#Guru Alarm Light Flash
12 messages in this thread
I notice that whenever my machine gurus, due to thermal noise relating to
gravitational acceleration on the moon, the power light sort of flashes,
changes its brightness in a flashing manner. My question is, how is that done?
Is valuable board/chip space used up in connecting this LED to a memory
location?
Alex
Alex,
No…it's not hooked up to a memory location…I once knew the exact
reason for the flashing light…but forget at this point. I believe (and could
easily be wrong) that during the flashing…it's pumping diagnostic information
to the serial port if you happen to have a 9600 baud terminal set up there.
Don
Do you think I could set prefs to 2400 baud, call a bbs, open a message, and
then cause a GURU, having the sysop close the message and leave it for me to
see later?
Alex
Alex:
The output via the serial port on a Guru is generated by the ROMWack at
9600 baud and is independent of the preference setting. That is to say it is
alway at 9600 baud. It probably could be changed by patching the KickStart
code if one knew where to go to look for the USART set up. 73, bill
OK, so it's beyond me. Ok, just asking, it would be interesting to have
somebody's power light start flashing inexplicably, sending the user into
panic.
Alex
Alex — there is a hack that does that… it also puts up random "psuedo-gurus"
that time themselves out and trap the warmstart sequence so you can't kill
yourself with a 3 finger punch… Very funny program, especially if you spring
it on an unsuspecting person (Yes, I did it to everyone here) <grin> –Ben–
Alex:
When I am 'playing around' with code (something that I don't get much
time for anymore), I hook up another computer to the serial port. When the
machine Gurus you can examine what is going on via the other machine and while
continuing to hold the errant task return the OS to an operational status. I
can save a considerable amount of time. It is even 'somewhat safe' to be doing
something else while trying your 'unknown' program. Naturally if you program
munches in the wrong area all will be lost but my experiance is that the OS
usually catches it before it has a chance to do much damage. In any event I
have always been able to 'clean up' before rebooting. I don't know nearly as
much about that debugger as I should and hopefully will but it is quite
interesting. 73, bill
What sort of information is thrown out the serial port?
Alex
Alex:
I am afraid that I don't remember now. I was using that while in North
Carolina over a year ago. Seems like it does nothing until the port receives a
character (DC1, ACK?) then I think it gave a signon message of some kind with
maybe the trap error number and program counter value. The point is that you
can inspect and change memory values as well as restart any of the tasks.
73, bill
You can flash the power light under software control. I will look it up for
you later and post it. The same bit that controls the power light also
controls the audio filter on the A500 & 2000.
GreggT
Alex,
No…among other things…the debug output is at 9600 baud and can't be
changed that I am aware of. It has no bearing on what preferences is set at.
Don
Alex,
It is done using one of the lines on the parallel interface chips. If you want
to call one line "valuable", it's valuable. BUT, it's already found a use: on
the new machines, that line also controls the audio filter.
The LED goes through a special sequence, whose purpose is to alert you as to
status. You'll notice that it starts flashing, slowly. This is Ami saying, "I
have detected an exception, and am about to crash." A person wise in the ways
of the system can set up whatever diagnostic stuff they need at this point. A
second or two later, it starts flashing faster. This is Ami saying, "Okay, I
am NOW CRASHING."
Rick