Re: A couple of PET drive problems...

From: André Fachat (
Date: 2007-03-19 19:23:27

> 1. I have a 4040 that when powered up the LEDs blink nine times.  I 
> can't find a flash code table for the 4040 at, but for 
> the 8050 it says it is the Common RAM, $4000 - $43FF.  Could this be 
> the same for the 4040?

I would think so. (also just an educated guess based on the
assumptions that they have similar DOS versions...) 

> 2. With a 2031, it powers up correctly but whenever you try to do any 
> disk access like get a directory or header a disk, the computer hangs 
> until I power off the 2031.  I have already swapped the ROMs and the 
> 6522, but the problem still persists.  I haven't swapped the 
> 75160 and/or 75161 yet.  Could one of these be the problem and if 
> so which one should I swap first?  I am trying to minimize any 
> desoldering/soldering...

IIRC the 75161 is the control lines driver (ATN, NDAC, ...). This
would be the one that would cause a hang. However, I'd rather
measure the input/output signals to check what's wrong before
unsoldering any other ICs.


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