SNES Repro w/ 29f032 chip - FFIV (FFII USA)

Discussion in 'Modding and Hacking - Consoles and Electronics' started by jaskamakkara, May 28, 2016.

  1. jaskamakkara

    jaskamakkara Tinkering in the dark

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    I have been playing around with making SNES repros (using original Jap carts of the same games) using the m29f032 chips on the Type III adapters from buyicnow.com.

    I have successfully made a Chrono Trigger repro, but I got stuck with my FFIV one (that's FFII in the USA originally) - the Mask ROM on the FFIV cart PCB has 32 pins, while the m29f032 adapter board has 38 [edit - 36] pins and, as a result, doesn't fit.

    Should I simply snip the legs off the adapter for the "top 4 pins" (i.e. pins 1, 2, 37 & 38) and solder the rest of them in? Or is it just that the m29f032 chip cannot be used on PCBs with these "shorter" chips?

    I can, of course, use an M27c801 chip instead as the ROM is only 8Mb in size and the 801 has the requisite 32 pins - but that's not the point.

    Cheers
     
    Last edited: May 29, 2016
  2. sanni

    sanni Enthusiastic Member

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    Snip them off and rewire A21 and A20 to GND and WE to VCC.
     
  3. jaskamakkara

    jaskamakkara Tinkering in the dark

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    OK, thanks :) I started to take off the existing Mask ROM and I managed to break one of the caps on the board (because I'm a clumsy fool) - can anyone tell me what the capacitance of it was so I may replace it? I think the other one you can see in the picture has the same colour markings on it:

    (EDIT - I stuck the colour codes into a calculator online, and it says it's a 1.6µF cap - does this sound right? Not sure if I'm making out the colour markings correctly...)

    [​IMG]
     
    Last edited: May 29, 2016
  4. sanni

    sanni Enthusiastic Member

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    Those are just decoupling/bypass capacitors, you can replace them with standard 100nF ceramic caps.
     
  5. jaskamakkara

    jaskamakkara Tinkering in the dark

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    OK, thanks again for your help :)
     
  6. jaskamakkara

    jaskamakkara Tinkering in the dark

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    Just finished it and it works great :)
     
  7. Pikmin

    Pikmin Intrepid Member

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    Can you please confirm that by using these boards you can only go up to 8 mbit in size?
     
  8. sanni

    sanni Enthusiastic Member

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    Every missing address line cuts the size in half, so without A21 it would be 16Mbit and without both A21 and A20 it would be 8Mbit. Or the other way around:
    2^22 = 4194304 bytes. (A0-A21 = 22 address lines)
    2^20 = 1048576 bytes (missing two address lines)

    Maybe you can rewire them manually, I have not testet that.
     
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  9. Pikmin

    Pikmin Intrepid Member

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    Thanks for that. Yeah I've tried rewiring and it works but can get messy
     

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