Re: Hardware musings

[eeastman@gmail.com]

Ed Eastman wrote:
> Lets see, 4us per bit

I just figured out that emulators need a clock advance signal to tell
the hardware how 'fast' they are clocking.  The timer on this device
needs to be guided by the A2 clock pulse in order to be bit accurate in
it's timing.  Rather than have an asynchronous clock in such a device,
there should be some feedback to the device of the clock advance to
allow it to calcualte the rotation of th disk and track seek time
accurately to reproduce synchronized tracks.

Of course this revolation also needs to be applied to the disk II
bitstream emulated in software if you really want copy protected disks
to work.  Of course in the event such a signal is not available or
possible, then real-time emulation should be assumed and have an
asynchronous clock.

Now I'm trying to remeber if this hareware was to hook to a disk II
controller or a PC for emlation.  This clock issue could make it not
totally feasable for both.

Thankx,
Ed