Search found 4 matches

by RobertLoggia
Sun Apr 26, 2015 8:46 pm
Forum: NESemdev
Topic: CPU and PPU clock math
Replies: 6
Views: 3843

Re: CPU and PPU clock math

Also note that the real clock frequency is never exactly what is advertised, for example on the 21.47 MHz clock you can see a +-40 Hz tolerance in the page you linked. If theres a +- 40Hz tolerance, then why is it important to care about being 1 PPU cycle short when its an odd frame. Wouldn't it no...
by RobertLoggia
Sun Apr 26, 2015 6:28 pm
Forum: NESemdev
Topic: CPU and PPU clock math
Replies: 6
Views: 3843

CPU and PPU clock math

I've read[1] that the NES PPU (NTSC/2C02) is 3 times the speed of the NES CPU. According to the wiki: The NES CPU operates at a speed of 21.477272 MHz / 12 = 1789773Hz. The NES PPU operates at a speed of 21.477272 MHz / 4 = 5369318Hz. If we take the CPU speed and run the "3 times slower than th...
by RobertLoggia
Sat Apr 18, 2015 7:46 pm
Forum: NESemdev
Topic: Render per pixel, scanline, or frame?
Replies: 3
Views: 1881

Render per pixel, scanline, or frame?

Is it realistic for an emulator to be coded such that each pixel is rendered to the screen? I'm coding up an emulator in SDL and finding that my computer, a modern i7, is struggling to render per pixel. Do most emulators actually render per pixel, scanline, or frame? I'm just figuring, if its per pi...
by RobertLoggia
Sun Apr 05, 2015 7:21 am
Forum: NESemdev
Topic: Stuck on PPU Implementation
Replies: 17
Views: 10972

Stuck on PPU Implementation

I just finished writing my CPU and tested it against Klaus' 6502 test program. Everything works except BCD mode. I'm now starting to write the PPU. The CPU seems like a walk in the park compared to what I'm trying to grok on the nesdev wiki. What's a great/easy ROM for testing while programming the ...