RE: [stella] Newbie question emulation

Subject: RE: [stella] Newbie question emulation
From: "Lee Fastenau" <stella@xxxxxxxxxxxxxxx>
Date: Wed, 2 Mar 2005 09:24:58 -0500
> Saying that, do u think a master system or other such system would be
> easier
> for a first attempt? I wanted to do the 2600 because is appeared to be a
> very simple platform, the idea of dirty tricks scares me..

The platform really is simple, but certain aspects of the emulation perhaps
need more precision compared to other emulators.  One reason for this is
that the Atari has virtually no video memory.  It has player, missile, ball,
and background registers, but to effectively display these things, you must
time your changes to these objects down to the CPU cycle.  

As Atari 2600 programmers, we have to baby sit the 2600 through the display
of every scanline.  And because each scanline takes exactly 76 CPU cycles to
render, there's not much time to change the registers I mentioned above
before the electron gun in the television shifts down to the next scanline.
So as an emulator programmer, you would essentially have to emulate the way
the electron gun in a television works, where on other consoles you'd just
blit a big chunk of video memory to the computer screen.  (Yes,
oversimplified, I know.)

So it's actually due to the simplicity of the hardware that coding (both
2600 games and emulators) becomes more of a challenge, which I think is one
of the many reasons we enjoy programming the 2600 so much.

There may be other forums with more of an emulator focus that may be able to
shed more light on the subject.


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