Re: The Perfect Emulator?

["Bryan Parkoff" <nospam@nospam.com>]

Where can I obtain software commerical for testing screen mode flipping?

-- 
Bryan Parkoff
"Holger Picker" <pickerh@uni-muenster.de> wrote in message
Pine.A41.4.44.0309300924510.89898-100000@zivunix.uni-muenster.de">news:Pine.A41.4.44.0309300924510.89898-100000@zivunix.uni-muenster.de...
> On 29 Sep 2003, Michael J. Mahon wrote:
>
> > One of the very few examples of a program which would require this
> > detailed accuracy for correct appearance is a program which uses
> > software to synchronize with the video refresh in order to perform
> > synchronous video mode switches.  Although there are a few demo
> > programs that use this technique, to my knowledge it has never been
> > used in commercially-released software.
>
> I'm sorry, Mr. Mahon, but this technique was actually used by a
> commercially-released software. The game 'Drol' (by Broderbund) shows a
> little animation sequence after level 3, which reads address $c050 for
> synchronization with the display. Some emulators that do not emulate $c050
> properly (mostly the case) or do not simply deliver random values as a
read
> value (like AppleWin does) will hang.
>   Apart from that, most emulators do not properly display the video effect
> which is used during the noise routine found in the games "The Institue"
or
> "Lucifer's Realm". This effect consists of very fast mode flipping (hires
> <-> text) that occurs many times during the display of one video frame.
> Emulators usually emulate just one video mode per video frame (i.e only
> 50/60 mode changes per second).
>   In addition, many emulators (e.g. ApplePC) will almost hang when
> attempting to display the (drawn) monitor sequence found with "Amazon" at
> the beginning of the game. Here, a very fast page flipping (hires 1 <->
> hires2) occurs to create some "noise" ouput of the (drawn) monitor. So
far,
> I know of two AppleII emulators only that provide enough accuracy for an
> almost precise output. The first is written by Mr. Simms for Linux (cycle
> exact emulation), and the other is the Dapple emulator (now called Emu][
at
> dapple.sourceforge.net) by Dosius for DOS or Win9x (line exact emulation).
>
> > Therefore, providing support for this level of cycle-counting accuracy
> > would reduce emulator performance for very little practical gain.
> AFAIK, Mr. Simms' emulator as well as Emu][ use some kind of cache to
reduce
> the amount of video bytes that have to be converted to the host machine's
> display.
> BTW.: Good C64 emulators like VICE or CCS64 have to use a *very* precise
> cycle exact emulation of the VIC in combination with the processor for
many
> programs (especially games). Nevertheless they still run at a sufficient
> speed even on my old PC.
>
> Kindest regards
>
> Holger
>