ProfitPress Mega CDROM2 …eeware (MSDOS)(1992)(Eng)/ProfitPress-MegaCDROM2.B6I/UTILITY/SCREEN/BLANKOP.ZIP/BLANKOP.DOC

Text File | 1990-09-22 | 10.4 KB | 232 lines

       BLANKOP - a hardware-independent screen saver for IBM
       PC compatibles, proprietary to Olaf Pors.
       Copyright (C) 1990 by Olaf Pors.  All Rights Reserved.

   It is a fact that screen phosphors can be burned out if stationary
patterns remain on the screen for long periods.  Your monitor has
probably been damaged in this way if dark areas appear on a normally
green, blue, gray or amber screen after the monitor has been turned off.

   A screen saver can preserve the life of your computer monitor by
"shutting off" the screen when inactivity at the keyboard indicates that
the computer is not in use.  After it has been started up, a screen
saver program sits quietly in memory until the keyboard has been idle
for a while, then blanks the screen.  Hitting a key restores the screen.

   As important as screen savers are, they can be disappointing.  One
screen saver works on a monochrome system, but not on a color system.
Another that works on one color system may not work properly on yet
another color system.  You may, as I did, purchase a computer bundled
with a screen saver that hangs the machine when certain VGA programs are
run, and makes a mess out of the screen when GWBASIC is active.  You
may, as I did, contact the vendor who knows about the problems, but can
do nothing about them.

   The basic difficulty with all of these screen savers appears to be
that they directly access video hardware.  The rules for such accesses
change with the hardware.  The result is that in many cases a different
screen saver is needed for each computer.

   BLANKOP only uses standard well-documented interfaces to the video
hardware and therefore works on different hardware.  The only
requirements are that the computer be 100% compatible with the IBM
PC/XT/AT or PS/2 families, and that the operating system be PCDOS or
MSDOS version 3.0 or higher.

   To get started, be sure you are willing to abide by the Terms and
Conditions listed further below, and that you have read the Disclaimer,
also below.  Then just execute the program by typing

      BLANKOP

   Optional parameters are described below, but the default values
should be appropriate in most cases.

                             DISCLAIMER

   Olaf Pors disclaims all warranties relating to BLANKOP, and will not
be liable for any damages of any type resulting from the use of BLANKOP.
BLANKOP is used entirely at your own risk.  The list of limitations
(given below) on the performance of this software is not guaranteed to
be exhaustive.

                         TERMS AND CONDITIONS

   BLANKOP is supplied in two versions.  The "free" version, identified
by an "F" following the version number, requires you to depress a key to
acknowledge that you have seen the startup messages.  It also always
blanks the screen after one minute of keyboard inactivity.  The
"commercial" version, identified by the absence of a letter following
the version number, does not require an acknowledgement and allows you
to select the idle time before blanking the screen.

   The free version of BLANKOP may be executed, copied and distributed
without charge, but only in its original unmodified form.  Every copy
must be distributed along with the original unmodified BLANKOP.DOC
documentation file.

   After using and examining the free version, you may wish to purchase
the commercial version of BLANKOP.  Purchasing instructions may be found
at the end of this document.  The commercial version may be used on only
one computer at a time.  For example, if you have two computers, buy two
BLANKOP licenses.  You may then make sufficient copies for those two
computers only.  Otherwise, copies may be made only for backup purposes.
You may not distribute copies of BLANKOP for more than the number of
computers you purchased licenses for.

                 BLANKOP MODES AND LIMITATIONS

   BLANKOP operates in one of two user-selectable modes: VGA or non-VGA.
If your system has a BIOS which supports the IBM VGA standard, the VGA
mode is recommended, but not absolutely necessary.  Non-VGA is the
default.

Non-VGA mode:

  In this mode, BLANKOP occupies 5.4 kilobytes of memory.  The contents
of the active display page of video memory is manipulated when the
screen is blanked.  This is noticeable when a program continues to
output to the screen after the screen is blanked; such program output is
periodically "swept off" the screen into a storage area and is restored
when a key is hit.  The following limitations apply.

1. Some programs may switch the active display page to another page.  If
   so, BLANKOP continues operations on the previously-active page, with the
   result that the screen does not blank as long as the new page remains
   active.

2. The screen is blanked only if the display is in text mode (video modes
   0-3 or 7).  Most programs operate in text mode, even when displaying
   menus and colors.  If a program uses a graphics mode, the screen is not
   blanked until the display returns to text mode.

3. A specific video character attribute value is used as a unique
   "signature" by BLANKOP.  By default the value is 0.  In unusual cases
   another program may also put characters into video memory with a 0
   attribute, which results in BLANKOP getting confused and distorting the
   appearance of the screen (harmless, but annoying).  If this should
   occur, a different attribute value may be selected using the "-attrib"
   option.

4. A few programs manage screen memory directly, without going through the
   standard DOS or BIOS interfaces.  If such a program scrolls the display
   (moves the entire contents of the screen up or down) while BLANKOP has
   blanked it, the display may not be restored accurately when a key is
   depressed.  This is unavoidable, but also is probably of little
   consequence since scrolling probably will continue after the screen is
   restored, so that the screen is "cleaned up" after at most 25 lines have
   been scrolled.

5. It is conceivable that a program may read back the characters it has
   previously written to video memory.  This is extremely bad programming
   practice, since it is usually not possible to predict when a message
   from DOS or another memory-resident program might appear, thus
   overwriting areas of video memory.  However, such a program may fail in
   unpredictable ways if BLANKOP blanks the screen.  This is viewed as a
   deficiency of the program, not BLANKOP.

VGA mode:

  In this mode, BLANKOP occupies 1.3 kilobytes of memory.  None of the
limitations listed above apply.  This is the recommended mode of
operation if your computer supports the IBM VGA standard.

  If you aren't sure whether or not you can use this mode, you may try
it, but be somewhat cautious.  A properly written BIOS should always
handle VGA calls harmlessly, but if you want to be safe, boot your
computer from a spare floppy disk when trying this.  If the screen
doesn't blank when it should, use non-VGA mode.

                BLANKOP COMMAND LINE OPTIONS

-time nnn units

   Specifies the idle timeout, up to approximately 1 hour.  "nnn" is the
   number of seconds or minutes.  "units" is a string beginning with "m" to
   indicate minutes, or beginning with "s" to indicate seconds.  For
   example, "-time 5 min" indicates a 5-minute timeout.  The default is 3
   minutes in the commercial version.  This option is not available with
   the free version.

-attrib nnn

   Specifies the special attribute byte value used during non-VGA
   operation.  If you find that the screen becomes distorted after being
   blanked or unblanked when a certain program is executed, try
   "-attrib 128".  If this doesn't work, try 8 or 136.

-help

   A summary of options is displayed.

-vga

   Tells BLANKOP to run in VGA mode.

-others

   A limitation faced by any memory-resident program activated by
   keystrokes is that other programs which intercept keystrokes may be in
   memory at the same time.  If so, whichever program was executed last
   gets "first pick" of the keystrokes; the program may or may not forward
   keystrokes to the others.  Therefore, the following could happen.
   BLANKOP is executed and remains in memory.  Program X is executed and
   continues executing for quite some time.  The screen is blanked after
   timeout.  Now, if X intercepts keystrokes and does not pass them on to
   BLANKOP, BLANKOP is never able to unblank the screen.  If you execute a
   certain program, the screen blanks and cannot be unblanked again, use
   "-others".  This option prevents BLANKOP from blanking the screen after
   an idle timeout if BLANKOP is not getting "first pick" of the
   keystrokes.

   It is possible to verify correct installation of BLANKOP from within
a batch (.BAT) file with a sequence of commands such as:

        blankop
        if errorlevel 1 goto l
        echo no error
        goto end
        :l
        echo error
        :end


   BLANKOP has been tested on the following systems:

Hardware                Operating System

IBM PC-XT               PC DOS 3.3
Northgate 286 w/ VGA    MSDOS 4.0.1
AT&T 6300        MSDOS 3.2
Win TurboAT        MSDOS 3.3
Xerox 6060        MSDOS 3.1
IBM PS/2, model 50      PCDOS 3.3

                PURCHASING INSTRUCTIONS

   The following offer is valid only until September 1, 1991.  To
purchase, send eight dollars for each program license required.  For
example, send 40 dollars to be able to use BLANKOP on 5 computers.  Also
send a self-addressed diskette mailer bearing sufficient return postage,
and one empty FORMATTED diskette to:

        Olaf Pors
        723-C Mountainwood Road
        Charlottesville, Virginia 22901

The money must be in the form of a check or money order.  Purchase
orders or credit card purchases will not be accepted.  The diskette must
be 5.25-inch, 360 Kb or 1.2 Mb.  The mailer must bear a prominent
"FRAGILE" warning to prevent diskette damage.

   For USA customers only, if you would like us to supply the diskette,
mailer, and postage, send eight dollars for each license required, plus
seven dollars (e.g.  15 dollars for one license, 47 dollars for 5).  One
5.25-inch 360 Kb diskette will be mailed to the address you specify.
The address must be within the USA.

   Normally, you should receive the commercial version of BLANKOP in
less than 3 weeks.