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Step 2a - Decoding 8 character Game Genie Codes
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Skip this step if you have a 6 character code.
We aren't done yet, because now that we have the binary version
of the code, we have to rearrange the bits so it's no longer
encrypted.
To rearrange the values, we need to have a position system. Each
bit in the bit string represents a different position. When we
arrange the positions in order, we will have the converted code.
Code: 00000110111000000110010011010011
Position: 1678H234-IJKLABCDMNOeEFGafgh5bcd
If we rearrange the code in order of position, starting with
the numbers from 1-8, then the dash, next the letters A-O, and
finally the letters a-h, we will have broken the code. You may
want to break the code up to see the positions better.
Code: 0000 0110 1110 0000 0110 1001 1101 0011
Position: 1678 H234 -IJK LABC DMNO eEFG afgh 5bcd
0110 0000 000 0001
When we go to rearrange this code, we will end up with this
set of bits:
Original: 0000 0110 1110 0000 0110 1001 1101 0011
Rearranged: 0110 0000 1000 0100 0110 0110 1011 0101
Represents: VVVV VVVV -AAA AAAA AAAA AAAA CCCC CCCC
VVVV VVVV: The value of the code. That is, what we change the
addresses value to.
AAA AAAA AAAA AAAA: The address of the code. What we change.
CCCC CCCC: The compare value. We only change the address to
the value if the current value of the address
matches the compare value.
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Step 2b - Decoding 6 character Game Genie Codes
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Skip this step if you have an 8 character code.
To find the correct values, we need to rearrange the bit positions in
the bit string. To rearrange in the correct order, we will need to know
the correct positions to rearrange the bits into.
Code: 110110100101100100011001
Position: 1678H234-IJKLABCDMNO5EFG
If we rearrange the code in order of position, starting with the numbers
1-8, then the dash, then the letters A-M, we will have the correct
values. It helps to break up the code to see it better.
Original: 1101 1010 0101 1001 0001 1001
Rearranged: 1010 1101 0001 0001 1101 1001
Represents: VVVV VVVV -AAA AAAA AAAA AAAA
VVVv VVVV: The value of the code, i.e. what we change the value of the
address to.
AAA AAAA AAAA AAAA: The address of the code. What we change.
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Step 3 - Back to hex
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Codes are much easier to work with in hex, so let's translate
our values back to hex. Just use the same conversion table from
step 2.
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Step 4 - ROM Addresses and ROM hacking
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To get the ROM address, we need to add 8000h to our code address.
Finally, we need to adjust for the iNES ROM header, which is 16
bytes. So we need to add 0010h to our address.
For 8 character game genie codes, there is an extra step. The
compare value. This compare value is used because of the way the
NES works. The NES can only handle 32K at a time. This means that
to use more program data (because 32K is very small), we need to
have different "ROM pages". A ROM page is 32K of data, and there
are usually several of them in an iNES ROM (all .nes files are
iNES roms).
So, to find the correct value, we need to use the compare value.
So, in the hex editor, check the value of the first ROM address
against the compare value. If they match, that's the value to
change. If not, then add 8000h to the value and check that value.
Keep doing this until you find the matching value. Note that
there may be more than one matching value. In that case, you
will need to change them all (that's what the real game genie
does - well, that's glib, but good enough).
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Example of an 8 character code: ATVATGSL
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Step 1) Translate the code and we get: ATVATGSL = 06E064D3
Step 2) So, translate 06E069D3 to binary and we get
0000 0110 1110 0000 0110 0100 1101 0011
Step 2a) Now rearrange the bits to get the correct bit string
0110 0000 1000 0100 0110 0110 1011 0101
V: 0110 0000
A: 000 0100 0110 0110
C: 1011 0101
Step 3) Convert back to hex
V: 60h
A: 0466
C: B5
Step 4) Add the offset values to get the ROM address:
R: 8476h
V: 60h
C: B5
If (R == C) then { R = V, repeat } else { r += 8000h, repeat. }
Anyway, just keep checking values and adding 8000h till all the
C&
#39;s become V's. Simple, no?
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Example of an 6 character code: SXIOPO
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Step 1) Translate the code and we get: SXIOPO = DA5919
Step 2) Convert that the binary and we get
1101 1010 0101 1001 0001 1001
Step 2b) Now rearrange the bits to get the correct bit string:
1010 1101 0001 0001 1101 1001
V: 1010 1101
A: 001 0001 1101 1001
Step 3) Convert back to hex:
V: ADh
A: 11D9h
Step 4) Add the offset values to get the ROM address:
R: 91E9h
Now, just open your hex editor, and change the value of 91E9
to be ADh.
6 digit codes are quite simple, no?
完全没懂
神马东西？
菜鸟默默路过
