Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!uwvax!rang From: rang@cs.wisc.edu (Anton Rang) Newsgroups: comp.arch Subject: Re: ERISC??? Message-ID: Date: 21 Oct 89 03:08:59 GMT References: <1989Oct19.155752.13028@mentor.com> <126596@sun.Eng.Sun.COM> Sender: news@spool.cs.wisc.edu Distribution: usa Organization: UW-Madison CS department Lines: 20 In-reply-to: khb%chiba@Sun.COM's message of 20 Oct 89 16:55:05 GMT In article <126596@sun.Eng.Sun.COM> khb%chiba@Sun.COM (Keith Bierman - SPD Advanced Languages) writes: >>2. All instructions (operations) consume a single processor cycle with the >> possible exceptions of LOAD and STORE. > >I know of NO machine which performs single floating point OPS in 1 >cycle (some machines can achieve 1 fop/cycle when the pipes can be >kept full). Are there counterexamples, or is #2 simply at variance >with reality ? Lots of RISC systems implement floating-point using a coprocessor which runs asynchronously with the main (integer) processor. I think the idea here is not to let slow floating-point operations slow down the integer pipeline (but I could be wrong). Anton +----------------------------------+------------------+ | Anton Rang (grad student) | rang@cs.wisc.edu | | University of Wisconsin--Madison | | +----------------------------------+------------------+