Snes Rom 16 mbits in 27c322

[mgear25]

Hi Doing it one by one is your problem then. The data becomes broken into the wrong locations and is therefore read back to the Console incorrectly.

Since there are two banks of data with a resolution of 8-bits each, the console must see them as one bank with a resolution of 16-bits.
Here is the way it needs to be programmed:

00000000_00000000
11111111_11111111
22222222_22222222
33333333_33333333
44444444_44444444
55555555_55555555

But it is being programmed like this:

00000000_33333333
00000000_33333333
11111111_44444444
11111111_44444444
22222222_55555555
22222222_55555555


Since the Genesis reads the data one line at a time, you can see that it is not getting it correctly.

What you are going to have to do is trick your programmer. Take note of the tWC and tWP settings used for the 27c040 and tell your programmer you are programming a 27c400. Change the tWC and tWP settings top match the 27c040 and then wire the two ROMs into the programmer like my picture above. By doing this, your programmer thinks it is programming blocks of 16 bits, rather than two blocks of 8-bits.

Just be sure to match up the pinout as you will on the cartridge PCB.

Hi Jazzmarazz i have 1 27c322, i want programing a roms snes 16mbits or 8 mbits. How program this eprom? Needed bridges in willem programmer for the roms in pair o dispairs, these is before o after programming?

I know that 27c322 is 16 bits eprom and data bus snes is 8 bits, but if record eprom in pairs how the next example i can program without multiplexer for converting 16 bits bus in two bus 8 bits


00000000_00000000 In pairs conect D0-D7 in dispairs D8-D15
11111111_11111111
22222222_22222222
33333333_33333333
44444444_44444444
55555555_55555555


Pd. Sorry for my bad English

[Jazzmarazz]

Using a 16-bit ROM in the SNES will be difficult.

Without multiplexing, the largest size you can get is HALF the capacity of the 27c322.
You can use the first 8-bits on the data bus as the actual rom data and the second half of the data bus can be left disconnected (hanging).

helpingthing.PNG

The tricky part will be modifying your ROM file to fill the LOWER 8-bits and ignore the HIGHER 8-bits.

00000000_xxxxxxxx
11111111_xxxxxxxx
22222222_xxxxxxxx
33333333_xxxxxxxx
44444444_xxxxxxxx
55555555_xxxxxxxx

The numbers are data and the x's are do not care.

[mgear25]

Ok im very confussing this, thanks for the help im needed investigate more. Ok the trick is the rom thanks i have 1 idea.