35

Any accelerator for the Amiga work by disabling the CPU and taking over the complete bus system to become the bus master. To accomplish this, a low level signal must be applied by the accelerator to pin BR (Bus Request). The CPU will answer asserting pin BG (Bus Grant). After the accelerator receives this signal, it acknoledges it by asserting BGACK. When ...


16

The first hope is that this is merely the ribbon not sitting well in the socket - try to reseat it; check if a corner didn't fold up. If it's not the case, and you don't have a spare keyboard, you're in for a "surgical" fix. The paths on the ribbon are printed with a kind of carbon component, which is brittle. In particular the fold just above the connector ...


8

TL;DR: It's an illegal instruction error. Most likely you're trying to boot code for a different CPU (like an 68020 or above). Details for (early) errors are defined in the exec/alerts.h file (*1,2). 80 has the high bit set indicating a machine stoping error and 00 indicating CPU errors directly taken from the coresponding exception. 00 would be the ...


5

I wanted to mention additional techniques someone else has tried to strip away the outer foil. The article -- Amiga 600 - keyboard membrane fixes -- doesn't lend itself to blockquotes, so I'll summarize: The author walks through attempts to remove the foil using different chemicals, then discovers by accident that he was able to peel the foil away by ...


5

115-140 ohms doesn't actually sound that crazy, and ignoring the dynamics of semiconductor loads, only equates to around 30-45mA. A normal, working A600 will consume well over 1A. So it doesn't sound like a short to ground to me, and limiting the 5V rail to 1A is likely going to result in a lower power supply voltage as it's simply not enough to power the ...


2

Here are a couple of things you could do to try to localize the issue: See what the current flowing out of the PSU is during and after power-on. That will tell you whether it's sensing a short and shutting itself down. Since you've already determined that there's anomalous resistance between +5V and GND you can probably skip this. Hotspots on the board ...


1

That may be a floppy drive defect, since it errors on all your disks. Read errors in the bootblock may cause the illegal instruction.


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