Fx3 wrote:
- During a sprite DMA transfer (4014h), does the PPU run?
The PPU is unaffected. All $4014 does is copy bytes to $2004.
Quote:
Can IRQs/NMI be requested/triggered during this period?
Yes and no.
Yes, NMIs and IRQs still happen as normal. But the CPU is effectively "stalled" until the DMA is complete. So any NMI/IRQ that occurs during DMA won't occur until an instruction after the DMA is complete. Example:
Code:
STA $4014 ; if IRQ occurs during DMA
LDA $8000
; IRQ happens here
Quote:
What cycle and line does the PPU render its first visible background pixel? And when does it plot into screen?
Cycle 0 of the first rendered scanline.
The NTSC frame:
Code:
--------------------------
1 "idle" scanline
--------------------------
20 scanlines of Vblank
--------------------------
1 "prerender" scanline (same as rendered scanlines, but no pixels output)
--------------------------
240 rendered scanlines
--------------------------
See this doc for details:
http://nesdev.com/2C02%20techn ... erence.TXT