Date: Tue, 01 Oct 1996 11:03:32 -0700 From: "Michael L. VanLoon -- HeadCandy.com" <michaelv@MindBender.serv.net> To: "Rodney W. Grimes" <rgrimes@gndrsh.aac.dev.com> Cc: narvi@haldjas.folklore.ee, obrien@nuxi.cs.ucdavis.edu, freebsd-hardware@freebsd.org Subject: Re: H/W recommendation Message-ID: <199610011803.LAA18291@MindBender.serv.net> In-Reply-To: Your message of Tue, 01 Oct 96 09:08:50 -0700. <199610011608.JAA19605@GndRsh.aac.dev.com>
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>> Even Memory PCI bus >> Multiple bus speed speed >> MHz MHz MHz >> -------- --------- ------- >> 33.3 66.67 33.3 >> 30.0 60.00 30.0 >> 25.0 50.00 25.0 >If you guys are going to talk about this at least get the FACTS right >before you make 3 or 4 erronious posts... I have all the FACTS right -- I know exactly what I am talking about. I typo'd the original post (when I accidentally typed PCI where I meant memory bus), which is different from not getting the "facts" right. >``Even multiplier misses >the fact that there are 1.5, and 2.5 multipliers!!!''. I never once mentioned the word "multiplier". I did not discuss the motherboard clock multiplier setting. I discussed multiples of a value. 100 is an even multiple of 33 1/3. It's true that a 100MHz Pentium generally runs at 1.5 * 66 2/3 MHz, but that's not what I was discussing. The original post specifically asked about chip speeds and bus speeds, not multiplier settings. >Memory bus >speed should generally not be specified with 2 digits beyond the >decimal point as it depends heavely on the clock chip and/or oscillator >used in a design. I was specifically trying to make a general observation. That's why the first time I wrote the numbers, I wrote "33 1/3" and "66 2/3". Unfortunately, it's very awkward to write fractions in ascii test, especially when following them by a unit, such as "MHz". So, I used 33.33 and 66.67 to approximate 33 1/3 and 66 2/3. Moreover, if those aren't fairly close to the real figure, and we're truly talking about 33 and 66MHz, then we're also talking about 132MHz, 165MHz, and 198-199MHz Pentiums. I doubt there are any decent motherboard manufacturers out there really doing something stupid like that. Using "166" and "133" is merely a convenient way for them to say "133 1/3" and "166 2/3". >Here, express it the way that most motherboard documents do: That's fine. Very nice table, but not as summary-oriented as I had attempted to be. I figured if they wanted multiplier settings for their motherboard, it would be just as easy for them to look it up in their motherboard's manual, as to read it here. >Rated External Clock External to PCI Bus > CPU and Memory Bus Internal Clock Clock > MHZ MHZ** Multiplier MHZ > > 75 50 1.5 25 > 90 60 1.5 30 > 100 50* 2 25 > 100 66 1.5 33 > 120 60 2 30 > 133 66 2 33 > 150 60 2.5 30 > 166 66 2.5 33 > 180 60 3 30 > 200 66 3 33 > >* The Pentium 100 can be run at either 50MHz external clock with a > multiplier of 2 or 66MHz and a multiplier of 1.5. True, it CAN be, but I'd feel sorry for the fool who bought such a machine. >** 66 Mhz may actually be 66.667 MHz, but don't assume so. See above... >As can be seen the best parts to be using are the 100, 133, 166 and 200, >with the exception that at a mulitplier of 3 the CPU starves for memory. Yes, it's been said that the P5/200 runs barely faster than a P5/166 in many benchmarks, because the bus is saturated. ----------------------------------------------------------------------------- Michael L. VanLoon michaelv@MindBender.serv.net --< Free your mind and your machine -- NetBSD free un*x >-- NetBSD working ports: 386+PC, Mac 68k, Amiga, Atari 68k, HP300, Sun3, Sun4/4c/4m, DEC MIPS, DEC Alpha, PC532, VAX, MVME68k, arm32... NetBSD ports in progress: PICA, others... -----------------------------------------------------------------------------
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