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PPU (PAL) clock & video

A project log for Playing with a PPU (UA6538)

Experimenting to evaluate a NES PPU (clone) as VDP for the MRC6502

padnestpadnest 02/21/2022 at 11:010 Comments

PPU requires a clock signal input at pin 18 and for the UA6538 it must have a frequency of 26.601712 Mhz because it's a PAL chip.

I don't know what are the clock signal input specifications so I'm trying to use this simple clock generator circuit:

I'm getting just 2.2 Vpp oscillation but it seems to be ok for the PPU:

The PPU video output cannot be connectd directly to the TV low impedance AV input: we need a video buffer circuit like this one:

See you next time!

Ciao!

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