Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!rutgers!cbmvax!daveh From: daveh@cbmvax.commodore.com (Dave Haynie) Newsgroups: comp.sys.amiga.hardware Subject: Re: (B) 68040 vs. gfx coprocessor Message-ID: <9586@cbmvax.commodore.com> Date: 2 Feb 90 22:23:58 GMT References: <633@xdos.UUCP> <3046@pur-phy> Reply-To: daveh@cbmvax.cbm.commodore.com (Dave Haynie) Organization: Commodore, West Chester, PA Lines: 57 In article <3046@pur-phy> murphy@newton.physics.purdue.edu.UUCP (William J. Murphy) writes: >In article <633@xdos.UUCP> doug@xdos.UUCP (Doug Merritt) writes: >>So the question: would it make more sense for a future Amiga to use >>a general purpose processor rather than a special purpose blitter chip? That really depends on a large number of things. A second '040 might outdo any 32 bit blitter in real clever graphics things, but it would add a considerable amount of cost. It doesn't replace the basic Denise or Paula functions, nor does it completely replace Agnus. So cost-wise, the answer is (currently at least) a resounding NO I would think. Perhaps a low cost general purpose CPU would look more attractive. It would be necessary to emulate the Agnus registers in any replacement unless you want to tack on a big pile of software enhancement costs, delays, etc. >Since so many workstations and graphics coprocessor cards seem to use >the TI DSP chips, why pay the extra cost to have an 040 replace the blitter? Well, they actually use the TI 320 family graphics processors, which are reasonably general purpose CPUs optimized for graphics processing. The 16 bit version of this is on the Amiga graphics card being worked on by Rich Miner's group at the University of Lowell. A chip like this can currently do lots of display stuff that would require a far more expensive general CPU. TI also makes other interesting CPUish chips, like DSPs, but they're something entirely different. You wouldn't pick a DSP as a blitter replacement, most are probably less well equipped at handling bit-aligned operations than some general purpose CPU. But if you did lots of image or sound processing on that nice graphics display, a good DSP would certainly be something nice to have around. >would you suggest that they be true coprocessors? Gee this could be like a >miny CRAY Y-MP. Let's put four 040's in so we can do some awesome Audio >synthesis calculations as well. I think the Crays use symmetric homogeneous multiprocessing, whereas the image that blitters, graphics and DSP chips conjure up is more a "pick the right CPU for the right job" deal. I think both approaches have their merits, though the latter certainly makes it easier on the software folks. >Sorry, don't want to make this thread too silly. I would just like to know >why not use a DSP chip liek the NeXT does? The NeXT does all its video display work with the 68030, which is one reason the display is so slow. They really should have had a separate CPU acting as a Display Postscript engine. The next NeXT probably will; an imaging model like they have is perfect for this, since it places no constraints on what type of CPU is required to execute such imaging commands (eg, no blitter registers to be compatible with). It certainly DOES require more horsepower than what's in your average Amiga to be at all usable, however. > Bill Murphy murphy@newton.physics.purdue.edu >Enjoying my Amiga 2000, but holding out for a real computer: The Amiga 3000!! -- Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy Too much of everything is just enough