Path: utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!tut.cis.ohio-state.edu!iroquois.cis.ohio-state.edu!topping From: topping@iroquois.cis.ohio-state.edu (brian e topping) Newsgroups: comp.sys.mac.programmer Subject: Re: F Emulator, Just what the hey is it Message-ID: <82928@tut.cis.ohio-state.edu> Date: 12 Aug 90 20:37:51 GMT References: <1990Aug8.100755.1@mel.cipl.uiowa.edu> <19493@well.sf.ca.us> <82893@tut.cis.ohio-state.edu> <1990Aug10.184535.11051@caen.engin.umich.edu> Sender: news@tut.cis.ohio-state.edu Reply-To: brian e topping Organization: Ohio State University Computer and Information Science Lines: 46 In article <1990Aug10.184535.11051@caen.engin.umich.edu> billkatt@mondo.engin.umich.edu (billkatt) writes: >In article <82893@tut.cis.ohio-state.edu> brian e topping writes: >>In article <19493@well.sf.ca.us> oster@well.sf.ca.us (David Phillip Oster) writes: >>>68000 instructions that begin with the hex code 0xFxxx are reserved for >>>coporcessor chips. If you don't have a coprocessor, then you get a software >>>interrupt to an interrupt routine that is supposed to emulate the coprocessor. > >Says who? I don't recall reading and documentation on the 680x0's which says >you must or even should emulate a math coprocessor if you don't have one. >Clearly, it is a good idea, especially since more than one program will bomb >on Apple's new Macs with 68030's (020's?) and no math coprocessor, simply >because some programs assume 68030's and 68881/2's always go together. But >Apple didn't do anything WRONG by not emulating one. True, but it ALSO doesn't say anywhere that must or should include an A line emulator. Without this, the toolbox would be quite a different animal. I didn't say they did anything wrong, I am just wondering why they didn't make it a bear for people who really need the speed of the 881/2 and want to be compatible between machines. >SANE is more accurate than the 881/882. SANE uses 80-bit numbers instead of >96-bit numbers. SANE has routines for converting to/from ASCII strings, the >881 only does number crunching, how you get the numbers in and out are your >problem. SANE just wasn't meant as a replacement for the 881, it was >meant as a totally different method of approaching math processing. I tend to differ here also. It was indeed a replacement for the 881, as they are both IEEE 754 conformant methods of doing math. The fact that things are different between the two is a given considering different programmers worked on them under different constraints. 96/8 = 16, which is the same size of a 030 block move. Coincidence? I doubt it. I am not saying that accuracy is not important, but I doubt that IEEE would have specified a standard that was insufficient. (This may also show my unfamiliarity with how IEEE works.) There are a lot of routines the 881 does that SANE does not. Whatever the 881 does should have been emulated, the rest put into the _FP68K trap like they are now. Really, what is going on now is F line emulation (881 functions) through the A line emulator (A Traps and _FP68K). >Steve Bollinger ____/| Brian Topping