Anyone actually use a XC9500XL series with the NES?

Anyone actually use a XC9500XL series with the NES?
by 2600 on 2010-06-24 (#63327)

There has been a little bit of talk, but I've wondered if anyone has actually used a XC9500XL series before with the NES. Any issues noticed?

I've been planning to stick to the XC9500 series, but the XL is often tempting.

by Memblers on 2010-06-28 (#63433)

I haven't used either, but AFAICT any device that is 5V-tolerant should be just fine without any kind of external protection. Actually, later I'm planning on trying a device that isn't 5V tolerant, but will use series resistors to make it so (as described in one of Xilinx's app notes), so wish me luck on that, heheh.

Timing-wise you need to be careful with the PRG bus (because of odd sprite-DMA issues and maybe other stuff), but the same thing applies when using 74-series chips or anything else as well.

by 2600 on 2010-06-29 (#63479)

The 5v tolerant part doesn't bother me as much as the lack of pull-ups on the data bus. If pull-ups were allowed, this wouldn't even be an issue.

Could you describe a bit more in detail your last sentence?

by Memblers on 2010-06-29 (#63490)

I don't know what's going on for sure, but what I've encountered while using an EPROM emulator was that sometimes just one or 2 sprites (I think always the same ones, too) would be corrupted. What I believe is that the sprite DMA is changing the normal operation of the memory access cycle in a way that would only affect something fast (like 10ns response) such as a bus buffer. Same thing as this other thread: http://nesdev.com/bbs/viewtopic.php?t=6212

So, I don't know the problem, or the fix, but the work-around is to use series resistors on the data bus. The NES PowerPak seemed to have ran into a similar issue. I don't think resistors don't fix the problem, but rather they prevent a bus conflict from becoming the problem.

2600 wrote:
The 5v tolerant part doesn't bother me as much as the lack of pull-ups on the data bus. If pull-ups were allowed, this wouldn't even be an issue.

Do you mean the PRG data bus? Why are pull-ups needed? If it's 8 resistors or so to put on the board, that's not too bad (assuming the CPLD upgrade is worth it, I'm not familiar with the differences).