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1989-04-09
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H E R C S A V E 1 . 3
Hercules Graphics Card (tm) Screen Blanker
Version 1.3
(C) Copyright 1988,89 - Benjamin Diss
Limited permission is granted to individual users for product
evaluation and testing. Continued use of this shareware program
requires registration as described later in this document.
All other rights are explicitly reserved by the author.
- INTRODUCTION -
Images that appear on a computer monitor for an extended period of
time may burn the phosphors of the monitor. This leaves a ghost image
on the screen. To help eliminate this problem a hoard of screen
blanking utilities have been distributed. These programs install
themselves in memory and monitor keyboard activity and sometimes even
video activity. When there is no activity they blank the screen,
assuming that the user has no immediate need for it.
Unfortunately, none of these programs work properly with the Hercules
Graphics Card (HGC) while in graphics mode. When these programs
restore the screen they assume the video card is IBM compatible and
treat it as such. This results in a screen full of "garbage"
characters.
HERCSAVE eliminates this problem by working within the limitations of
the HGC. It allows screen blanking in both text and graphics modes.
(1)
- USAGE AND INSTALLATION -
HERCSAVE operates by turning the display off after a user specified
period of keyboard inactivity and on when a key is pressed. HERCSAVE
does not monitor video activity as some other blankers do.
HERCSAVE can be installed by typing the following at the command
prompt:
HERCSAVE s [/o]
s - represents the number of seconds of keyboard inactivity before
blanking. It is a mandatory entry.
/o - causes the program to use the optional retrace blanking routine.
The time before blank may be changed after the program is installed by
entering the command again with the new seconds. The blanking method
cannot be changed once HERCSAVE is installed.
HERCSAVE supports HOT-KEY blanking. Once installed, pressing
<ALT>-<LEFT SHIFT> will instantly blank the screen.
There should be no need to use the optional blanking method. Install
the program in your system and use it. If you notice anything unusual
after the screen restores in graphics mode you may want to try the
optional method.
The program is intended to be run from the autoexec.bat file.
HERCSAVE is a well behaved resident program so it can be loaded in any
order with other resident programs. Use your favorite text editor to
place the appropriate entry into your autoexec.bat file.
(2)
- TECHNICAL CONSIDERATIONS -
The screen can be blanked and restored using two methods. The default
is to set the vertical size to zero to blank and restore the size to
restore the screen. The optional method turns the vertical retrace
off to blank and on to restore the screen.
The program installs only the required code. Any routine not needed
is not in resident memory after installation.
The program copies the required blanking and restoring procedures to
the resident code space. It redirects only two interrupts and uses
minimal memory by releasing the environment space before going
resident. Version 1.3 requires only 496 bytes of resident memory.
History:
4-2-89 Version 1.3 introduces SafeWare! HERCSAVE now checks its
file image against a pre-caclulated 32 bit CRC. This warns
of viril infection.
Elaborates on the light pen register tests and no longer
aborts after failing.
3-4-89 Version 1.2 fixed a bug in the hot key routine (thanks to
John Lin) that caused some toggle keys (Ctrl, Shift, etc.)
to appear "stuck" after restoring.
Added test to check for proper light pen register responses.
Program aborts if this test fails.
12-8-88 1.1a changed the default blanking method to 'verticle size'.
(3)
- REGISTRATION AND DISTRIBUTION -
The general public is encouraged to share and distribute copies of
this program free of charge provided the distribution file is kept
intact and all files are unaltered. Users who find HERCSAVE useful
and intend to use it must register their copy. Registration entitles
the user to a current version of the program, technical support, and
product upgrades.
Support from users allows the author to develop additional features
and future versions of the program. Any comments, either good or bad,
are welcome as user feedback stimulates the design process. Your
payment of $15.00 would be greatly appreciated. Send payments and
other correspondence to:
Benjamin Diss
The Smart Solutions Group
5800 Oakwood Dr.
Suite 1B
Lisle, IL 60532
The author may also be reached on CompuServe and GEnie:
CIS# 71270,341
GEnie - BDISS
The assembly language source code, site licenses, and custom versions
are available from the author for a modest fee.
Hercules, Hercules Graphics Card, and HGC are registered trademarks of
Hercules Inc.
IBM is a registered trademark of International Business Machines Inc.
(4)