sicklittlemonkey wrote:
On Mar 18, 4:20 pm, "Michael J. Mahon" <mjma...@aol.com> wrote:I think AppleWin may work on the PC, but if it accelerates the "virtual video" as it accelerates the processor, then it may not. All the reasonable uses I can think of for video sensing and VBL sensing are related to an absolute time base, and should not be subject to acceleration (just as it is not in a real Apple II), but I'm not sure that emulator writers agree...AppleWin, probably like most emulators, accelerates the CPU by running the whole machine at a faster clock. That includes the bus and therefore memory reads - which in the case of floating bus reads would mean software-percieved accelerated video generation. Even if video rendering is decoupled from the accelerated emulation, the floating bus reads would be accelerated and not suitable for your purposes.
So, this is actually an emulation bug. If we assume that the emulator is supposed to emulate an Apple II with an accelerated *processor*, then the emulated cycle count should be divided by the acceleration ratio before being used to compute the current "phantom" video byte. As it is, it emulates an Apple II with both the processor and the video refresh accelerated--and there is no such beast!
What I'd like to know is which emulators *do* keep the emulated video period at 1/60th second (or 1/50th for PAL ;-).Again, Virtual ][ is the only other one that I know of.
I wonder how widely used it is--and on which platform? (I've never used it.) -michael NadaPong: Network game demo for Apple II computers! Home page: http://members.aol.com/MJMahon/ "The wastebasket is our most important design tool--and it's seriously underused."