Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84 SMI; site sun.uucp Path: utzoo!watmath!clyde!bonnie!akgua!sdcsvax!dcdwest!ittvax!decvax!decwrl!sun!gnu From: gnu@sun.uucp (John Gilmore) Newsgroups: net.micro.68k Subject: 68020 Performance, 68881 info from Dtack Grounded Message-ID: <1843@sun.uucp> Date: Tue, 4-Dec-84 04:11:33 EST Article-I.D.: sun.1843 Posted: Tue Dec 4 04:11:33 1984 Date-Received: Thu, 6-Dec-84 05:17:04 EST Organization: Sun Microsystems, Inc. Lines: 41 Quote without comment from Dtack Grounded, issue #37, Nov/Dec 84, pg 23: 68020 WATCH We have been guilty of overthusiasm in estimating the performance of the 68020. Motorola has now published a fairly detailed performance analysis. When they speak of a 4-1 speed improvement, they are talking about a 16.67MHz 68020 vs an 8MHz 68000, each with no wait state, and code optimized for the 68020. A no-wait-state 16.67MHz 68020 needs, according to Motorola's literature, 90 nsec SYSTEM access time on the RAMs - and that includes the delays of address multiplexers, decoders, buffers, and data buffers. Translation: 68020 systems will have wait states unless you have unlimited DOD-type dollars. What you and we are presumably interested in is the speed improvement using 150nsec DRAM and comparing the 16.67MHz 68020 with the 12.5MHz 68000 - and that looks to be about 2-1 even. The initial sample 68020s run at 12.5MHz so we are looking at less than 2-1. (These figures assume the use of a 32-bit data bus for the 68020.) MATH CHIP STUFF The 68881 has finally seen first silicon; now we will see if Motorola can break the existing record time of 2.5 years between first silicon and a working (production) complex F.P. math chip. We would like to be optimistic, but anybody who 'bets the company' on early arrival of production 68881s would be a fool, considering the historical record. (We DO think Motorola can beat that 2.5 years, but by how much?) --------- PERMISSION IS HEREBY granted to anyone whomever to make unlimited copies of any part or whole of this newsletter provided that a copy of THIS page, with its accompanying subscription information, is included. [Sorry, FNE -- I didn't retype the whole page, just the sub info --gnu] SUBSCRIPTIONS: Beginning with issue #19, subscriptions are $15 for 10 issues in the US and Canada (US funds) or $25 for 10 issues elsewhere. Make the check payable to DTACK GROUNDED. The address is: DTACK GROUNDED 1415 E. McFadden, Ste. F SANTA ANA CA 92705