At 04:14 PM 3/3/99 -0500, you wrote:
>What Atari games used the 2600 style hardware? I have looked a a good
number of the early Atari arcades games during my work on MAME and have not
seen any yet that work that way.
I don't think MAME emulates the games that are closest to the 2600 in
archetecture.
>There are either all discrete logic like Pong, or they are basic tile and
sprite systems with custom logic thrown in to do scalling and such.
The designers said that the way (in actual electronic components inside the
TIA) that the 2600 generates its sprites was similar to the early coinops,
but made generalizable.
If you look at the motherboard of Space Race, you will see the actual
shapes of the ships as diodes or resistors in a V pattern which, through
analog logic, delay the signals in such a way as to generate that shape on
the screen. This is a very minimalistic design philosophy of doing as much
as possible through cheap tricks with a minimum number of gates, and if a
CPU is involved, a minimum amount of memory usage.
For instance, the width registers on the 2600 involve delaying the signal
as the beam is drawn. The color involves delays on the composite video
signal. Very simple but effective stuff. Look at the way the 2600
generates its playfield as well, by using almost no memory. You take a lot
of those cheap tricks, have them look at a tiny piece of memory instead of
being hardwired, and you collapse them into a VLSI chip, and drive it with
a CPU, and that's what the VCS seems to be.
This is the opposite of traditional computer archetectures that implement a
straightforward framebuffer and software blit everything (like the
Astrocade), or use standard OS/BIOS calls to the sprites which involve some
limitations (Intellivision). The 2600 is able to animate sprites faster
than most machines of its era because it talks directly with the video
signal every scanline. That, plus being able to shift color registers
every scanline is an advantage over systems that use either a fixed color
palette (Intellivision) or having to select 4 or 5 color registers per
screen (Astrocade).
If you've ever opened up an Astrocade you'd see what I mean. In 1977,
implementing a framebuffer archetecture involved a lot of silicon, and as
stated above, for action gaming, it wasn't even that effective. The 2600
has almost no silicon but can generate extremely colorful, kinetic displays.
=========================================================
== Glenn Saunders --3D Graphics / Videography / Web development-- ==
== krishna@xxxxxxxxxxxxxxx http://www.geocities.com/Hollywood/1698 ==
== Stella@20 video page http://users.cnmnetwork.com/~krishna
==
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