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- Joined: 16 Dec 2004
- Posts: 495
- Location: El Cerrito, CA
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3D adapter for SMS2 possible?
 Posted: Tue Aug 05, 2003 3:34 pm
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Would it be possible to build an adapter that allows you to play cards on a SMS 2 while also allowing a cart to be plugged in, allowing 3D games to be played?
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- Site Admin
- Joined: 19 Oct 1999
- Posts: 14762
- Location: London
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Posted: Tue Aug 05, 2003 4:42 pm
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Quote > Would it be possible to build an adapter that allows you to play cards on a SMS 2 while also allowing a cart to be plugged in, allowing 3D games to be played?
No. As far as I understand it, 3D games switch the I/O bus between the cart and card ports, which simply do not exist on the SMS. The only possibility would be to hack the games to use the BIOS instead of the card, and that'd cause more problems getting it to boot. Overall, getting an SMS1 would probably be much easier.
Maxim
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- Joined: 28 Sep 1999
- Posts: 1197
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Posted: Wed Aug 06, 2003 12:08 am
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Quote > > Would it be possible to build an adapter that allows you to play cards on a SMS 2 while also allowing a cart to be plugged in, allowing 3D games to be played?
> No. As far as I understand it, 3D games switch the I/O bus between the cart and card ports, which simply do not exist on the SMS. The only possibility would be to hack the games to use the BIOS instead of the card, and that'd cause more problems getting it to boot. Overall, getting an SMS1 would probably be much easier.
I had looked at some 3D games a while back and they don't enable the card port, they just write to $FFFB to control the LCD panels on the glasses.
It could be that the adapter the goes in the card slot detects writes to $FFFB using A0-A14 and /EXM2 (as there's no A15) and ignores the card port enable signal, so it's 'always on'.
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- Site Admin
- Joined: 19 Oct 1999
- Posts: 14762
- Location: London
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Posted: Wed Aug 06, 2003 6:27 am
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Quote > I had looked at some 3D games a while back and they don't enable the card port, they just write to $FFFB to control the LCD panels on the glasses.
> It could be that the adapter the goes in the card slot detects writes to $FFFB using A0-A14 and /EXM2 (as there's no A15) and ignores the card port enable signal, so it's 'always on'.
So it could maybe be linked to the same address lines on the SMS2 BIOS?
Maxim
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- Joined: 14 Aug 2000
- Posts: 746
- Location: Adelaide, Australia
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Posted: Wed Aug 06, 2003 12:42 pm
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The BIOS, Cart slot, card slot and expansion slot all use the very same CPU bus - the address and data lines (exception is that the card port is missing A15). It their respective CE lines that makes separates them, and these are enabled and disabled by IO port $3E. Fact is that if a device ignores the CE line then it has access to the CPU address bus all the time, regardles of which slot it's plugs into. The main problem is that such a device - that plugs into the cart port and has it's own cart and card port - would need the logic to generate the card_slot_CE_signal, i.e. snoop on accesses to IO port $3E. (The SMS2 hardware actually has unconnected CE lines for the card and expansion slots, and the BIOS very well may handle them like the SMS1)
Rounding off here, for the record building a device like the 'powerbase converter' for the sms2 is possible but realistically isn't worth it, like these two have said above me.
a s.
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Limbs a Flyin'
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Posted: Thu Aug 07, 2003 1:24 pm
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or perhaps another less obvious way could be to tap the composite sync signal, remove the horizontal sync and build a mechanism that alternates the lcd panels for each vertical sync signal detected?
Quote > Rounding off here, for the record building a device like the 'powerbase converter' for the sms2 is possible but realistically isn't worth it, like these two have said above me.
fair enough
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