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1992-02-13
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Chapter 5.
Internal Configuration Commands
Introduction
Chapter 4. explained how the AUTOEXEC.BAT and CONFIG.SYS files
can be configured using the install program provided with X-DOS.
The various commands which can be entered into the AUTOEXEC.BAT
and CONFIG.SYS files, called the Internal Configuration Commands,
were briefly introduced to help you decide which of these
commands you should use during installation. In this chapter, a
detailed explanation of the functions of all the internal
configuration commands, and the various parameters and switches
that can be used with these commands, is given.
We suggest that after you have been using X-DOS for a while and
are ready to start taking advantage of the full power offered by
this operating system, you read through this chapter to get a
good understanding of what you can do with the internal
configuration commands. You may then use the install program to
configure these commands in your AUTOEXEC.BAT and CONFIG.SYS
files. Please note that you can also edit the AUTOEXEC.BAT and
CONFIG.SYS files directly using the editor provided with X-DOS.
5-1
The ANSI.SYS Device Driver
Purpose This device driver enables you to use ANSI escape
sequences to extend your control of the screen and
keyboard. ANSI escape sequences are tedious to use
but they can create quite remarkable results when
used properly. You can, for example, totally remap
your keyboard, make fancy command line prompts, and
much more.
Type External Device Driver
Syntax DEVICE=[d:][path]ANSI.SYS [Inserted in your
CONFIG.SYS file
Where d:path - is the drive and path to the directory in
which the ANSI.SYS device driver resides.
5-2
BREAK Configuration Command
Purpose his configuration command is used to set the
circumstances under which [Ctrl]-C and [Ctrl][Break]
are allowed to terminate program execution.
Type Internal Configuration Command
Syntax BREAK [ON | OFF]
Where ON - specifies that BREAK mode will be turned ON.
OFF - specifies that BREAK mode will be turned OFF.
Remarks X-DOS's default setting is BREAK = OFF. Therefore, X-
DOS only checks for a [Ctrl]-C or [Ctrl][Break]
sequence during:
* Standard input functions
* Standard output functions
* Print operations
* Auxiliary operations
To make X-DOS check for [Ctrl]-C and [Ctrl][Break] whenever it is
requested set BREAK = ON in the CONFIG.SYS file.
5-3
BUFFERS Configuration Command
Purpose This configuration command specifies the number of
disk buffers that X-DOS allocates. A larger number
normally increases the speed of disk intensive
applications but also consumes more memory.
Type Internal Configuration Command
Syntax BUFFERS=xx [/E][/A]
Where xx - is the number of buffers that X-DOS will
allocate in memory. The default value for xx is 20
and must be in the range of 5 to 4,095. If you
install X-DOS with the INSTALL command, the default
value is set to 20.
/E - tells X-DOS to put the buffers in extended
memory
/A - tells X-DOS to put the buffers in expanded
memory
Remarks: Please note that the buffers cannot be put in
extended or expanded memory in the evaluation version
of X-DOS.
The Extended Memory allocation requires the XMS
driver loader. Either the internal X-DOS XMS driver
can be used (see below) or any other commercial
product. Please note that though BUFFERS can be put
in extended or expanded memory, some buffers have to
remain in lower memory for DMA transfer.
Examples: If you want to modify the BUFFERS size to 15, you
should load the CONFIG.SYS file into ED and add the
following line:
BUFFERS = 15
5-4
The CACHE Configuration Command
Purpose This configuration command increases the speed of
disk intensive programs. It works best if you have
extended memory or expanded memory available and
normally gives better results than increasing the
number of disk buffers. The cache only works on hard
disks.
Type Internal Configuration Command
Syntax CACHE=/D0 [/D1] [/Mxxxx] [/E] [/A]
Where /D0 - specifies that you want to cache the first
physical disk, including all partitions on that disk.
/D1 - lets you optionally cache a second physical
disk if your computer has two hard disks installed.
/Mxxxx - sets the amount of memory that CACHE will
use for disk caching. You can specify a cache size up
to 8,192K in size. You must enter the cache size in K
(kilobytes). If you do not specify a CACHE size with
the /Mxxxx parameter, CACHE automatically sets up a
64K cache.
/E - sets up a disk cache in extended memory.
/A - sets up a disk cache in expanded memory.
Remarks: Please note that the CACHE command cannot be
activated in the evaluation version of X-DOS.
CACHE uses the memory you allocate for caching to
store data most recently read from the disks.
Additionally, CACHE reads more data into memory than
is actually needed, forecasting which data may be
needed on the following disk access. By doing this,
there is a good possibility that the next data your
program needs to read from the disk is already in the
memory area of your cache. Since reading from memory
is much faster than reading from even the fastest
hard disk, a cache will dramatically improve the
performance of disk intensive programs. The larger
the cache, the better the probability is that the
needed data is already in memory. You can only cache
hard disks. The CACHE statement does not support
caching of removable media.
You must always specify at least one physical drive
to cache or you will get an error message. It is
important that you understand what a physical drive
is. A physical drive refers to a complete hard disk,
including all partitions on that hard disk. If your
computer has one hard disk with three partitions set
5-5
up as drive C:, drive D:, and drive E:, you only need
to specify the /D0 parameter after the CACHE
statement to cache all of the three drives since they
all reside on your first, and only, physical disk. If
your computer has two hard disks installed and you
choose to install a cache for both of them, the total
amount of memory used by CACHE (as specified with the
/Mxxxx parameter) will double.
If you set up a cache for your hard disk(s), you may
want to reduce the number of buffers you have set up
with the BUFFERS statement since CACHE essentially
does the same job as BUFFERS but in a much more
efficient way. By reducing the amount of buffers, you
can save some precious memory. Just keep in mind that
CACHE does not support floppy drives so you should
not set the number of BUFFERS too low since this can
dramatically decrease the performance on floppy
drives.
If you specify more memory for caching than is
available in your system, CACHE will display an error
message and remain un-installed. Since certain
programs such as backup programs may have problems
working with a cache in memory, X-DOS provides a way
of disabling CACHE from the command line. The X-DOS
cache is a write through cache which means that it
will increase the speed of the reading process while
not affecting writing operations.
Examples: If your computer has one hard disk installed and you
want to set up a cache of 2MB in XMS memory for your
hard disk, you should include the following statement
in your CONFIG.SYS configuration file:
CACHE = /D0/M2048/E
5-6
The COUNTRY Configuration Command
Purpose This configuration command sets the time format and
date format for the selected country.
Type Internal Configuration Command
Syntax COUNTRY=xxx
Where xxx - is the international telephone code for your
country.
Remarks: The default value for COUNTRY is 001 which is the
international country code for the United States. The
following list shows the countries supported by X-
DOS:
COUNTRY INT. CODE
Australia 061
Belgium 032
Canada-French 002
Denmark 045
Finland 358
France 033
Germany 049
Italy 039
Israel 972
Middle East 785
Netherlands 031
Norway 047
Portugal 351
Spain 034
Sweden 046
Switzerland 041
United Kingdom 044
United States 001
5-7
The DEVICE Configuration Command
Purpose This configuration command makes X-DOS install device
drivers during start-up.
Type Internal Configuration Command
Syntax DEVICE=[d:][path]filename
Where d:path - is the drive and path to the directory which
contains the device driver you want to install.
filename - is the name of the device driver to
install.
Remarks: Device drivers are normally used to control certain
parts of hardware on your computer. X-DOS supplies
you with three device drivers on the X-DOS disk.
These drivers have the following functions:
ANSI.SYS : is a console driver which can be used to enhance
standard input and output. Since X-DOS already
implements enhancements for standard input and
output, this device driver is normally not required.
VDISK.SYS : is the virtual disk driver which can be used to
install disks in either conventional memory, extended
memory, or expanded memory.
Virtual disks are often referred to as RAM disks and
are a much faster storage media than normal disk
drives. You can set up several virtual disks, each of
which can be a maximum of 16,384K (16 megabytes) in
size. If you purchase certain hardware add-on
products for your computer, you may have to install a
device driver in the CONFIG.SYS file to use this
product.
Just include the name of that particular products
device driver in your CONFIG.SYS file including drive
specification and path and this driver will
automatically be installed the next time you boot
your computer.
Examples: If you want to create a RAM disk in extended memory
with the size 384K and assuming that the VDISK.SYS
device driver is located in the C:\DOS directory then
you should add the following statement on a separate
line in your CONFIG.SYS file.
DEVICE=C:\DOS\VDISK.SYS 384 /E
5-8
5-9
The DOS Configuration Command
Purpose This configuration command will load the kernel of X-
DOS in the High Memory Area.
Type Internal Configuration Command
Syntax DOS=HIGH
Where HIGH - is the parameter for relocating the X-DOS
kernel into HMA
Remarks: Please note that the DOS relocation into HMA is not
provided in the evaluation version of X-DOS.
High Memory Area is only available on 286, 386 and
486 computers. It consists of the first 64K (- 16
bytes) of the extended memory area.
This segment of memory has the particularity of being
in extended memory but still being accessible in real
mode, thus allowing it to be viewed as memory by DOS.
By setting the DOS switch to HIGH, the kernel will
attempt to detect the availability of the HMA and
relocate itself in this portion of memory. It will
leave in the low memory some data used by DOS that
cannot be put in HMA.
Upon activation of the DOS=HIGH switch, X-DOS will
also activate the internal XMS driver, that manages
the rest of the Extended Memory (see below).
5-10
The FCBS Configuration Command
Purpose This configuration command sets the number of files
that the file control blocks can open at one time.
Type Internal Configuration Command
Syntax FCBS=x
Where x - is the number of files that the file control
blocks can open at one time. The default value for x
is 4 and must be in the range of 1 to 255.
Remarks: File control blocks are used to control open files.
Programs that use file control blocks to access files
will have one file control block assigned to each
open file.
File control blocks were originally implemented in
the first version of the MS-DOS operating system for
compatibility with the old CP/M operating system.
Now, programs mostly use the more powerful file
handles to control open files. X-DOS, however,
support file control blocks for compatibility with
older programs.
5-11
The FILES Configuration Command
Purpose This configuration command sets the number of file
handles which can be opened at one time.
Type Internal Configuration Command
Syntax FILES=xxx
Where xxx - is the number of file handles which can be
opened at the same time. The default value for xxx is
20 and must be in the range of 8 to 255.
Remarks: The default setting of FILES = 20 is enough in most
cases but certain programs like accounting programs,
database programs, and desktop publishing programs
often need to be able to open a larger amount of file
handles at the same time. If you encounter an error
message, stating that there are not enough file
handles available, you will have to increase the
number of file handles with the FILES statement in
CONFIG.SYS. You can do this either by using the X-DOS
program INSTALL or by editing the CONFIG.SYS file and
adding the FILES = statement.
Examples: If you want to modify the number of file handles in
the FILES statement to 30, you should load the
CONFIG.SYS file into ED and insert a line with the
following contents:
FILES=30
5-12
The FKEY Configuration Command
Purpose This configuration command is used to turn off the
default X-DOS function key definitions.
Type Internal Configuration Command
Syntax FKEY=ON
Where ON - enables the use of the default function key
definitions and redefinition of function keys from
the command line with the ALIAS command.
Remarks: You can ask X-DOS to assign commands to some of the
function keys and redefine function keys to execute
different commands. You can even combine the [Shift],
[Ctrl], or [Alt] keys with the function keys so you
can define a total of 39 commands to be executed by
the touch of a hot key.
You may wonder why you can only define 39 commands,
not 40 commands. The reason for this is
compatibility. X-DOS does not allow you to redefine
the [F3] function key, which is used by MS-DOS to
recall the previous command.
5-13
The HISTORY Configuration Command
Purpose This configuration command sets the amount of memory
allocated for the command line history buffer. The
history buffer allows you to recall and edit
previously executed commands.
Type Internal Configuration Command
Syntax HISTORY=xxxx
Where xxxx - is the number of bytes which will be allocated
to the history buffer. The default value for xxxx is
256 and must be in the range of 256 to 2,048.
Remarks: The default setting of HISTORY = 256 should be enough
in most cases since this amount of memory can hold
about 15 to 20 previously executed commands.
You can increase the history buffer so it will be
able to hold more than 100 commands. Just keep in
mind that if you have to scroll through dozens of
commands to find a particular command it would
probably be faster to type it again. Also, when you
allocate memory for the history buffer you are using
precious memory which will not be available for
application program.
Examples: If you want to increase the amount of memory
allocated for the history buffer to 512 bytes, you
should load the CONFIG.SYS file into ED and insert a
line with the following contents:
HISTORY = 512
5-14
The LASTDRIVE Configuration Command
Purpose This configuration command sets the last available
drive letter X-DOS can access. You only need to
change this if you plan to use the SUBST command or a
similar utility.
Type Internal Configuration Command
Syntax LASTDRIVE=x
Where x - is a character between A and Z, describing a
drive letter. This drive letter will be the last
available drive that you can access with X-DOS.
Remarks: You can never set LASTDRIVE equal to a drive letter
less than the number of drives that you have
installed in your computer. If you do set the
LASTDRIVE equal to a drive letter less than the
number of installed drives, X-DOS will ignore this
statement in the CONFIG.SYS file.
Examples: If you want to set the number of available drives to
10 which is the drive letter J, you should include
the following command in the CONFIG.SYS file:
LASTDRIVE = J
5-15
The SHELL Configuration Command
Purpose This configuration command sets the name and location
of the primary command processor. It can also be used
to specify the size of the environment of the primary
X-DOS command processor, COMMAND.COM.
Type Internal Configuration Command
Syntax SHELL=[d:][path]COMMAND.COM [/P] [/E:xxxx]
or
SHELL=[d:][path]filename [params]
Where d:path - is the drive and path to the directory in
which the command processor is located.
/P - is a parameter used by COMMAND.COM which makes
the current command processor permanent.
/E:xxxx - is the number of bytes allocated to the
environment of the COMMAND.COM command processor. The
default value for xxxx is 384 and must be in the
range of 160 to 9,999.
filename - is the filename of a new command
processor.
params - are any valid parameters used by the new
command processor.
Remarks: The SHELL command can be used for several purposes
which are split into two main areas; using SHELL with
COMMAND.COM and using SHELL with a new command
processor.
Using the SHELL command with COMMAND.COM allows the
user to copy the COMMAND.COM file to a different
location, i.e. a virtual disk, and tell X-DOS where
to find it. Also, it is often used to set a different
size for the environment. Since X-DOS lets the user
set environment variables for some of its commands,
and many application programs also use the
environment, it may be necessary to use the SHELL
command to extend the environment size.
The second major purpose of the SHELL command is to
install a new command processor which takes over the
job of COMMAND.COM. Note that you can theoretically
replace the X-DOS command processor with a command
processor supplied by another vendor, such as the 4-
5-16
DOS COMMAND.COM from JP Software. However, please
note that such products may not work with the second
command overlay and the SHELL. As such we advise you
to always use the X-DOS command processor.
Examples If you want to relocate the COMMAND.COM file to the
D:\DOS directory and make it permanent, and also want
to extend the size of the environment to 512 bytes,
you should include the following statement in your
CONFIG.SYS file:
SHELL=D:\DOS\COMMAND.COM /P /E:512
5-17
The TBOPCOD Switch
Purpose This switch will force X-DOS to trap any bad opcodes.
When enabled, if a bad opcode is encountered X-DOS
will terminate the task and exit cleanly without
hanging the machine.
Type Internal Configuration Command
Syntax TBOPCOD = [ON][OFF]
Where ON - enables the TBOPCOD switch
OFF - disables the TBOPCOD switch
Remarks By default TBOPCOD is set to OFF in order to maintain
compatibility with some DOS applications. Note that
this command can only be used with 286 machines and
above.
5-18
The VDISK.SYS Device Driver
Purpose This device driver lets you to set up temporary,
simulated disk drives in conventional memory,
extended memory, or expanded memory.
Type External Device Driver
Syntax DEVICE=[d:][path]VDISK.SYS [mem] [/E] [/A]
Where d:path - is the drive and path to the directory in
which the VDISK.SYS device driver resides.
mem - is the amount of Kilobytes of memory that you
wish to allocate to the VDISK. The default is 64K.
/E - tells VDISK to use Extended Memory (XMS)
/A - tells VDISK to use Expanded Memory
Remarks: Virtual Disks are much faster than hard disks since
the data resides in RAM rather than on the disk.
X-DOS's VDISK can take advantage of XMS Memory or
Expanded Memory to store data.
Note that, unlike MS-DOS's RAMDRIVE.SYS, X-DOS's
VDISK only uses Extended Memory provided by the XMS
driver, thus avoiding conflict with other programs
that take over the extended memory resources.
Examples: Suppose that you wish to have a VDISK of 1 MB of
memory in Extended Memory, you would add the
following statement in your CONFIG.SYS file:
DEVICE=C:\DOS\VDISK.SYS 1024 /E
5-19
The VERSION Configuration Command
Purpose This configuration command sets the DOS version that
X-DOS should emulate. X-DOS emulates a DOS version of
3.3 as default.
Type Internal Configuration Command
Syntax VERSION=x.yy
Where x - is the major version number that X-DOS should
emulate.
yy - is the minor version number that X-DOS should
emulate.
Remarks: Certain application programs and device drivers may
look for, and expect, a certain version number of the
disk operating system in order for them to execute.
If they do not find an expected disk operating system
version number, they will normally terminate
execution and display an error message similar to
"Wrong version number". To prevent any kind of
version number problems, X-DOS provides the VERSION
command.
If for any reason, you decide to change the version
number at boot time do not forget to reset it to 3.3
before loading the command processor of X-DOS. X-DOS
has a data structure format similar to DOS 3.3 but
has capabilities included in DOS 4.x and 5.0. The
choice for 3.3 compatibility was made due to the
reliability of this version and its subsequent
popularity with many users.
Examples: If you want to change the emulated disk operating
system version number in your CONFIG.SYS file to the
version number 3.10, then include the following
statement in the beginning of your CONFIG.SYS file:
VERSION = 3.10
5-20
The VIDEO Configuration Command
Purpose This configuration command greatly increases the
speed of screen updating in text mode.
Type Internal Configuration Command
Syntax VIDEO=ON
Where ON - enables fast screen updating by allowing X-DOS
to bypass the video BIOS when reading and writing to
the screen.
Remarks: If you choose to set VIDEO=ON in your CONFIG.SYS
file, you should notice a remarkable increase in the
speed with which text based programs display
information on the screen. The only penalty this
increase in speed brings is a slight delay in cursor
positioning.
If you are using a very fast VGA display card you
will not need to use the VIDEO=ON option. However,
for CGA, EGA and 8-bit VGA display cards the
difference in speed is very noticeable.
5-21
The XMS Configuration Command
Purpose This configuration command activates X-DOS's internal
XMS driver.
X-DOS's XMS driver is compatible with the HIMEM.SYS
driver available with MS-DOS 5.0. It has the
particularity of being directly integrated in the DOS
kernel.
Syntax XMS=ON
Where ON - is the parameter for activating the X-DOS XMS
driver
Remarks: The XMS driver manages the Extended Memory the way
EMS drivers manage expanded memory. The XMS driver
allows real mode application programs to use extended
memory in a cooperative and hardware independent
manner. It also manages the A20 line that enables the
use of the High Memory Area.
If you relocate the X-DOS kernel in HMA, the XMS
driver will be activated automatically.
5-22
