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Writing to w27c512


Aaron Spinks

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You can not use this PCB for games larger than 32k, they require a different mapper chip.

 

You could use a 27C512 EPROM but you can still only use 32k of it. From looking at the pinouts, it should just work. To be safe, double the ROM by burning the 32k image to both the first 32k and last 32k of the ROM, then it won't matter what the PCB holds pin 1 at.

 

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First of all, if you program the chip, make sure you use the correct chip type.  If it applies programming voltage to pin 1 of your W27C512, it will probably fry it.  Also, it won't apply programming voltage to pin 22 like it's supposed to.

 

With that out of the way, did you try reading the programming back to make sure you got what you wanted?

 

Normal operation for a W27C256 has pin 1 at +5V, so your addresses will always be in the 0x8000 range on a W27C512.  So yeah, write a bunch of zeroes to the first 32K if anything, and then write the game to the high 32K.

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