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Author Topic: About $A10008 and $A1000C for the Sega Genesis  (Read 278 times)

DPMHHacker

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About $A10008 and $A1000C for the Sega Genesis
« on: November 08, 2019, 05:29:01 pm »
Hello, I am a newbie in the ROM Hacking community. I just recently encountered a problem with decoding a Sega Genesis game: This code:

tst.1 $A10008
bne.b
tst.w $A1000C

As you all know, $A10008 is the controller 1 control address, and $A1000C is the expansion port control. However, what I don't get is how it affects the ROM. If contorller one is inserted, does that make $A10008 have a number that is not zero or a number that is zero? Also, how does $A1000C add into all of this? Is it going to be permanently zero, as Sega never announced any expansion port accessories?

In this scenario, does it mean that the code will branch or not?

KingMike

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Re: About $A10008 and $A1000C for the Sega Genesis
« Reply #1 on: November 17, 2019, 08:19:10 pm »
Expansion port? Isn't that what the Sega CD uses to connect to the console?
(it was also used otherwise only by a piece of hardware I think was called the DS-6, an expansion used in demo kiosks to let them plug in six cartridge games (locked inside the demo unit) at a time while letting the player pick a game with a button on the outside of the display.)
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