Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!wuarchive!psuvax1!news From: melling@cs.psu.edu (Michael D Mellinger) Newsgroups: comp.sys.amiga.advocacy Subject: Re: Blitter vs. 040 (was: Computer Architecture question Message-ID: Date: 11 May 91 11:28:34 GMT References: <3310.tnews@templar.actrix.gen.nz><1991May9.070349.15151@neon.Stanford.EDU><3496.tnews@templar.actrix.gen.nz> <3602.tnews@templar.actrix.gen.nz> Sender: news@cs.psu.edu (Usenet) Organization: Penn State Computer Science Lines: 77 In-Reply-To: jbickers@templar.actrix.gen.nz's message of 11 May 91 08:54:43 GMT Nntp-Posting-Host: sunws5.sys.cs.psu.edu In article <3602.tnews@templar.actrix.gen.nz> jbickers@templar.actrix.gen.nz (John Bickers) writes: > Hmmm. So, how well can the NeXT perform animation? The 68040 is Who knows, who cares. If you're going to do native animations, do them in color, etc. I would be interested in hearing the results for both the color and monochrome machines. The monochrome NeXT does contain 2-bit gray scale, a million pixels, and alpha channels, so some neat things can be done with it. > definitely faster than 2 68030s. In an 040 A3000 does the blitter Really? Faster than 2 68030s at this sort of memory intensive operation? I'm not sure. Anyone have an 030 and 040 manual handy? There are other factors that come into play though, as someone has already pointed out. The A500 only has a Blitter and the < 1 mip 68000, and it performs great animation. > become a bottleneck. Meaning could things be done faster if the CPU As kdarling points out quite often, things are _already_ done faster if the CPU is used instead. It depends on the kind of animation involved, and for the delta animations (or whatever they are called) the Blitter is next to useless. For some block and line operations too, the Blitter is not useless, but it is slower. Depending on the CPU one happens to have. Let's say the 030. An 040 should be > than the 68000 + blitter. No? What it offers is limited co-processing. So while on an Amiga 3000, say, the CPU might be able to zap an image to the screen faster than the Blitter, the application should perhaps use the Blitter and let the CPU do other important things alongside it. How much does coprocessing matter. Let's say that you can get 10 mips b/w the two of them. A 15 mip 68040 is still going to give you more horsepower(33% more). Some of that might be lost in context switching and for other overhead. How well does the A3000 do animation in its million pixel display mode? That might give us some indication of what the NeXT can do. This doesn't seem to be applicable to delta animations, but it is important when you want to run a line drawing demo alongside a ray tracer, for example. Context switching just needs to be handled properly. Ray tracing for example isn't going to require a lot of blitter time. So, in fact you lose because it can't donate its extra cycles to the ray tracer. I would think the 040 would smoke the blitter/030 combo because you aren't utilizing both Amiga chips to their fullest potential. The 040 Amiga will gain from the blitter that extra time it takes to display a pixel to the screen, but that is small in comparision to the time the actual calculation takes. The same thing applies to all the things that can be offloaded onto coprocessors. A 68040 CPU might process a Postscript file a tad faster than a 68020 laser printer, and the same CPU might pump data through a sound thingo (DAC?) faster than a DMA-driven sound chip, and the same CPU might pump data to/from disk faster than a DMA-driven disk IO chip, and the same CPU might draw to the display faster than a drawing chip, but put them all together... Yes, but if in the next generation machine the power of the CPU is greater than the cumulative power of all the chips in the older machine then you could throw out all of the old chips and replace them by the one chip and get a computer that is just as fast(of course keeping all the chips plus the new CPU would make it even faster). On the NeXT the the I/O and sound are offloaded. The graphics are not of course. -Mike