On 2012-09-12, at 22:35, Gerrit Heitsch wrote: >>>> It should be easy to come up with a circuit that does the same thing, take the crystal clock and divide by 2.25 (for PAL). The 8701 does that by doubling and then dividing by 4.5 (PAL). >>> >>> Note it doesn't actually divide by 4.5; it divides unevenly. The >>> datasheet shows how exactly (we have checked it with pictures of >>> the die, it does what the datasheet says). >> >> What does this exactly/practically mean? Will it matter if I somehow divide the xtal just by 2.25? Does one have to care about the relation of the phases of both outputs? >> > > There was some reason why they didn't use 2 crystals in the C64 but had to have the color clock and the dot clock be related to each other. Which is exactly what I expect, but this makes it even more complicated than already non-completely-trivial task of dividing frequency by fractional values, doesn't it? -- SD! Message was sent through the cbm-hackers mailing listReceived on 2012-09-12 22:00:06
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