Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uwm.edu!cs.utexas.edu!oakhill!eric
From: eric@oakhill.UUCP (Eric Quintana)
Newsgroups: comp.sys.m68k
Subject: Re: 68882 with slower 68020?
Message-ID: <3513@rorschach.oakhill.UUCP>
Date: 10 Jul 90 22:16:30 GMT
References: <16340003@hpfinote.HP.COM>
Reply-To: eric@rorschach.UUCP (Eric Quintana)
Organization: Motorola Inc., Austin, Texas
Lines: 20

In article <16340003@hpfinote.HP.COM> den@hpfinote.HP.COM (Don Novy) writes:
>
>  Are there any limitations to using a 68020 with a faster 68882? I have read
>the manuals and they state that the 68020 clock cannot be more than 1.5X the
>68882 clock, but can you run the 68020 slower than the 68882?

The 68882 can handle a main CPU that is clocked 1.5X the FPU clock or less.
There is no lower bound.

>  Specifically I have been using a 33.3 MHz 68882 with a 25 MHz 68020 for
>quite a while with no problems. What will happen if I try a 50 MHz 68882 with
>a 25 MHz 68020?

This should work fine.  If you have violated the clock ratio, you should
notice spurious protocol violations.

>Don Novy
>den@hpfitst2.hp.com

Eric Quintana               ...!cs.utexas.edu!oakhill!eric