Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83; site amd70.UUCP Path: utzoo!watmath!clyde!floyd!harpo!eagle!allegra!amd70!phil From: phil@amd70.UUCP (Phil Ngai) Newsgroups: net.micro.68k,net.micro.16k Subject: Re: 68020 vs 16k Message-ID: <4313@amd70.UUCP> Date: Thu, 9-Feb-84 15:23:50 EST Article-I.D.: amd70.4313 Posted: Thu Feb 9 15:23:50 1984 Date-Received: Fri, 10-Feb-84 07:12:57 EST References: <1646@rocksvax.UUCP> Organization: AMD, Santa Clara, CA Lines: 28 I can't let this one go by. Intel, feel free to respond also. > Beware of the benchmarks that sound real impressive, but require you > to use VERY fast memory to acheive as I have heard about some of the > faster versions of the 286 (not a put down on Intel, but their sales > lit which seems to always compare benchmarks is on CPU's often has > looked real good on paper, but has not turned out the same in a system). > Norm Zeck The 286 does not require VERY fast memory, at least, for a given memory bandwidth, the 286 will run with slower access memories than the 68000 will. The 286 has a separate address and data bus, just like the 68000. However, they do something useful with it. They overlap the data operation of the current cycle with the address of the next cycle. For example, with an 8 MHz 286, a word is required every 250 nS. However, the required memory access time is a leisurely 242 nS. To run a 68000 with an 8 megabyte per second memory bandwidth would require a 16 MHz 68000. The required memory access time in that case would be about 156 nS (address strobe in state 2, data required end of state 6, 5 states * 31.25 nS per state = 156.25 nS). Of course, if you have 156 nS, you probably need 100 nS DRAMs. This is expensive. Perhaps intelca!kds could comment on my analysis. -- Phil Ngai (408) 988-7777 {ucbvax,decwrl,ihnp4,allegra,intelca}!amd70!phil