Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!mit-eddie!uw-beaver!zephyr.ens.tek.com!tektronix!sequent!jjb From: jjb@sequent.UUCP (Jeff Berkowitz) Newsgroups: comp.arch Subject: Re: Newly announced Intel chip running at 100 Mhz? Summary: Bell tolls for ECL CPUs Keywords: ECL Message-ID: <49426@sequent.UUCP> Date: 28 Dec 90 18:55:47 GMT References: <19256@netcom.UUCP> <19470@netcom.UUCP> Reply-To: jjb@eng3.UUCP (Jeff Berkowitz) Organization: Sequent Computer Systems, Inc. Lines: 30 In article <19470@netcom.UUCP> feustel@netcom.UUCP (David Feustel) writes: >Intel almost had a deal set with PRIME to produce a 100 Mhz ECL 486, >but it was scuttled by the attempted takeover of PRIME by MAI Basic 4. With all due respect to the business problems at Prime, I don't think that's the only reason. The Intel ISSCC paper about the 100Mhz CMOS '486 pretty much sums up the situation with ECL CPU implementations. At any point in time during the last few years, it's been possible to build and ECL CPU which is faster than an MOS implementation. But the ECL guys never seem to get one full product generation (24 - 36 months) ahead; it's always more like 12 to 18 months. Taken together with the higher product cost of the ECL implementation, the end result is that the ECL products can never quite justify themselves in the marketplace. This applies equally to RISCs like the MIPS processor, CISCs like the 486, whatever. This situation will not change, for two reasons. First, MOS will tend to converge on ECL speeds as the transistors continue to get smaller; second, the lower density of ECL will force the ECL implementations to pay off-chip delays to reach functional units that would be on the same chip in an MOS implementation. The significant ECL advantage of low edge rates (relative to frequency) will be addressed by 3.3v MOS parts with carefully designed pad drivers featuring controlled slew rates; designers have learned the lessons of 74F and schottky PALs, and won't repeat those mistakes. -- Jeff Berkowitz N6QOM uunet!sequent!jjb | Bugs are God's way of saying Sequent Computer Systems jjb@sequent.com | you have too much free time.