> Very likely, Namco started out with a CPLD and as production volumes increased, they > had a semi-custom (likely standard-cell) gate array manufactured. There might be some > differences which may reflect in design changes between PCB revs. > Additionally it is likely that Namco was pushing the CPLD too hard (a lot of logic, > high frequencies), which causes it to overheat and eventually fail.
This can explain the bus error in greater detail.
> These are gate arrays that contain gate and register logic, not MCUs. A > 1250-macrocell CPLD is too small to contain a soft CPU core. They likely do some sort > of video processing, based on their function.
Excellent. That leaves a little less of a concern on that end.
> A new/blank/reclaimed EPM7064 would have to be programmed before use. > Meanwhile, a replacement C407 would already have the logic either produced at the > factory, most likely being a standard cell gate array. > If you can find an EPM7064LC44-7 or -10.
> In order to dump one of these, one should first attempt to do so over JTAG (if the > port can be identified on the board) or by desoldering and attempting to dump with a > programmer that supports it. However, it is very likely that the security bit is set, > which would require decap to attempt to remove protection.
> EDIT: Looking more closely, if this is an EPM7064 and not an EPM7064S, there is no > JTAG and it has to be programmed out of circuit. > > The EPM7064S is a much better chip, but the format of the bitstream (the "code" that > defines the register and gate logic on it) is almost certainly different and > therefore incompatible... and reverse-engineering PLD bitstreams is not particularly > fun.
Meanwhile, I can confirm that chip is indeed am EPM70064 without the S so I am kind of stuck until the working pcbs arrive. I would like to confirm the game behavior if a EPM7064 or C407 is removed from a System Super 22 video pcb. These games run fine in Mame however so there could be something in the driver source that can help with programming that EPM7064.
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