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"If rendering is enabled..." clarification
http://forums.nesdev.com/viewtopic.php?f=3&t=15708
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Author:  wbrian [ Sun Mar 26, 2017 1:49 pm ]
Post subject:  "If rendering is enabled..." clarification

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

Author:  lidnariq [ Sun Mar 26, 2017 1:51 pm ]
Post subject:  Re: "If rendering is enabled..." clarification

Yes. Forced blanking = when bits 3 and 4 are both clear in PPUMASK.

Author:  wbrian [ Sun Mar 26, 2017 2:53 pm ]
Post subject:  Re: "If rendering is enabled..." clarification

Per https://wiki.nesdev.com/w/index.php/Glossary

Quote:
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?

Author:  lidnariq [ Sun Mar 26, 2017 3:00 pm ]
Post subject:  Re: "If rendering is enabled..." clarification

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.

Author:  tepples [ Sun Mar 26, 2017 3:26 pm ]
Post subject:  Re: "If rendering is enabled..." clarification

I've introduced the concepts of "rendering enabled" and "rendering in progress" in the glossary.

Author:  wbrian [ Sun Mar 26, 2017 3:59 pm ]
Post subject:  Re: "If rendering is enabled..." clarification

Much appreciated! Thanks for the quick responses.

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