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From: robs@hpuamsa.neth.hp.com (Rob Slotemaker CRC)
Newsgroups: comp.sys.hp
Subject: Re: 68040 and Floats, is this true?
Message-ID: <28510052@hpuamsa.neth.hp.com>
Date: 11 Jun 91 07:27:43 GMT
References: <1991Jun07.213219.14174@lynx.CS.ORST.EDU>
Organization: HP-Sales Office-The Netherlands
Lines: 32

Some more information about the performance of systems with a 68040 processor :

  >  - Will his program perform better when using the 7.40 compiler ?
  Maybe.  If he is using a lot of float->integer conversions, yes it
  will really speed up.  If he is using sin/cos/tan, etc. don't expect
  anything from 7.40; you will have only a slight improvement.

  >  - Will his program perform better when using HP-UX 8.0 ?
  Yes.  All emulated instructions are no longer emitted (not completely
  true, but the one case where they are is extremely rare).  This is
  about as fast as code will get.

  >  - Is there a possibility to let the sin/cos functions NOT be emulated
  >    by using an external floating point processor ?  If yes, how should
  >    it be implemented ?
  This has not been considered, since the coprocessor interface which is on
  the 68030 and the 68882 is no longer present on the 040.  Thus, we would
  have to have a physical bus oriented chip, which could get messy.
  Besides, the emulated instructions ARE as fast as a 68882.  It's just
  that the 040 is not running at the clock speed of a 375.  When the 040
  gets up to 50 MHz, then this will become a non-issue.  For now, using
  direct calls instead of emulation gets you about the same performance
  as a 50 MHz 030.

  >  - Do you have any other suggestions to speed it up ?
  Move to 8.0 as quickly as possible. Of course this requires
  recompilation, but this is the best we can do.


Best regards,

Rob Slotemaker, Dutch CRC