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>From: Mark De Smet <desmet@xxxxxxxxxxxx>
>To: stella@xxxxxxxxxxx
>Subject: [stella] byte 000h; atari models
>Date: Sun, Dec 27, 1998, 4:50 PM
>
>
>If you recall, I have been working on a RAM based cart that can be
>programmed via a file copy(In the future I'll write a nice UI) to a
>parallel port. I've got it mostly working, but have 2 questions that
>hopefully someone knows something about.
>
>What is stored at 000h(in the ROM)? I mean is it something specific like
>a startup vector or anything? What would happen if it was changed?
>Specifically what would happen if it was changed to be identical to byte
>FFFh? I have not done any programming(in 6502 anyway) yet, so I am not
>familiar with the exact locations of data in the ROM address space for
>the 2600. I belive my cart circuit is doing 4097 writes which is causing
>the counter to wrap around and rewrite the first bit.
Nothing special is at location 000H in Atari 2600 ROM. Only the bytes at
offset 0ffcH and 0ffdH matter. Everything else can be anything you want.
Burger
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