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Apple IIe Crashes into Monitor
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D Finnigan
Apr 9, 2012, 8:10:20 PM4/9/12
to
For a few months now, my standard (unenhanced) Apple IIe has been having
stability problems, usually manifested by system freezes, crashes into the
monitor, disk motors being engaged (sometimes both at the same time) when
they shouldn't, and garbage characters appearing all over the 80-columns
screen.
I'm running a full system with a RamWorks III with 256 KB, SSC, Transwarp,
Mouse interface, Disk II controller, and Apple 5.25" controller.
I had suspicion that that the Transwarp was causing problems. However, it
seems that if the underlying system is unstable, the Transwarp won't mask
those problems.
The IIe will crash into the Monitor even with *no cards* installed in any of
the slots.
Here is the scenario from last evening:
The IIe had been running on and off for about an hour. I noticed that it was
having problems, so I switched it off and removed every card from every
slot.
I turned it back on, then hit Return a few times. I typed in a 2-line BASIC
program that printed two words on the screen. I typed RUN. The program
executed, and I waited at the BASIC prompt for about 20 seconds.
The IIe then proceeded to crash into the Monitor twice in rapid succession,
with two beeps spaced less than a second apart:
FC26 - A=5E X=0D Y=00 P=37 S=E7
*#
FC26- A=0D X=16 Y=4D P=37 S=DC
*
(hash mark # represents the cursor)
About 30 to 45 seconds later, there was another beep and crash:
3F6B- A=70 X=A0 Y=AF P=FC S=FB
*
It is my understanding that crashes like these are caused by a BRK ($00)
instruction being encountered. However, upon examining memory two locations
back from the reported location, I could find no BRK instructions.
My conclusion then, is that something is wrong with the 64k motherboard
DRAM.
Scenarios just like this, where the Apple IIe crashes into the monitor while
waiting at the BASIC prompt, have happened at least 3-4 times in the past
few months. The Apple runs fine more often than not, however.
I have run the Apple System Diagnostics for IIe (the one that has the
AppleWorks-like interface) several times in the past month, but it does not
report any problems, nor does the built-in IIe self-test report an issue
with the RAM.
Therefore, it seems like the problem is either:
a.) intermittent (fun...)
OR
b.) resulting from some other component
I was measuring the +5 and +12 voltages to see if they were within range.
They were. However, when measuring the +5v across one of the 64kx1 DRAM ICs,
I accidentally made a short across two of the pins. This short caused the
IIe to crash into the Monitor with a beep, as well as several garbage
characters to appear all over the screen.
I wonder if there is a short in one of the DRAMs, or maybe this is just a
coincidence.
As for the other problems mentioned earlier, the disk motors being randomly
engaged and the garbage characters on the 80-cols screen, I have not begun
to investigate the causes yet. One thing at a time, I think.
--
]DF$
Mac GUI Vault - A source for retro Apple II and
Macintosh computing.
http://macgui.com/vault/
stability problems, usually manifested by system freezes, crashes into the
monitor, disk motors being engaged (sometimes both at the same time) when
they shouldn't, and garbage characters appearing all over the 80-columns
screen.
I'm running a full system with a RamWorks III with 256 KB, SSC, Transwarp,
Mouse interface, Disk II controller, and Apple 5.25" controller.
I had suspicion that that the Transwarp was causing problems. However, it
seems that if the underlying system is unstable, the Transwarp won't mask
those problems.
The IIe will crash into the Monitor even with *no cards* installed in any of
the slots.
Here is the scenario from last evening:
The IIe had been running on and off for about an hour. I noticed that it was
having problems, so I switched it off and removed every card from every
slot.
I turned it back on, then hit Return a few times. I typed in a 2-line BASIC
program that printed two words on the screen. I typed RUN. The program
executed, and I waited at the BASIC prompt for about 20 seconds.
The IIe then proceeded to crash into the Monitor twice in rapid succession,
with two beeps spaced less than a second apart:
FC26 - A=5E X=0D Y=00 P=37 S=E7
*#
FC26- A=0D X=16 Y=4D P=37 S=DC
*
(hash mark # represents the cursor)
About 30 to 45 seconds later, there was another beep and crash:
3F6B- A=70 X=A0 Y=AF P=FC S=FB
*
It is my understanding that crashes like these are caused by a BRK ($00)
instruction being encountered. However, upon examining memory two locations
back from the reported location, I could find no BRK instructions.
My conclusion then, is that something is wrong with the 64k motherboard
DRAM.
Scenarios just like this, where the Apple IIe crashes into the monitor while
waiting at the BASIC prompt, have happened at least 3-4 times in the past
few months. The Apple runs fine more often than not, however.
I have run the Apple System Diagnostics for IIe (the one that has the
AppleWorks-like interface) several times in the past month, but it does not
report any problems, nor does the built-in IIe self-test report an issue
with the RAM.
Therefore, it seems like the problem is either:
a.) intermittent (fun...)
OR
b.) resulting from some other component
I was measuring the +5 and +12 voltages to see if they were within range.
They were. However, when measuring the +5v across one of the 64kx1 DRAM ICs,
I accidentally made a short across two of the pins. This short caused the
IIe to crash into the Monitor with a beep, as well as several garbage
characters to appear all over the screen.
I wonder if there is a short in one of the DRAMs, or maybe this is just a
coincidence.
As for the other problems mentioned earlier, the disk motors being randomly
engaged and the garbage characters on the 80-cols screen, I have not begun
to investigate the causes yet. One thing at a time, I think.
--
]DF$
Mac GUI Vault - A source for retro Apple II and
Macintosh computing.
http://macgui.com/vault/
Kevin Dady
Apr 9, 2012, 8:23:19 PM4/9/12
to
stab there is something oscillating on your power, do you have another
power supply to try out?
D Finnigan
Apr 9, 2012, 8:27:49 PM4/9/12
to
Kevin Dady wrote:
>
> too bad you dont have a scope to see whats going on, but as a wild
> stab there is something oscillating on your power, do you have another
> power supply to try out?
I have the power supply in the Apple II Plus, which I believe should work in
>
> too bad you dont have a scope to see whats going on, but as a wild
> stab there is something oscillating on your power, do you have another
> power supply to try out?
the IIe.
As for an oscilloscope, I don't own one at home, but I have access to one.
Michael J. Mahon
Apr 9, 2012, 9:29:32 PM4/9/12
to
You might try running a memory test for a while to see if the problem
is localized to a single bit (chip).
-michael
NadaNet 3.1 for Apple II parallel computing!
Home page: http://home.comcast.net/~mjmahon/
"The wastebasket is our most important design
tool--and it's seriously underused."
Cedric Peltier
Apr 11, 2012, 5:57:12 AM4/11/12
to
points to be checked.
The memory test at http://www.willegal.net/appleii/6502mem.htm helped me
to locate a defective dram on a IIe (the internal memory test said all
memory was bad, but only one dram was bad). The behaviour of this IIe
was somewhat close to what you are describing, except it was unable to
boot from a floppy disk. Behaviour can be widely different depending on
the location of the bad ram.
Without a scope, the memory test and the power supply swap seem to be
the only way to go. But you can also remove and put back gently all
components that are plugged into sockets, contact cleaning could be
appropriate.
If you get a scope to try it, check http://www.willegal.net
Cedric.
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