Re: Zip Chip programming info / disk image?

["David Wilson" <mcs6502@gmail.com>]

> >then maintain slow mode for a heuristically determined
> >50-or-so milliseconds after a slow slot /DEVSEL reference.

> So the access to the $C600 would tell the
> CPU to slow down, and the timing loops that
> access the hardware will take a maximum
> of ~50ms ?

Accessing $C6xx causes /IOSEL #6 to assert. /DEVSEL #6 is $C0Ex and
this is what is used to detect when to slow down (after all, once the
Apple II is booted the $C6xx code never gets used again). I seem to
recall that the IIgs is clever enough to detect when the motor on
signal of a 5.25" drive is turned on and only slows down then.

Provided the loops keep accessing the Disk ][ registers the system will
remain in slow mode. 50ms after the last access it speeds up again.