hamilton@intersil.uucp (Fred Hamilton) (11/02/89)
So I finally got my LUCAS/FRANCES purring away last night, running something like 1.42 times an A2620 according to the "Speed" benchmark, and I start trying out things. I logged onto a local BBS, downloaded the latest version of SetCPU (V15, 1.5, or 0.15) run it and it says: "FPU Logic Error" It almost burst my happly little bubble. The docs say something about an error where the FPU and MMU share the same bus, but I don't have an MMU. What does this mean? Is this anything I should worry about? Anyway, I am amazed at how beautifully my old 1000 is running-I've fallen in love with my Amy all over again :-)! Thanks Brad! -- Fred Hamilton Any views, comments, or ideas expressed here Harris Semiconductor are entirely my own. Even good ones. Santa Clara, CA
daveh@cbmvax.UUCP (Dave Haynie) (11/04/89)
in article <174@intersil.uucp>, hamilton@intersil.uucp (Fred Hamilton) says: > So I finally got my LUCAS/FRANCES purring away last night [..] [run] > SetCPU (V15, 1.5, or 0.15) and it says: > "FPU Logic Error" > What does this mean? Is this anything I should worry about? What this means is that the FPU address isn't fully decoded. The 68020 accepts 8 coprocessors, each of which sits at a particular address in CPU space. If the coprocessor address isn't fully decoded in hardware, you'll see that coprocessor aliased at one or more valid coprocessor addresses. In practice, most systems only use two coprocessors; the FPU and the MMU. What SetCPU is telling you here is that the FPU in your system is responding to an MMU coprocessor address. While this state can be detected without causing any real problem if you're looking for this situation, there's no guarantee that any future MMU client (like some future OS) will check for incorrectly decoded FPUs when it's looking for the MMU. So this isn't a big deal today, but could be a problem in the future. > Fred Hamilton Any views, comments, or ideas expressed here -- Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy Too much of everything is just enough