Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!cbmvax!daveh From: daveh@cbmvax.commodore.com (Dave Haynie) Newsgroups: comp.sys.amiga.advocacy Subject: Re: The 68050 - end of the 680x0? (was Re: The Amiga's Future) Message-ID: <22522@cbmvax.commodore.com> Date: 17 Jun 91 23:17:37 GMT References: <5068@orbit.cts.com> <16647@darkstar.ucsc.edu> < <1308@cbmger.UUCP> <28@ryptyde.UUCP> > <01dH!cmr@cs.psu.edu> <1991Jun10.072945.8821@neon.Stanford.EDU> <22365@cbmvax.commodore.com> <1135@stewart.UUCP> Reply-To: daveh@cbmvax.commodore.com (Dave Haynie) Organization: Commodore, West Chester, PA Lines: 100 In article <1135@stewart.UUCP> jerry@stewart.UUCP (Jerry Shekhel) writes: >daveh@cbmvax.commodore.com (Dave Haynie) writes: >>Since the leap from 68030 to 68040 was greater than the leap >>from 80386 to 80486, it sure looks like Motorola's in the lead >What the hell are you talking about? I am taking about microprocessor architecture. You are, apparently, looking a little bit at feature lists. >The "leaps" in both product lines were exactly the same (on-board FPU, True, they both have on-board FPUs with similar functionality. The '040 FPU design is more sophisticated, more like a RISC FPU, which is why its instructions execute in considerably fewer instructions. The latest external FPUs, 68882 versus 80387, were essentially on a par. Therefore, I consider Motorola to have made a much greater leap in this area. >cache, The 80486 cache is a single unified, write-through cache. A single MMU to go along with it, with a small TLB. The '040 has separate I and D caches which operate in parallel, with write-through or snoopable copyback, and large TLBs. Therefore, I consider Motorola to to have made a greater leap in this area. >Why do all of you Amigoids have it etched upon your brains that Motorola is, >was, and always will be "clearly superior"? I'm not saying anything peculiar to "Amigoid", or, in fact, anything that hasn't been said outside the "fans of Intel" segment of the industry. Intel has no choice but be "clearly inferior"; they can't change anything that will cause MS-DOS to fail, regardless of the existence of any available technology that can be easily assimilated into the Intel architecture that could speed up the operating of UNIX or OS/2. The unified cache is an obvious example of this -- Intel's even using split caches themselves in their other chips, because they simply result in better performance. >>Intel has been pushing the idea of using an i860 as a coprocessor, despite >>the fact it's not all that well suited to the job >Sorry Dave. The i860 is EXTREMELY well-suited to the job of a coprocessor, >for graphics or floating point. Sorry Jerry, it isn't. The fact that the i860's data cache operates only in copy-back mode, and provides no snooping mechanisms, make it ill suited for use as a coprocessor, since all cache consistency must be handled in software alone, that's a significant performance hit. Both of these problems are apparently cured in the new chip. >I cannot believe the ride they're offering customers now, with their >486SX/487SX processors. OK, I can accept the idea of the 486SX, for those >people who don't need the FPU or cannot afford the full 486. Yet, the 486SX, at least presently, costs the same to make as the 486, since it's the same die. They're selling, as always, based on their captive market. >But pricing the 487SX as a coprocessor (big bucks) is really sleazy, >considering it is nothing more than a full 486 repackaged with an extra pin >that turns off the 486SX. I don't see it as being any different. They're doing this one because Intel only offers single piece pricing on their coprocessors, so they make a mint on them. You don't really think a $500 '387 costs that much more to make than a $50 '882 offering Morotola systems similar FPU performance, do you? Intel just likes to sell them to end-users themselves, rather than pricing them in a range systems houses can afford to include in every unit. Strangely enough, that's spawned the creation of Weitek math chips with Intel bus pinouts. Weitek cancelled the 68030 version because nearly every '030 system ever made came with a 6888x chip (at least at the time). >MS-DOS is truly "braindead", but the '486 is not. The '486, in its native mode, isn't really that great a 32 bit processor, but it isn't bad. The architectural baggage it carries around necessary to support MS-DOS and 8086 emulation modes is what makes it ugly. The unified cache without copyback, the simplified MMU, various other architectural details make the '486 inferior to any other 32 bit processor of this generation. Which is why so many '486s are sold into PC Clones, those that go elsewhere are virtually insignificant. A few very companies pick the '486 for use outside the PC Clone market (other than Intel), and that's usually because they're running software developed on the PC. Look anywhere else, you'll see 680x0s, 29Ks, R3000s, SPARCs, maybe even an ARM or a Transputer occasionally. People use '486s because the run MS-DOS. >Show me that you can do more, Dave, than post the same old ignorant Amigoid >ramblings full of BS phrases like "braindead". Sure seems to me that you're the one not supplying any information. If I say "it is", you can sure say "it isn't". But when you ask me to supply fact to back my points without supplying any yourself, you're the one who's going to come out looking foolish. >| JERRY J. SHEKHEL | POLYGEN CORPORATION | When I was young, I had to walk | -- Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy "This is my mistake. Let me make it good." -R.E.M.