Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!think.com!snorkelwacker.mit.edu!primerd!pbird14!danw From: danw@pbird14.prime.com (Dan Westerberg) Newsgroups: comp.arch Subject: Re: R4000 Message-ID: <1991Feb12.203337@pbird14.prime.com> Date: 13 Feb 91 01:33:37 GMT References: <45448@mips.mips.COM> Reply-To: danw@pbird14.prime.com (Dan Westerberg) Organization: Prime Computer Lines: 40 Nntp-Posting-Host: 129.122.50.34 In article , wolfe@vw.ece.cmu.edu (Andrew Wolfe) writes: |> |> |> Aha! |> |> As an purist I must insist that the R4000 is NOT Superpipelined. |> |> I believe the term is defined by Jouppi (IEEE TC Dec. 1989) - A superpipelined |> machine must have a multistage ALU. This defines the critical distinguishing |> characteristic of Superpipelined machines - Independence between sucessive ALU |> operations (Unless hardware stalls are used). |> |> The R4000 is an interesting heavily pipelined machine - but not ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ As a CPU development engineer here at Prime, and still a babe in the industry, I find all this controversy and talk about pipeline architectures rather interesting. I mean, so the R4000 uses an 8 stage pipe, so what? We at Prime have been building pipelines in our proprietary machines for YEARS! I grant you that our pipes have no where near the (predicted) performance of the R4000, but then again we don't have multiple foundries building silicon for us and we don't use full-custom design. Also, our architecture is *FAR* from RISC, more like super-CISC. I mean, c'mon, aren't pipelines old hat? What I find rather impressive is a 64-bit single-cycle integer ALU! Doing a full 64-bit operation in only 10ns (100MHz) in CMOS is one hell of a feat! dan -- =============================================================================== | | | Daniel I. Westerberg email: danw@tbird9.prime.com (or) | | Prime Computer Inc. danw@s49.prime.com | | MS 10-9 | | 500 Old Connecticut Path phone: 508-620-2800 x3644 | | Framingham, MA 10701 fax: 508-879-9098 | | | ===============================================================================