Subj : Re: My A2K died :
To   : DENNIS SMITH
From : Neil Williams
Date : Thu Sep 18 2003 10:20:22

Hi,
 On Monday September 15 2003, Dennis Smith said to NEIL WILLIAMS:

 NW>> I think we can say that at least your CPU is working (the blinking
 NW>> power LED).
 DS> I even checked with a meter with 4.5 to 5 volts;same on KSrom. It's
 DS> pin#31 on both chips. So, who signals the CPU to do its jmp start
 DS> vector? KSrom was swapped to a good one-- no change. BTW, this A2K was

The CPU, AFAIK, starts reading from zero on whatever it is connected to, so it effectively control itself.

 DS> Well, I would like to determine a component/device first. Let's look at
 DS> that CTRL+(L)Amiga+(R)Amiga. What's the eletrical equivalent of these
 DS> keystrokes? How is a reset carried out by a device. When I turn on the

The reset is by software, at least on the keyboard controller side. Amigas like the 1200 (and I'm sure 2000, but can't remember!) also control the keyboard reset by software on the CPU side.

Hence, it's the power LED you want to see blink when you reset by C-A-A. If it doesn't blink the problem is in the area of the CPU (when my original CS-PPC died, the LED never blinked and acted the same whether the 4000 had the failed CPU card installed or not at all!).

 DS> A2K, what events & devices actually tell KS to jump to Startup?

When the CPU gets a reset signal, it begins to read from zero at the ROM. That's all that happens, nothing magic. But there's a million & one things which happen next.. god knows what though..

 DS> CIAs around (there are two) didn't change anything. Normal is to read a
 DS> one flash 'caps lock' light at startup and I get that. I'll check this
 DS> one out after shut down.=:D

Yes, but that's handled by the keyboard controller chip - which is independant of the computer (try powering the keyboard seperately from the computer and you'll get the same thing). It does indicate that the keyboard is either sending or receiving a reset signal.

It's the power LED you want to see flash. Even a perpetual guru would be a start :)

 DS> I was there the other night and could not find their repair policy;
 DS> read it a long time ago. They may have dropped the service! Oops, time
 DS> is not looking good for the old Amigas.

If you determine that the fault is on the motherboard, and everything else is fine, get another 2000. They go for very little on eBay. You can even then sell the broken one to get some money back (people will buy any old crap on eBay ;-)


--
 Neil Williams, neil@zeusdev.co.uk - Uni, ug00026 at sees bangor ac uk
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