Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/3/84; site cfa.UUCP Path: utzoo!watmath!clyde!burl!ulysses!allegra!mit-eddie!genrad!panda!talcott!wjh12!cfa!ward From: ward@cfa.UUCP (Steve Ward) Newsgroups: net.micro,net.micro.68k,net.micro.16k Subject: Floating Point Comparisons Message-ID: <133@cfa.UUCP> Date: Tue, 26-Mar-85 19:41:02 EST Article-I.D.: cfa.133 Posted: Tue Mar 26 19:41:02 1985 Date-Received: Thu, 28-Mar-85 02:09:04 EST Distribution: net Organization: Harvard-Smithsonian Center for Astrophysics Lines: 91 Xref: watmath net.micro:9845 net.micro.68k:693 net.micro.16k:301 The purpose of providing this information is to inform, not to promote a particular manufacturer, computer, or microprocessor. I am currently designing a VMEbus CPU card using the MC68000 and the NS32081, among other components. I am a Vax computer user. The Weitek information turned up as I was typing this message, so it is included, though very incomplete. Here are some timing specifications for register-to-register floating point instructions on a variety of computers and microprocessors. All specifications are for hardware-assisted floating point operations using the specified hardware floating point coprocessor. The Vax timings are for the standard DEC floating point accelerator hardware. These specificatons are taken from literature provided by the vendors. The Weitek chip set is supposed to be an MC68020 coprocessor implementation. However, it is not known whether the timings given here are actually register-to-register timings with the Weitek chip set interfaced as a coprocessor to an MC68020, or whether the timings are of operations internal to the Weitek chip set. The literature is not clear, mainly because it is taken from trade journal press releases. The Weitek chip set is so fast that I opted to included it here, even though I do not have data sheets for the parts as of yet. All other specifications are taken directly from the vendors' data sheets and other vendor technical documents. It is unclear for many scientific minicomputer users that the NS320xx/NS32081 and MC680xx/MC68881 combinations will be viable substitutes for the 11/750 and 11/780 Vaxes. The rumored announcement/arrival of the so-called MicroVax II which alleges to provide 11/780 performance (90% or better for floating point, up to 105% for other instructions) should also address the financial arguments by placing an 11/780 class (including floating point) computer into the microcomputer workstation market. The MC68020/WTL1164,WTL1165 combination looks very interesting. As of the date of this posting the MC68881 has only been distributed as samples in the 12.5 MHZ version. FADD = 32 bit single precision register-to-register floating point add. FSUB = 32 bit single precision register-to-register floating point substract. FMUL = 32 bit single precision register-to-register floating point multiply. FDIV = 32 bit single precision register-to-register floating point divide. DADD = 64 bit double precision register-to-register floating point add. DSUB = 64 bit double precision register-to-register floating point subtract. DMUL = 64 bit double precision register-to-register floating point multiply. DDIV = 64 bit double precision register-to-register floating point divide. ===================================== * * * ALL TIMINGS ARE IN MICROSECONDS * * * ===================================== Computer or Microprocessor FADD FSUB FMUL FDIV DADD DSUB DMUL DDIV ========================= ==== ==== ==== ==== ==== ==== ==== ==== 11/780 Vax w/FPA 1.19 1.19 1.19 4.60 2.39 2.59 3.40 8.82 11/750 Vax w/FPA 1.76 1.75 2.27 6.44 2.63 2.63 4.69 12.80 11/730 Vax w/FPA 4.81 7.85 9.88 11.56 9.85 13.27 23.07 23.34 MC68020/MC68881 16.67 MHZ 2.80 2.80 3.10 3.80 2.80 2.80 4.00 5.90 MC68020/MC68881 12.5 MHZ 3.73 3.73 4.13 5.07 3.73 3.73 5.33 7.87 NS32016/NS32081 10 MHZ 7.40 7.40 4.80 8.90 7.40 7.40 6.20 11.90 NS32016/NS32081 8 MHZ 9.25 9.25 6.00 11.13 9.25 9.25 7.75 14.86 Weitek WTL1164,WTL1165 - - 0.360 - - - 0.600 - The Weitek line is very bare. The fact that an MC68020 floating point coprocessor is being manufactured by Weitek is interesting, and it at least promises to be very fast. Perhaps someone else can look into the Weitek situation. The trade journal "new product" information was pretty flaky. Steven M. Ward Center for Astrophysics 60 Garden Street Cambridge, MA 02138 (617) 495-7466 {genrad, allegra, ihnp4, harvard}!wjh12!cfa!ward