Clock rate: Difference between revisions

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(added divide values for CPU clock speed)
Line 7: Line 7:
| PPU clock speed || 21.477272MHz / 4 || 26.601712MHz / 5
| PPU clock speed || 21.477272MHz / 4 || 26.601712MHz / 5
|-
|-
| Corresponding CPU clock speed || 1/3 PPU clock speed || 1/3.2 PPU clock speed
| Corresponding CPU clock speed || 21.47MHz / 12 = 1.78977267 MHz = 1/3 PPU clock speed || 26.601712 MHz /16 = 1.662607 MHz = 5/16 PPU clock speed
|-
|-
| Height of picture || 240 scanlines || 240 scanlines
| Height of picture || 240 scanlines || 240 scanlines

Revision as of 15:00, 3 March 2010

Consoles in the USA and Europe run at different speeds due to the different television standards used. The main differences between the NTSC and PAL PPUs is as follows:

Property NTSC PAL
Master clock speed 21.477272MHz
= 236.25 MHz / 11
26.601712MHz
PPU clock speed 21.477272MHz / 4 26.601712MHz / 5
Corresponding CPU clock speed 21.47MHz / 12 = 1.78977267 MHz = 1/3 PPU clock speed 26.601712 MHz /16 = 1.662607 MHz = 5/16 PPU clock speed
Height of picture 240 scanlines 240 scanlines
Nominal visible picture height
(see Overscan)
224 scanlines 268 scanlines
Length of VBLANK 20 scanlines 70 scanlines
Timing quirks First scanline is one PPU cycle shorter during every other frame None

Other than these differences (and video output), the NTSC and PAL PPUs function exactly the same.