By Dave Fallen / 524 Ranger Dr. S.E. / Olympia, WA 98503
Placed in the public domain -- February 14, 1988
Updated May 25, 1989

Version 2.0

This program blanks the code responsible for noise in
many programs. The program code OUT 61,AL (hex E6 61)
is changed to NOP NOP (hex 90 90). The program attempts
to avoid changing DATA, or the use of port 61H to issue
a keyboard clear signal. Once the sound code is blanked,
your program will run silently. This program will NOT
modify your original program, but will create a clone
with the 'noise code' blanked. Output will use the drive
and file name of your choice or, if you prefer, to a
computer-generated default file name on the default drive.


SYNTAX: SILENCER [d:] filename [[d:]filename]

This program is not infallible, but it will quieten most
programs. There are several ways to code sound in a
program, but SILENCER checks for the most logical and
common methods of accessing the programmable interface chip.

The default filename for the new file is either (1) the
letter Q is added to the file name, or (2) if the
original filename is 8 letters long, the 8th letter is
changed to a Q. If a file already exists by this name,
SILENCER will permit you to quit without overwriting
that file. You may specify a different filename for
output when SILENCER is invoked. Make sure there is
sufficient space on the specified drive to write the new
file. The new file will be exactly the length of the
old file. If you do a COMP/B OLDFILE.EXE OLDFILEQ.EXE,
for example, you will see that the two files are
identical except for some occurrences of E6 61 replaced by
90 90.

Note for compiled BASIC users: If the program you wish
to silence is a compiled BASIC program which requires
the runtime module (BRUN20.EXE, BRUN30.EXE, BRUN40.EXE)
then it is the runtime module itself which needs to be
silenced, not the compiled BASIC program! However, your
BASIC program is not going to recognize BRUN40Q.EXE so
you will have to rename it to BRUN40.EXE before the
program will run. Because you can't have two files with
the same name, the original BRUN40.EXE will have to be
kept on a separate disk or directory.


SILENCER will have NO effect on source code, e.g.,
program with the extension of .BAS . If you want to
silence BASIC programs run under an interpreter (e.g.,
BASICA or GWBASIC) the offending statements themselves
need to be removed (or better yet, turned into a
non-executed comment). These are statements such as
SOUND, and PLAY. If compiled, however, SILENCER will
effectively quieten these statement in the .EXE file.

MAY 25, 1989 UPDATE:

(1) added logic to avoid blanking a hex E6 61 sequence
if it occured in data (not code).

(2) added logic to detect when port 61H was being used
to clear the keyboard. Avoids blanking the hex E6 61
sequence in this case (otherwise, a keyboard lockup
will occur when the modified program is run).

(3) if no noisemakers are found in the source program,
the "modified" program (actually a duplicate of the
original) is erased -- as always, the original program
is untouched.


* * * * * * *
* NOTICE *
* * * * * * *

Although I have placed this program in the public domain, I
intend to continue supporting it. If you find any program
that SILENCER has trouble with, let me know. Of course, if
it is a commercial program I don't have, I may not run out
and buy it (after all, SILENCER is not generating any income!)
But if you can legally send me a copy of the troublesome
program, I'll be glad to work on it and get back to you.
----------------end-of-author's-documentation---------------

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