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PostPosted: Wed Mar 29, 2017 7:02 am 
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Is there a list of Mappers there are CPLD or other means designs/code for etc So I one wants to make a game such that it can be on a real cart they can see which mappers can be built currently?


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PostPosted: Wed Mar 29, 2017 7:39 am 
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All mappers can be done, including one that doesn't even exist yet, however it might be more or less difficult. Obviously the more complex the mapper, the more difficult it'll be as it'll require either multiple chips or larger programmable chips. So unless you restrict to a particular programmable devices and a particular amount of them per cart, such a list cannot be established. Even if you say "I want to use this programmable chip", in edge cases the only way to know if the mapper fits or not is to try to implement it.

The biggest CPLD which is home-user friendly (can be handled in DIP package, uses 5V signals) and which appears to be still produced today is the Atmel ATV2500.

EDIT : Full MMC1 emulation is definitely possible with this chip (I just finished the design - didn't test on hardware), I don't know whether MMC2/4 or 3 are possible but I doubt it they probably needs way too much registers so they'd have to be split into a PRG half and a CHR half.


Last edited by Bregalad on Wed Mar 29, 2017 11:32 am, edited 1 time in total.

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PostPosted: Wed Mar 29, 2017 11:27 am 
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Location: NE Indiana, USA (NTSC)
If what you want isn't listed in Infinite NES Lives, try asking Paul for support.


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PostPosted: Wed Mar 29, 2017 10:28 pm 
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Ah thanks for the list.

Not using the XC9536/72/144XL chips? they are SMD but not really that painful, and you can get the 72 on a dev board for $15 and they are reprogrammable.

Raster counters would be the main feature I would be interested in. You can get plain banking on a flash chip with TTL chips I would think, slightly cheaper.


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PostPosted: Wed Mar 29, 2017 10:50 pm 
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You might find my page on the wiki about discrete logic mapper golf (or its originating thread on the forum) interesting...


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PostPosted: Thu Mar 30, 2017 10:46 am 
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Quote:
Raster counters would be the main feature I would be interested in.

The most common mapper supporting that would be MMC3. The amount of registers for a full MMC3 would be as following :
  • $8000 Register : 5 registers.
  • $8001 Registers : 7 + 7 + 8 + 8 + 8 + 8 + 6 + 6 = 116 registers
  • $A000 Register : 1 register
  • $A001 Register : 2 registers
  • $C000 Register (IRQ latch) : 8 registers
  • IRQ Counter : 8 registers
Total : 140 registers.

So I guess you'd need 3 ATV2500 chips to replicate a full MMC3 ? That doesn't sound extremely convenient, probably it's better to use a more powerful CPLD (from e.g. Lattice) and use level shifters for it's 20 output pins instead ? You'd need 3 74HC541 or equivalent chips to achieve that.


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