Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!usc!ucla-cs!oahu.cs.ucla.edu!stephen From: stephen@oahu.cs.ucla.edu (Steve Whitney) Newsgroups: comp.sys.atari.st Subject: Re: Atari TT 030 Launched! Keywords: Atari TT Message-ID: <36147@shemp.CS.UCLA.EDU> Date: 11 Jun 90 18:27:08 GMT References: <81214@tut.cis.ohio-state.edu> <1990Jun6.044350.20403@cbnewsh.att.com> <5503@jhunix.HCF.JHU.EDU> Sender: news@CS.UCLA.EDU Distribution: usa Organization: UCLA Computer Science Department Lines: 34 In article <5503@jhunix.HCF.JHU.EDU> jheddy@jhunix.UUCP (Jared Brennan) writes: > > The 33% speed increase in Atari ST programs run on the TT has aroused >quite a bit of interest on the net recently, because this is rather minimal >compared to the speed increase expected given 2X clock rate, 2X data bus size, >caching, etc. However, I believe that the line A traps are real instructions >on the 68030, while they are invalid on the 68000, which allows them to be >used for ST graphics primitives. So, contrarily enough, the line A traps >are "illegal" instructions on the 68030 TT, while they work fine on the >68000 ST. The result being that you have to go through some gymnastics to >run ST programs on the TT. Hence, the limited speed increase. I just flipped through the 68030 manual to check this. The verdict is: The Line-F emulator is now used as teh floating point coprocessor interface in the 68030 (and to call the inetrnmal FPU on the 68040), but the line-A emulator is still there. Until TOS 1.6, TOS used the line-F emulator internally for dispatching system calls memory efficiently. That particular interface was never made public because it was known that the line-F emulator was going to be the coprocessor interface in the 68020 and above. From what I hear from Atari on GEnie, the speedup of the TT is more like 5x on older programs, but I'm sure floppy I/O and such don't count there. You should see some semi-official numbers soon. >-- >. . . Yet another shallow and badly thought-out opinion from: >Jared Brennan BITNET: JHEDDY@JHUNIX,JHUVMS -- Steve Whitney "It's never _really_ the last minute" (())_-_(()) UCLA Comp. Sci. Grad. Student | (* *) | Internet: stephen@cs.ucla.edu UCLA Bruin--> { \_@_/ } GEnie: S.WHITNEY `-----'