Re: [stella] Fwd: Some Amiga URLs.
Subject: Re: [stella] Fwd: Some Amiga URLs.|
From: Glenn Saunders <cybpunks2@xxxxxxxxxxxxx>
Date: Sun, 09 Sep 2001 20:58:36 -0700
I tried it on my machine and here's the report.
First off, the manual itself says it's not going to be compatible with a
lot of games. It doesn't support:
-Indirect Jump instructions
-Controllers other than first joystick and paddle
-Mid-frame collision checking
I don't know why these limitations exist...
One thing he says seems rather suspect:
"Unfortunately, emulating the Atari 2600's custom hardware takes up far
more time than emulating its CPU, so the benefits of translation are hardly
This is clearly a failure of vision. The translation also has to occur at
the register-access level, mapping TIA calls to analogous Amiga HW
registers and mini-subroutines which emulate the them.
The Amiga has, I believe, 8 hardware sprites per scanline. I don't know
how wide they can get or whether they can replicate. They are multicolored
which comes in handy. But right there that's enough to simulate 3-copy
sprites and two missiles (sans the ball) without using bitmapped graphics
at all. In cases where the 2600 overlays both sprites the Amiga can just
use one sprite. I also believe that the Amiga sprites are twice as wide as
the Atari's, so in a six-char routine you'd only need 3 sprites. It has
4-voice 8-bit sound hardware which is like a POKEY on steroids which is
like a TIA on steroids. Its copper can change just about anything in mid
screen and even on a lowly A1000 there is enough CPU time to probably do
enough hardware calls in mid-scanline to emulate TIA hw calls, mapping
these to equivalent Amiga alternatives.
It doesn't look like this emulation is attempting to do a
scanline-by-scanline metal-banging approach the way it should. It looks
like it's still building a bitmap each frame the way traditional PC
emulators do it, which is why it requires AGA for the maximum colors per
screen (rather than per scanline) that it will need. This is the
altogether wrong approach on the Amiga which has a graphics system that was
designed for on-the-fly changes per scanline and mid-scanline (i.e.
copperlists, HAM, etc..). Nevertheless, it's certainly the easiest
approach to take if you don't want to get into the intricacies of the
low-level Amiga hardware.
Even worse, the games it says work don't when I try to convert them. I
tried Fantastic Voyage because I couldn't figure out how to concatenate
files to make 2K games 4K games and it failed during translation.
Okie Dokie did run and reportedly at 98% fullspeed. I don't know if it's
an inaccurate counter or what, but assuming it is an accurate count that's
pretty lame that it's still not 100% on a superlowres (320x200) screen with
a largely static display and my system is the very top end as far as 680x0
So I'm not particularly impressed.
The author's name is Neil Cafferkey and if you want to email him:
At 10:46 PM 9/9/2001 -0400, you wrote:
Sorry for responding to myself, but...
I noticed that Bob Colbert's Okie Dokie is part of the Electrostatic
distribution.. Pretty cool (assuming he gave permission :)
Has anyone with an Amiga used this program before? Comments?
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