In Emulators / NES ROMs

Hi, I have a technical question related to NES emulation and this is one of the only major forums I could find related to the topic. If any of you know the answer or could point me to a more appropriate place to search for the answer, I'd be indebted.

When a write to memory location $4014 occurs, the NES copies 256 bytes from memory to SPR-RAM. I was wondering whether this suspends normal processing for the time this takes, or does this occur in the background. Additionally, are interrupts processed during this period, are they ignored, or are they delayed till the copy is finished?

Most emulator sources I've looked at seem to take the suspends processing/interrupts delayed approach, although given their cryptic nature I can't be sure. Technical documentation that I've found is vague.

Thanks in advance.

Way over my head, but I can point you to There's also an IRC channel on EFnet, channel #nesdev

Thanks, I managed to get an answer out of someone. That site will definitely come in handy though.