apm233m@vaxc.cc.monash.edu.au writes:

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>> ....   When you
>> are asking the AMD chip to do a FPU instruction you can get delays of up
>> to _5_ milliseconds before the chip returns an error so that the Software
>> FPU emulation can kick in. This [unfortunatly] means that AMD chips go at 
>> about the speed of a 8mhz XT .....
>> ........
>> ---
>> Disclaimer: My machine is a 386/33 - with an AMD chip w/o FPU. ....

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>I don't understand. Are you saying that this is a problem just with 40MHz
>parts or just with 33MHz parts... or both?

   I did make that a bit confusing, didn't I. :-\   Anyway it's on all the
AMD 386 series chips [as far as I know]

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>My machine has a 33MHZ AMD 386 cpu and an OPTI chipset. I have written an
>80387 emulator which works with djgpp and I have done quite a bit of work in
>trying to get reasonable speed. Whenever I have checked the details of timings,
>I find that I can account for most of the cycles taken to emulate any function.
>The user-program-level performance of my emulator is: less than 100 microsec
>for basic arithmetic, less than one millisec for any other function.

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>Maybe the timing problem you have found is due to the support chipset? Or
>perhaps the BIOS has not been told that an 80387 is not installed?

    I'm not a CPU guru, and I'm just relaying what I saw in the *hardware
groups a few months back.  As far as I recollect the CPU just halts for some
reason.

        Joe