AutoBlack(tm) -- The screen saver with a light touch -- User Notes Version 1.5
When AutoBlack is installed, after five minutes of user inactivity, the Mac
screen will go black to prevent burning an image of the desktop (or whatever is
on the screen) into the phosphor of the CRT. Any user activity (move the mouse,
press any key, insert a disk) will immediately restore the current contents of
the screen display with no waiting for system "update events" to redraw it. The
five minute timer restarts from the last time of user activity, and may be set
by the user to any desired value. As a special feature, there are two built-in
variants on the delay time. If the mouse is pushed all the way into the top
right-hand corner of the screen, the delay is reduced to about two seconds
regardless of the delay setting, so you can hide the screen in a hurry if you
need to do that. Alternatively, if the mouse is pushed all the way into the
bottom right-hand corner of the screen it takes a couple hours, so if you are
passively watching computer output you don't need to alter the delay time nor
keep moving the mouse every few minutes.
While the screen is turned off an analog clock icon is displayed at random
positions, to show that the Mac is still turned on. The clock will show the
correct time of day if the program running at that time has a normal Macintosh
interface (that is, it is calling the SystemTask trap from time to time). If
the clock shows random times, changing every time it is drawn, it is because
you have not set the time and date correctly since you last removed the battery.
INSTALLATION
AutoBlack can be installed in any of three ways. Primarily it is designed to
install itself in RAM on bootup. To do this requires that it be present in the
system folder on your bootup disk. Alternatively, it can be double-clicked as
an application from any folder. After it is installed, it is not needed on any
disk drive, and it will continue to be active no matter what the Mac is doing,
until you power off, Shut-down or press the Reset button.
The preferred method to install this program at bootup is to copy it to the
system folder of your bootup disk and rename it "MacsBug". The operating system
always loads in a file named "MacsBug" (if it is there) before it does anything else, and it is important that AutoBlack be loaded in first, before any RAMdisk
or even MacsBug itself. If you need MacsBug to be loaded also, rename it
"Disassembler" and it will be loaded in after AutoBlack. Next time you boot up, AutoBlack will install itself in RAM (but the bootup box will say "MacsBug
installed").
AutoBlack is also configured to install as an "INIT" file. In this mode you can
name it anything you wish; System 3.2 and later versions will look for all INIT
files like AutoBlack in the system folder and start them up as part of its boot
procedure. If you have other INITs or the real MacsBug in the system folder,
this may fail. If you have the 128K ROMs (that is, you are using a double-sided
internal drive) the INITs are loaded in alphabetical order; you can just rename
the other INITs so they come later in the alphabet. If AutoBlack is not able to
install properly, a dialog will inform you of its failure. If the AutoBlack
INIT file is named "MacsBug" it is guaranteed to install first, and you will see
both the "MacsBug installed" message and a little notice put up by the INIT.
If other INITs, RAMdisks, or immortal desk accessories have not yet overwritten
the memory required by AutoBlack, you can also run it as an application program.
If you double-click on the AutoBlack icon from the Finder, you will normally get
a message "An application cannot be found for this document." Hold the option
and cloverleaf keys down while double-clicking to avoid this problem. Or you
can use DeskZap, Fedit, or Resedit to change the file type to "APPL". This will
result in a different icon (a Mac screen with the familiar hand in front of it);
you can double-click this icon with no impediment.
You can run the application any time, even after AutoBlack is installed. It
allows you to change the delay time from the default five minutes. Setting the
delay time to zero disables AutoBlack, but you can always run the application
again to start it back up with a new delay time.
My preference is to use AutoBlack in the APPL mode, name it "MacsBug", and leave
it in the system folder. That way it always installs itself at bootup without
requiring manual attention, but I can still easily double-click it to change the
delay setting.
HOW IT WORKS
AutoBlack takes over the alternate display area and paints it black (except for
the clock icon). Then a small task is installed in the vertical retrace queue
of the Macintosh (when it also looks at the mouse and keyboard), which counts
the time since the last user activity. Once the delay time is exceeded, the
video hardware is switched to the alternate display. Any time user activity
takes place, the display is switched back to the normal display area, and the
timer is restarted. The Macintosh software is not told about the switch, so it
continues to update the normal display area; thus the display is immediately
current whenever the hardware is switched back. Programs continue to run
normally even when the display is switched off, and their output will be there
when you switch back. Programs that depend on the alternate screen may not work
correctly, if at all.
Unlike other programs that load in at bootup time, it is essential that
AutoBlack be first to load -- even before the debugger -- to get access to the
alternate screen. INIT files other than AutoBlack often take part of the memory
used by the alternate screen; if they get there first, AutoBlack cannot install
itself. If it fails to load as an INIT, simply rename it "MacsBug" and try
again. Some systems, notably the HyperDrive 2000, rejuggle the memory hardware
at INIT time; there is no way for AutoBlack to install at the proper time in such
a wierd system. Some INITs leave a lot of trash in the heap when they are done;
AutoBlack has been known to crash after such dirty predecessors. Renaming the
files so AutoBlack loads first usually clears up the problem.
NOTICE
AutoBlack¬ is Copyright ⌐ 1987 by Itty Bitty Computers. Version 1.2 was free,
but I put some extra work into making version 1.5 into an INIT and a double-
clickable program, and also making it work with large screen hardware and
software. I'm asking $5 (shareware) if you appreciate AutoBlack and would like
me to write more useful Mac Software. AutoBlack may be freely distributed but not for profit, if it is unmodified and this document is included.
Itty Bitty¿ is a registered trademark of Itty Bitty Computers.
