- Joined: 05 Nov 2014
- Posts: 435
- Location: Auckland - NZ
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Port $3E
 Posted: Tue Dec 12, 2017 9:07 pm
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The page about Port $3E in the development section suggests that on a game gear and genesis bits 5, 6 and 7 have no effect. That makes sense as the extra slots, and probably the extra hardware involved are not present. Does that mean that the cart data is always returned on a game gear or genesis regardless of wether or not thr bits have been set?
And what about a master system 2? I assume the hardware is present so in effect it looks at the card or expansion slots but as they are not actually there so no data is returned?
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- Joined: 28 Sep 1999
- Posts: 1197
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Posted: Wed Dec 13, 2017 3:38 am
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wasup wrote The page about Port $3E in the development section suggests that on a game gear and genesis bits 5, 6 and 7 have no effect. That makes sense as the extra slots, and probably the extra hardware involved are not present. Does that mean that the cart data is always returned on a game gear or genesis regardless of wether or not thr bits have been set?
That's correct. There's actually some logic in a Power Base Converter to prioritize the cartridge when the card is also plugged in so they don't conflict (at least the JP Mega Adaptor, I haven't checked the US PBC). But that's a function of the adapter and isn't related to bits 7,6,5 of port $3E.
Quote And what about a master system 2? I assume the hardware is present so in effect it looks at the card or expansion slots but as they are not actually there so no data is returned?
That's right, there's just nothing hooked up to the other chip select lines so changing their state does nothing.
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- Joined: 05 Nov 2014
- Posts: 435
- Location: Auckland - NZ
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Posted: Thu Dec 14, 2017 10:03 am
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Cool, thank you for that!
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