COMSS.ASM : 2-April-1995: A COMx screen saver based on RI and DCD!
Copyright (C)1995 Cornel Huth

Since my fax prg still has no real screen saver after all this time (I won't
mention it) I've blown an evening writing this (from scratch, mind you). The
difference between standard screen savers and this is that this one uses the
comport to detect when to blank and when to unblank.  Upon a Ring-Indicator
(RI) COMSS unblanks and remains so so long as Data-Carrier Detect (DCD) is
valid.  As coded, it expects a VGA, but you can change this if you have an
assembler and a little asm know-how.  The blanking of the screen is enough
for most monitors to move into a standby mode (e.g. NEC 4FGe).  If you need
specific support for your monitor (see the BLANK routines below), code it
as is required.

The program is operated like this:

Install:

 C>COMSS n     where n is your modem com port, 1 through 4
               for example, C>COMSS 2  if the fax-modem is on COM2

After a good install, you still need to activate it:

 C>COMSS +     to activate the screen saver, or:
 C>COMSS -     to deactivate the screen saver

When active, you can still unblank the screen at any time by turning on
the ScrollLock.  It remains visible so long as ScrollLock is On.  It will,
of course, all become visible as soon as someone calls and remain so while
they are connected (and for 20 seconds after they hangup).  Memory use is
about 300 bytes when resident.  It makes use of INT1C vector, and chains to
the previous handler.  It remains in memory until your reboot.  It's really
pretty simple stuff, and it could be done much more easily in the fax program
(probably 5 lines of Pascal), but the thing is, it does what I want it to.

For updates to this program, or for other programs and, especially, programmer
toolkits for database, soundcard, multimedia, graphics, etc., for
DOS, Windows, and OS/2 compilers (BASIC, C, C++, etc.), check out my sites
listed below:

(FTP) ftp.crl.com /users/ro/cornel --- (WWW) ftp://ftp.crl.com/users/ro/cornel
BBS/fax: +1-210-684-8065 / Monday-Friday after 5pm / Weekends 24 hours [-0500]
            - Bullet/DOS - Bullet/Win - Bullet/2 - Ruckus/DOS -

e-mail: cornel@crl.com