Jan 192018
Echo comments to the screen during CONFIG.SYS loading.
File COMMENT.ZIP from The Programmer’s Corner in
Category Utilities for DOS and Windows Machines
Echo comments to the screen during CONFIG.SYS loading.
File Name File Size Zip Size Zip Type
COMMENT.DOC 2816 1292 deflated
COMMENT.SYS 384 306 deflated

Download File COMMENT.ZIP Here

Contents of the COMMENT.DOC file


COMMENT.SYS is an MSDOS 2.0(+) device driver whose function is simply to
echo a string to the standard output device. The driver code is not actually
installed by dos, so no memory is wasted, and the driver can be referenced
in CONFIG.SYS as often as desired.

COMMENT.SYS is invoked by including a line like the following in your

DEVICE=COMMENT.SYS T\his is a \COMMENT.SYS \comment using '\\' escapes.

Since DOS converts all characters on the CONFIG.SYS line to upper-case,
it's necessary to use a special 'escape' character to preserve lower-case
input, and the backslash ('\') character was chosen for this purpose.
When COMMENT.SYS sees a single backslash character, it starts converting
characters to lower-case; the conversion continues until another single
backslash character is encountered. To make an actual '\' character appear
in the output without toggling the lower-case conversion, just use two
backslash characters together ('\\').

As an illustration, the CONFIG.SYS line above would be echoed as follows:

This is a COMMENT.SYS comment using '\' escapes.

The maximum length of the input string is 255 characters. The count starts
immediately after the 'DEVICE=' string, and includes '\' escape characters,
so the actual maximum length of the echoed string will be somewhat shorter.


COMMENT.SYS can be used to send ANSI graphics commands to the console
(assuming, of course, that ANSI.SYS has been installed by a previous
CONFIG.SYS line). The following line, for instance (adapted from an example
in the DOS 3.0 Technical Reference Manual), would reassign the F10 key to a
DIR command followed by a carriage return:


The '' refers to an ASCII 'ESC' character (27 decimal, 1B hex), which
can be entered using many text editors. The '\' preceding the 'p' is
necessary since the 'p' must remain in lower-case for the command to

I'll leave other potential uses for COMMENT.SYS to your imagination.


COMMENT.SYS has been tested under PC-DOS 2.0, 2.1, and 3.0. It seems free
of bugs or side-effects, but while I would like to be informed of any problems
you may encounter, I can't be responsible for any possible damage and/or
loss of data that may result from the use of COMMENT.SYS.

The program was written at the suggestion of Walter Kennamer (CompuServe

Skip Gilbrech
90 Lexington Ave. #10-G
New York, NY 10016
CompuServe 71445,534
(please leave messages on PCS-131)

 January 19, 2018  Add comments

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