                Making a RAM Cart for Use on USB CopyNES
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10/08/05
KH
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This is pretty simple if you know what you're doing. 

What you need:

1 NROM cart (SMB, duck hunt, etc.  doesn't matter... just make
             sure it has all the pins on the cart edge!)

1 8K SRAM chip.. i.e. 6164, 6264, etc.  28 pin .6" wide DIP package.

1 32K SRAM chip.. i.e. 61256, 62256, etc.  28 pin, .6" wide DIP package.



1) Remove the two ROM chips from the board, being VERY careful not to
   destroy the plated through holes.  i.e. use a desoldering tool 
   (braid usually doesn't work on this).  Or you can use the cheap method
   which is this:  using a very small pair of wire cutters, carefully cut
   through each pin.  Remove the body of the dead ROM, and then put a 
   small amount of fresh solder on the bottom of each pin sticking out.
   Heat 1 pin with the soldering iron and while holding the board with the
   top half of the pin pointing down, sharply hit the table with your hand
   (holding the board) JUST after heating the solder... The idea being
   the solder will still be molten when you hit the table with your hand
   (holding the board). This should cause the pin and most of the solder
   to shoot out and hit the table.  Repeat for all 56 pins.  Now that
   all the pins are gone, you can use a solder sucker or solder braid
   to now clean the holes.  Sometimes a straight pin or needle can work-
   heat the hole (carefully!) with the iron and poke through it fast. 
   Whatever you do, DO NOT DAMAGE THE HOLES.  If a metal "circle" comes
   out from the hole, you pulled the through hole out and caused a big
   problem.  So don't do that.

2) bend pin 27 up on the 8K RAM chip.  Bend pins 1, 20, 22, and 27 up
   on the 32K RAM chip. 

3) Solder the 8K RAM chip next to the lockout chip, and the 32K RAM chip
   in the remaining location.  Be sure to observe pin 1 orientation!!
   The board has a little outline on it to show which way the notch
   goes.  If you screw it up, you'll be in a world of hurt.  So, don't
   screw it up :-)

4) You will now have to solder a small piece of wire on the bottom of the
   board across pins 26 and 27 of the 8K RAM chip.  This will connect +CE
   to VCC.

5) Now the fun begins.  Get some small solid copper wire with insulation...
   i.e. phone wire (around 24-26 gauge).  You will need to solder 4 wires
   on to complete the job.

6) Solder a wire from pin 27 of the 8K RAM chip to pin 56 of the cart
   connector.  Looking at the bottom of the board with the connector 
   pointing down, this pin is to the left of the two connected together.
   Scrape off the green crap at the end and solder the wire there.  I
   looped the wire around the board from the top to the bottom on the edge
   opposite of the connector.  Be sure the wire comes off straight from
   the solder point on the cart connector.  This will be important later.

7) Solder a wire from pin 27 of the 32K RAM chip to pin 14 of the cart
   connector.  Scrape the green gunk off the end of the connection and
   solder it there. Be sure the wire comes off straight from the solder 
   point on the cart connector, as far back as possible.  This will be
   important later.

8) Solder a wire from pin 22 of the 32K RAM chip to the bottom of pin 14
   of the same chip.  This will ground /OE.  I soldered the wire to the 
   pin "backwards" and ran the wire over the back edge of the board.

9) Solder a wire from pin 20 of the 32K RAM chip to pin 22 of the board
   under said 32K RAM chip.  This will connect /OE on the board to /CE
   on the RAM.

10) Almost done.  Now, this is why making those wires come out straight
    was important.  Put the board back in the cart case and notice that
    the two pins soldered to the cart edge hit the case.  Get a marker
    and put a dot above the case halves where it hits.  Take it apart and
    cut those places with the wire cutters into a "V" shape so that when
    the cart is put back together, the wires clear through the middle of the
    V you cut.

11) (optional)  You can do 1 of 2 things.  Either make 2 of these carts, or
    put a toggle switch on your cart to select mirroring mode.  Personally,
    my mirroring is fixed to "H" type which seems to be good enough for
    alot of things.  If you wish to put a switch on yours though, find a
    small SPDT toggle switch (radio shack, off of a dead modem, etc) and
    find a place on the end of the cart where you can put it so that it
    won't hit when you install the cart into the NES.  Wire it up so that
    the middle connection of the switch connects to the common on the H and V
    pads (near pin 28 of the 8K RAM chip) and the other 2 pins connect to
    the other pads on H and V.  Toggling the switch will then change
    mirroring on the fly.  It is safe to flip the switch while the NES is
    running.

   
