                              
                              
                    Screen Blanker V1.3
              A Screen Saver Program for OS/2
                              
                                        Alan Ballard
                                        April 14, 1991

Notice:        Screen Blanker is (c) copyright 1991 Alan
               Ballard. It may not be sold, traded, or
               otherwise disposed of for profit without
               permission from the author.

Disclaimer:         This program is offered on an "as-is"
               basis without any guarantee as to correct
               functioning or fitness for any specific
               purpose. The author believes this program to
               work as described, but you use the program
               entirely at your own risk.  It is your
               responsibility to evaluate the suitability of
               the program for your requirements.  In using
               the program, you agree that you will not
               attempt to hold the author responsible for
               any hardware or software damage, loss of
               data, or incidental or consequential damage
               that may result from use of the program,
               whether or not such use is in accordance with
               the instructions.

Purpose:       A screen saver is a program which blanks the
               screen after a specified period of
               inactivity, in order to prevent patterns from
               being "burned-in" to the screen.

Hardware and software required:
               Screen Blanker Version 1.3 requires OS/2
               Version 1.2 or 1.3.  It should work with
               either Standard Edition or Extended Edition
               and with any computer and monitor that are
               supported by OS/2. The current version has
               only been tested with OS/2 1.2 SE syslevel
               XR04073 and 1.3 SE syslevel XR00000.
               
Installation:
               Copy the file SCRNBLNK.EXE to a directory
               that is part of your normal OS/2 search path.
               \OS2 or \OS2\PBIN are good candidates.
               
               Copy the file SCRNBLNK.DLL to any directory
               that is specified in your OS/2 LIBPATH.
               \OS2\DLL is normally used for DLL's, but any
               other directory in the LIBPATH is OK.
               
               Note if you are installing this version to
               replace a previous version of Screen Blanker,
               it is important to also replace the DLL file.
                                                      Page 2

               To do so, it may be necessary to first remove
               Screen Blanker from your startup and reboot.
               
               Then, modify your STARTUP.CMD file to
               activate Screen Blanker each time you reboot
               your system.  The command to do this is:
                    SCRNBLNK /INSTALL
               You may also wish to add an entry for Screen
               Blanker to a Desktop Manager program group so
               you can easily start it at other times.
               
               If you want Screen Blanker to be effective in
               OS/2 DOS sessions, you must also install a
               device driver.  Copy the file SCRNBLNK.SYS to
               a suitable directory (such as OS2\SYSTEM).
               Then modify your CONFIG.SYS file to install
               this driver at startup.  You must add a line
               of the form:
                    DEVICE=C:\OS2\SYSTEM\SCRNBLNK.SYS
               (or wherever you installed the file).  This
               line should go before the DEVICE=... lines
               which install the mouse drivers; otherwise
               Screen Blanker will be unable to detect mouse
               activity within the DOS box.
               
Usage:         Screen Blanker is normally activated from
               your STARTUP.CMD file whenever the system is
               booted, as described under Installation
               above.
               
               Once Screen Blanker has been activated, it
               will monitor keyboard and mouse activity in
               all OS/2 sessions.  If the specified period
               elapses without either being used, the screen
               will be blanked. Optionally, a display of the
               current date and time will be shown in random
               positions on the screen.
               
               The screen can be restored to its previous
               state by pressing any key or moving the
               mouse.
               
               Screen Blanker may also be started at other
               times in any of the usual OS/2 ways -- by
               selecting it from the File System, by an
               entry in a Start Programs menu, or by
               entering the command SCRNBLNK from a command-
               line window.
               
               When Screen Blanker is started it normally
               displays a dialog box that allows you to set
               some options.  The command line parameter
               /INSTALL used at startup suppresses this
               dialog box and uses default or previously set
               values.

                                                      Page 3

               
               If Screen Blanker is already active when it
               is started, the new copy communicates with
               the previous copy to change the options in
               effect. The Remove button in the dialog box
               can be used to terminate a previously-
               activated screen blanker.  The /NOCLOSE
               option may be specified when Screen Blanker
               is started to prevent it being removed.
               
               If the Screen Blanker device driver has been
               installed, Screen Blanker will also blank the
               screen while the DOS Compatibility mode
               session is in control of the screen.
               Alternatively, a separate DOS screen blanker
               may be used in the DOS compatibility session.
               
Command Line Options:
               The following options may be specified on the
               command line when Screen Blanker is run:
               
               /INSTALL  This is normally used when Screen
               Blanker is run from a STARTUP.CMD file.  It
               bypasses the dialog box popup, and installs
               the program with whatever options have been
               previous set up.
               
               /NOCLOSE  This option prevents the Screen
               Blanker from being removed from memory, and
               also prevents changing most of its options.
               If Screen Blanker is run from a STARTUP.CMD
               file with this option, the only way to remove
               it is to remove the command from STARTUP.CMD
               and reboot the system.
               
               /DEBUG    This option causes Screen Blanker
               to maintain some internal debugging
               information.  This option is only of interest
               to the developer.
               
Dialog Box Options:
               The Screen Blanker dialog box allows setting
               various options.

               The "PM Session", "DOS Session",  and "Non-PM
               Sessions" checkboxes allow you to control
               when Screen Blanker is active.  By default it
               is active in all sessions.  If you remove the
               check from "PM Sessions", blanking will not
               be active in the PM session.  Blanking for
               the DOS session will only be possible if the
               Screen Blanker device driver has been
               installed.


                                                      Page 4

               The time interval at which blanking should
               occur may be entered in the indicated place.
               The default is five minutes.

               The "Show clock" check box can be used to
               control whether the time and date are
               displayed during "blanked" periods.  If "Show
               clock" is selected, then the "Colors"
               pushbutton can be used to adjust the colors
               used in the time/date display.  When this
               pushbutton is selected a second dialog box
               pops up containing scroll bars that are used
               to select the colors.

               If the "Save settings" check box is selected,
               then your preferences for the other options
               will be saved in the system OS2.INI file, and
               will be applied automatically whenever the
               Screen Blanker is subsequently started.
               
Caveats:   (1) Screen Blanker uses the OS/2 VioPopUp service
               to blank the screen.  OS/2 limits use of this
               function to one program (session) at a time.
               This means that if a running program has
               taken over the screen by "popping up", Screen
               Blanker will be unable to blank the screen.
               It also means that a running program that
               wants to use the "popup" while the screen is
               blanked will be unable to do so.  Most
               programs that use this function appear to
               wait for the screen to be available, so in
               practice this doesn't seem to be a serious
               problem.

          (2)  Some levels of OS/2 version 1.2 contain a bug
               in VioPopUp which results in a "Protection
               Violation" (Message SYS1943) if the program
               is removed (by selecting the Remove option).
               This occurs only if it has blanked the screen
               one or more times before being removed.  This
               error arises a few seconds after the program
               has terminated and appears to be beyond my
               control.  It is apparently harmless, and has
               been corrected in recent levels of OS/2 1.2.

          (3)  The DOS driver attempts to detect mouse and
               keyboard activity in the DOS box.  However on
               systems, it will be unable to detect mouse
               activity, hence if you use the system without
               any keyboard input, it might blank it even if
               you had been using the mouse.  This will
               happen on systems configured to use "level
               triggered", rather than "edge triggered"
               interrupts (generally AT-class machines). The
               message "Screen Blanker driver can't set

                                                      Page 5

               mouse intercept" will appear during the boot
               sequence.

          (4)  Blanking the DOS session is accomplished by
               switching to PM first; hence it will have a
               side effect of suspending any program that
               was running in the DOS session. If you are
               running a DOS program that will continue
               without keyboard or mouse input for longer
               than your blanking interval, you should
               disable the screen blanker (or touch a key
               occasionally).

Author:        Alan Ballard,
               3452 West 11th Avenue,
               Vancouver, Canada, V6R 2J9

               Compuserve: 70446,44
               Internet:   ballard@ucs.ubc.ca
