Re: [stella] Atari memory

Subject: Re: [stella] Atari memory
From: "B. Watson" <atari@xxxxxxxxxxxxxx>
Date: Tue, 1 Mar 2005 15:12:26 -0500
On Tue, 1 Mar 2005, Paul Slocum wrote:

>> No, but it does have 64K of address space.
> if it were a 6502, but the 6507 can only address 8K (only 13 address
> lines).  So the top 3 MSBs of the address are ignored on the 2600 (which
> effectively creates a mirror every 8K).

I was using the term `64K of address space' to mean there are 64K of
addressable memory locations, from the point of view of the 6507. The
fact that some of the address lines are physically missing doesn't change
the fact that the CPU can address 64K, even if it's addressing the same
stuff at different addresses...

But then if `address space' means that, then what's the term for what
you're talking about? Physical address space? (heh, that would mean I
was talking about virtual address space..  wouldn't that be a neat thing
to have on a 650x!)

Hopefully I didn't confuse the guy who originally asked the question worse
than he already was...

> so if you're ever REALLY short on memory and are using pointers in RAM, you
> can use those top 3 bits for something.  ;o)

Hm, I hadn't thought of that before... neat trick.


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