Amiga Hardware
7 messages in this thread
Hello everyone,
I have a question for anyone with hardware knowledge of the Amiga:
the past few weeks I have been experiencing flakey operation of the
keyboard, gameport 0, and the parallel port. The symptoms include the
following:
o Occasionally the keyboard will get stuck in repeat mode. o
Sometimes pressing a key on the keyboard results in a completely
different character being displayed on the screen. o Mouse
works fine in port 0; however, when a joystick is plugged
into the port, the only signal that works is the fire button. o
Files dumped to the parallel port (printer device actually) are not
printed correctly on the printer… The actual output is
consistent
as far as I can tell. For instance, #include is always printed as
#kncnwfg, and NULL is printed as NWNN. (The correct printer is
selected in prefs).
I took the system in to have it repaired, and was told that there
is nothing wrong with it. I am not about to spend $64 to be told that
elswhere… Any replies would be greatly appreciated.
My guess is that CIA-A has gone south on me, but after looking over
the A2000 schematics and reading about the hardware, I am not so sure.
Thanks for listening,
Kraig Kasey – 76300,1511
Oh yeah, I am running 2.04 if that makes a difference.
Kraig,
That printer output shows that bit 1 (value 2) is "stuck" on, thus
only characters that already have that bit set will print correctly, other
characters will "jump" 2 letters in the alphabet.
That is very typical of a blown CIA chip.
Don
No having memorized all the symptoms and functions of the CIA chips, do you
think it would be possible to write a program that could determine if the
CIAs were blown? That would be so helpful to the Amiga community.
Whenever something starts acting funny, I always wonder about those chips.
(Maybe it's the conspiracy theorist in me. 🙂
John,
Yea…as a matter of fact..it probably is possible to write a
program that would test the CIA functions. Of course, like many
things…the CIA chips don't stand alone…thus if the test showed a
problem with the disk drive interface… the problem could lie in the drive
itself rather than the CIA chip.
Don
Don,
Thanks for the reply… I spoke with a few people in the
conference last night after I composed that message and they told me the
same thing. I swapped the CIA chips after hanging up, and it fixed the
problem. The only thing I don't understand is why everything is working
now… I expected the drive select to be inoperable. Any ideas?
Kraig Kasey
Kraig,
Well…my first suspicion would be the problem was not the chip
itself, but that it was loose in the socket. Thus swapping it insured it
was properly seated.
There's other possibilities too.
Don
From you're description, it sounds like bit 1 of your parallel port is
stuck ON