Re: [stella] $F000 or $1000 or what?

Subject: Re: [stella] $F000 or $1000 or what?
From: emooney@xxxxxxxxxxxxxxxx (Erik Mooney)
Date: Thu, 04 Sep 1997 17:20:10 GMT
>It seems to be the standard for Atari 2600 code
>to run from $F000 - $FFFF... I've read that this
>is actually the same as addressing $1000, $3000,
>and so on.  Is there any problem with assembling
>code to, say, $1000?  Will it run on the SC just
>as well as if it was assembled to $F000?
>Because the 6507 is missing some addressing lines,
>does the memory map truly just go from $0000 to
>$1FFF?  I'd find that alot easier to cope with :)
>I'm used to having the full 64K addressable...
>uniquely addressable, I guess.

The upper three bits of the 16-bit address are completely unused by
the 6507 or its bus.  So the 2600's ROM address space runs from $1000
- $1FFF, $3000-$3FFF, $5000-$5FFF, etc, to $F000 - $FFFF.  Seems to be
convention to write for the $F000-$FFFF range.

It can be easier to write bankswitched games for different
addresses... like a 16k game could use $1000 for the first bank, $3000
for the second, etc.

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