Re: 264 series questions

From: Levente Hársfalvi (
Date: 1999-10-06 18:15:02


> I already wondered how a SID behaves if clocked with the strange Phi2
> signal.
> If the divided MUX signal and the Phi2 signal are in phase, and the SID
> chip select signal is gated with Phi2, it should work without any
> problems. But without gating the chip select I almost can't believe it.

I don't know if it's gated; the CS' logic is programmed into a GAL and I
really don't know if it pays attention to sync with Phi2.

> Then probably a 6522 (probably only with some tweaking like in the C64)
> and 6526 should also work, but perhaps with broken timers. ...

Finally, I found a more obvious example that could be examined easier.
This is the interface plug of the 1551 floppy drive. It is in fact a
small interface card that connects to the expansion port, with a 6523
TIA that handles all tasks of data communication. The firm should have
also solved problems (if occured) when designing this board.


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