[stella] ? memory ?

Subject: [stella] ? memory ?
From: Thomas Dunn <td629@xxxxxxxxx>
Date: Thu, 19 Jul 2001 11:46:40 -0700 (PDT)
Hello all,

I am new to 2600 programming, I have been reading
the Stella Programmers Guide and the stuff at Nick
Bensema's page.  I don't really know anything about
hardware, but I've had a little assembly experience.

I have a few questions about memory in stella
programming.  Some of the things I will write
are statements, hoping you'll correct me if I'm wrong.


You write to TIA addresses or registers for graphics,
etc.  Are these really registers, or is it just some
memory space.  Is this really in the TIA, or is it
writing into the 6502's memory?  If its really in the
TIA, why can I say $06 for COLUP0 and not have it just
reference the the 6th byte in the 6502's memory?


The 6502 has 65535 byte-sized locations.  Where is it
safe to store stuff without messing up other stuff?


In the PIA part of the Stella guide, it says "The PIA has
128 bytes of RAM located in the Stella memory map from HEX
address 80 to FF."  So the PIA writes to memory on the 6502
to get its work done, right?  It also says the stack is
normally located from FF on down
The book I got out of the library, _6502 Software Design_
by Leo Scanlon says the stack is in $0100 thru $01FF which
seems to contradict what the Stella guide says.  Is this a
difference in the 6502 vs 6507?

program memory

I get that your program and game data is in the .bin file,
or on the cartridge.  When you turn on the 2600, I suppose
it just starts reading the first byte off the cartridge?
(maybe after doing a little initialization ?)
I've seen stuff about different cartridge sizes, 4K 8K etc
what are the space limitations for the game?

I thank those who've taken the time to read my questions,
  Tom Dunn

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