Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!ira.uka.de!fauern!faui43.informatik.uni-erlangen.de!csbrod From: csbrod@immd4.informatik.uni-erlangen.de (Claus Brod) Newsgroups: comp.sys.atari.st.tech Subject: Re: Mega STe Questions Message-ID: <1991Jun21.105541.25018@informatik.uni-erlangen.de> Date: 21 Jun 91 10:55:41 GMT References: <1991Jun19.114741.11944@informatik.uni-erlangen.de> <1991Jun20.122304.23243@ugle.unit.no> Distribution: comp Organization: CSD., University of Erlangen, Germany Lines: 30 stigvi@Lise.Unit.NO (Stig Vidar Hovland) writes: >In article <1991Jun19.114741.11944@informatik.uni-erlangen.de>, csbrod@immd4.informatik.uni-erlangen.de (Claus Brod) writes: >|> >|> The 68881 is optional. The Mega STE's FPU is programmed just like >|> the FPUs available for the standard Mega, so there should be some >|> development packages supporting it. >|> >How is it programmed on a standard Mega? Will programs written for the TT and 68882 run correctly on a Mega STE and 68881? The FPUs available for 68000 computers are programmed via registers in memory. I don't know the base address of the FPU in a Mega, but what you do is basically write the appropiate values into a register using move instructions, then write the instruction into a instruction register, and fetch the result from a result register. This is due to the fact that the 68000 has no proper coprocessor interface like the 68020 or 68030 have. Programs that use TT FPU will use Line F instructions that won't work on a 68000. You may, however, write a Line F emulator for the standard 68000 to emulate a FPU coprocessor in the system. ---------------------------------------------------------------------- Claus Brod, Am Felsenkeller 2, Things. Take. Time. D-8772 Marktheidenfeld, Germany (Piet Hein) csbrod@medusa.informatik.uni-erlangen.de Claus_Brod@wue.maus.de ----------------------------------------------------------------------