Clock rate
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NTSC/PAL differences
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 | 1/3 PPU clock speed | 1/3.2 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.
