refer to Chapter 16, ``Redirecting Information'' in DOSBook for more information on redirection.