using the cassette buffer to store data

Basic and Machine Language

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carlsson
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Post by carlsson »

Technically, the VIC-I outputs the following frequencies:

36874 ($900A), freq=(Phi2/256)/(128-(PEEK(36874)+1 AND 127))
36875 ($900B), freq=(Phi2/128)/(128-(PEEK(36875)+1 AND 127))
36876 ($900C), freq=(Phi2/64)/(128-(PEEK(36876)+1 AND 127))

where Phi2 is 4433618/4 Hz for PAL or 14318181/14 Hz for NTSC.

This means that POKE 36874,128 should equal 34 Hz on a PAL machine,
while POKE 36876,253 equals 8659 Hz or something like that.
Anders Carlsson

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