"If rendering is enabled..." clarification

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wbrian
Posts: 11
Joined: Wed Feb 15, 2017 6:41 pm

"If rendering is enabled..." clarification

Post by wbrian »

I've been reading the scrolling docs on the wiki and the phrase "If rendering is enabled..." is encountered a lot. I'm just trying to clarify what it means for rendering to be considered "enabled."

I'm interpreting it as:

- Either bit 3 or 4 is set on PPUMASK
- Not in Vlank or Forced blank

Am I correct here? The first bullet point is the thing I'm least sure of.

Thanks in advance,

Brian
lidnariq
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Re: "If rendering is enabled..." clarification

Post by lidnariq »

Yes. Forced blanking = when bits 3 and 4 are both clear in PPUMASK.
wbrian
Posts: 11
Joined: Wed Feb 15, 2017 6:41 pm

Re: "If rendering is enabled..." clarification

Post by wbrian »

Per https://wiki.nesdev.com/w/index.php/Glossary
Forced blanking
Turning off the rendering circuitry by writing zero to $2001, giving the CPU the same access to VRAM through the PPU ports that the CPU normally has during vertical blanking.
I guess this is where I'm getting confused since it implies that every bit is clear during forced blanking. So more accurately, forced blanking occurs when bits 3 and 4 are clear?
lidnariq
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Re: "If rendering is enabled..." clarification

Post by lidnariq »

Yeah. The other bits in PPUMASK don't the rendering/evaluation process.

I/someone should fix the glossary, but I'm having trouble with phrasing.
tepples
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Re: "If rendering is enabled..." clarification

Post by tepples »

I've introduced the concepts of "rendering enabled" and "rendering in progress" in the glossary.
wbrian
Posts: 11
Joined: Wed Feb 15, 2017 6:41 pm

Re: "If rendering is enabled..." clarification

Post by wbrian »

Much appreciated! Thanks for the quick responses.
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