More silly 3b1 quesitons. :-)

[Bill Mayhew]

One may do screen blanking via the software.  This feature became
available with relase 3.0 of the Unix PC software  (not to be
confused with Sys V, r3!!).  To quote from scrset(1):

scrset(1)

Name:  scrset - set screen save time

Synopsis:  scrset { n }

Description:  Scrset enables and disables the screen save feature.
When enabled, this feature causes the screen to go blank after a
given interval of time has elapsed with no keyboard or mouse input;
the next keystroke or mouse motion restores the screen display.
This is a new feature of the UNIX PC 3.0 release.

The parameter n, if greater than 0, is the number of seconds to
delay before turning off the screen.  N equal to 0 turns off the
screen save feature (this is the default condition).  If n is less
than 0, the screen is immediately turned off.

----

Here are two limitations I've found.  Software writing to a
currently visible window doesn't reset the timeout, thus if one is
passively watching the screen, an occasional mouse movement is
needed.  Limitation two is that the keyboard unblanking requires
pressing one of the typable keys.  Just a shift or alt is not
picked up, thus a careless operator might be apt to enter an
untentional keystroke by lingering on the key too long or whatever.
Limitation two really is nitpicking.

----

As for switching the monitor off; I would have desired being able
to switch it off when the 3b1 is going to be unattended for long
periods of time.  We have had several of our terminals here at work
develop shorted horitonal drive cooupling capacitors in the CRT.
In one case it caused a minor non-serious fire in the monitor.
Since my 3b1 is at home, and nobody is there to keep an eye on it
about 18 hours out of the day, I took the liberty of connecting the
12 volt power input through a toggle switch that I installed on the
bottom of the monitor case.  Naturally, I waited until the warranty
expired before I attacke the computer.  I switch the monitor off
while I am at work.  Since the monitor 12 volt power comes from the
computer power pack, switching the monitor off also cuts down on
the heat inside the computer.  (The monitor draws about 1 amp.)

My next hardware project that is in the planning stages is to
instll an air flow sensor on the fan that will permanantly cut 110
volt input.  Right now, if the fan fails, the power supply will
overhead and trip a thermal sensor; when the power supply cools
down after a few minutes, the computer comes back on.  The repeated
on-off cycle plays hell with fsck and tends to scramble the disk.
It also doesn't prevent the plastic case from warping due to the
heat.

--Bill