At 08:29 AM 4/26/00 +0200, you wrote:
So... do all the old Amiga games run on your editing workstation?
Ironically, I don't have many commercial Amiga games, although I played
some great shareware games like a truly ass-kicking Galaga redux. I guess
that gives me something to look forward to as a hobby down the road. Most
of the games were written for OS 1.3 which is vastly different from even OS
2.1, let alone 3.x. Most of the incompatibilities rest there, which is why
people came up with software degraders and hardware multi OS ROM boards.
The other incompatibilities come from OCS/ECS chipset games that write
directly to the registers instead of the alias (I guess you could call
them) registers. When the underlying hardware registers changed with the
AGA chipset (really the final evolution of the Jay Miner style of graphics,
BTW) a lot of games broke as well.
However, on my Amiga 2000 with an 040/28 in it and an Amiga 1200 030/50 I
ran Wing Commander just fine.
The kind of thing you'd expect to see, massive speedup problems, really
doesn't seem to be an issue with Amiga games. They apparently time
themselves differently from other platforms. So I don't think the dual
clocking is that much of a problem. It certainly doesn't hurt
compatibility with non-game software. Even in the early days they had
non-Chip-Ram RAM expansions, so I think they always had a way to
distinguish between chip RAM and expansion RAM at the OS level, it just
took a while before there were accellerators available.
The question is also at which rate the memory can be accessed. On the
original Amiga, though the CPU runs at 7.16 MHz, bus speed is also half of
that, and half of the bus cycles are reserved to the video and other
Yeah, the Amiga is like the SGI's unified memory architecture, only with a
really slow bus (by today's standards). As one operation starts to
monopolize the bus, the rest of the system gets starved, which is why its
so easy to lose bytes on a high speed modem connection to the stock serial
port when running in ANSI color.
I think video DMA on the Atari cuts raw throughput of the CPU down by
1/3rd, which is why there is a poke you can do to turn off video DMA when
you are running a big numbercrunch operation. A lot of Atari BBS operators
would do that. The Atari 1200XL had that assigned to one of its function keys.
It actually cuts throughput enough to hinder playing digital samples,
actually, which is why sampling programs (or software voice synths like
SAM) would blank the screen.
Glenn Saunders - Producer - Cyberpunks Entertainment
Personal homepage: http://www.geocities.com/Hollywood/1698
Cyberpunks Entertainment: http://cyberpunks.uni.cc
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