Re: [stella] Superchip: What if....

Subject: Re: [stella] Superchip: What if....
From: "Alex Herbert" <herbs64@xxxxxxxxxxx>
Date: Fri, 10 Jun 2005 12:43:19 -0400
> Can anyone tell me what happens if you READ from the WRITE
> bank in a RAM cartridge? For example, if the lower 256 bytes
> are designated as the WRITE block and I READ bytes at those
> addresses, does the data get clobbered?

The superchip can't tell whether the CPU is reading or writing (because 
there's no R/W line on the cart socket) so it will assume that it's a write 
because of the address.  But since the CPU is reading, nothing will be 
driving the data bus, so the RAM will be written to with some *unknown* 
value.  The CPU will also read some unknown value for the same reason.  That 
value may well be $ff, or it could just be noise - haven't tried it.  Either 
way, I would expect it to be reliable.


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