Re: Follow-up: 6502 deaths?

[Sabino Maggi <maggi@ien.it>]

> > ... the screen shown by second A2, that
> > now houses the dead 6502, is quite different (many different characters
> > in random positions) from what I previously observed on the original
> > machine, where I had alternate rows "@"s and "!"s.
> > ...
> > The only thing that comes to my mind is related to different
> > initialization of the video RAM.
> 
> The RAM chips on your second board came from a different manufacturer.
> After power-up, the state of the RAM cells is undefined. It depends on
> the chip layout which of them are "1" or "0".
> 
> Swapping the RAM chips you should be able to create different startup
> patterns.

This is more or less what I thought. Then the memory chips are not
initialized at bootup.
What I do not fully understand is whether the content of each memory
location is purely random or is fixed somehow by the control electronics
of the RAM.

Bye 
Sabino