Re: Apple emulators that support "floating bus" video sensing?

[Dirk Thierbach <dthierbach@usenet.arcornews.de>]

Michael J. Mahon <mjmahon@aol.com> wrote:
> Well, the consequence is that any program using animation needs
> to run at 1MHz emulated speed.  This is not the case for an
> accelerated machine.

No. The consequence is that any program using animation needs to
*think* that it runs on 1MHz speed. Because most, if not all Apple
programs do. There's no hardware I know of in the original Apple that
would allow it to check if it runs on an accelerated processor.

But if there happen to be such programs, and the did indeed use a
video-refresh cycle vs. internal speed check to find out at which speed
they ran on an accelerated machine, then one could of course cater
for these programs in the emulator and just let the frame-buffer
refresh and floating bus run at 30Hz relative to real-time. 

No big deal, but it would break most programs that actually use the
vapourlock in the way it was described in the other thread. As these
programs would break on an Apple with a hardware-accelerated processor.

> Oh, well--I hoped I had found a way to combine fast game computation
> with correct-speed animation and delays.  Apparently not for emulators.

> Most accelerators went to some lengths to achieve implementation of
> processor acceleration combined with standard speed sound and (if
> needed) disk access.  

So how did they do that?

- Dirk