MAMEWorld Forums - EmuChat - Re: Namco System 22 Video PCB

> 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.

-.-