NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/sys/amiga/hardware-part1/6539

Internet Message Format | 1996-08-05 | 3.3 KB

Path: news.primenet.com!pdtaylor
From: [e-mail] (Daniel L. Taylor)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: Amiga vs. PC
Date: 7 Mar 1996 00:42:02 -0700
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I was going to stay out of this, 'specially since Dave Haynie's usually
the voice of reason, but there's one thing that the Amiga's chip set has
that I consider almost irreplacable, and that's the playfields plus COPPER
combination.  The ability to switch display regions without moving blocks
of raster data around, no matter whether it's bit planes or chunky pixels
(effectively hardware backing store), particularly to/from main memory in
most cases, provides a flexibility that no other "small" computer can
match PERIOD.  My "old" A2500 "redraws" WB foregrounded windows faster
than the 5x6/PCI system that my boss makes me use at work; it doesn't
render text quite as fast within a window, but I can't type or read faster
than the Amiga can present the data, anyway.  Just for numbers, with
a 600 line display, the CPU needs to access 300 ns memory 2400 times, I
think, on the Amiga, to completely change the display.  On a PC, that
would be 120,000 memory accesses, at least, at (generously 90) ns.  CPU
speed has litle do do with these memory moves, and if the PC's blitter
has to fetch from main memory (on those that even can ((though the
Amiga's standard chip sets can't either))) that interferes with the
CPU memory access.  Anyway Amiga 720 us, PC 10.8 ms.  Yes, that's less
than a frame, but since the Amiga multitasks, it can be doing something
else, while the PCs CPU is stuck blitting.  All the Meaningless Informa-
tion Provided by Salesmen (MIPS) in the world aren't useful if they're
just keeping house, rather than working on your application.

The Blitter was nice to have; a "proper" one is still worth having, but
the PCs do have useful ones.  For most users sprite cursors are the best
of them, but for games that lives within the sprite count, they're nice.

The only advantage of the bitplane organization has is that more useful
windows can be opened in the same amount of memory.  If your Amiga has
a 2Mbyte chip RAM AGA and a Mac or PC has 2 Mbyte VRAM, the Amiga can
open more applications, since most are 2 or 4 color, without copying
the window data to/from main memory.  And the ability to have "private"
and "public" screens gives the apps that do need a larger display with
"zero" redraw time (really 1 video frame) when switching around.  I often
have 4 or 5 screens running on my A2500 (WB, a couple of telecoms ((A2232)),
an emacs or two).

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