Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!elroy.jpl.nasa.gov!ncar!gatech!rutgers!cbmvax!daveh From: daveh@cbmvax.commodore.com (Dave Haynie) Newsgroups: comp.sys.amiga.hardware Subject: Re: Amiga Custom Chips - why hasn't C= made them faster? Message-ID: <20298@cbmvax.commodore.com> Date: 2 Apr 91 22:18:09 GMT References: Reply-To: daveh@cbmvax.commodore.com (Dave Haynie) Organization: Commodore, West Chester, PA Lines: 34 In article cpetterb@glacier.sim.es.com (Cary Petterborg) writes: >The Amiga has been out for years now. There have been improvements >made to the custom chips, Agnus in particular. But, I am amazed at >the fact that their clock speed, etc. has remained the same. In an >industry where last years chip runs twice as fast this year, C= sure >has sat back on their b*tts as far as performance is concerned. Is >it because they aren't willing to invest any more money into the >technology because they can sell so many A500's as they are now? >What gives? Certainly the technology exists to speed them up. Well, yes and no. First of all, you're confusing two problems. CPU speedup have been going on for quite some time. But that's pretty independent of the rest of the world. And it doesn't generally take lateral leaps. For example, Motorola would have had a faster 68000 much sooner than the 68020 if all they did was convert the 68000 over to high speed CMOS. But not soon enough to not go ahead with the more advanced 68020 architecture. That's pretty typical of the industry. Specific to the Amiga, there were several problems. First of all, the video chips are directly tied to video. If you speed up the bus cycle, you speed up the video shift rate, unless you go to a multiple of it. The current Agnus runs a 280ns cycle. To double that, and go to 140ns, you would need 60ns DRAM, which are only now becoming available in large quantities, and are still quite expensive (though, if they're on schedule, they'll get cheap in the next year or so). Any somewhat faster bus speedup and you lose NTSC or VGA scan and pixel rates. While it's conceivable that you could divorce the scan rate from the bus rate, that's a MAJOR architectural change, far more complex than building new chips that speed up in other ways (32 bit bus is the way the microprocessors gained their modern speed, more than clock rate speedups). -- Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy "That's me in the corner, that's me in the spotlight" -R.E.M.