Date: Wed, 25 Aug 1999 15:58:46 -0600 From: Wes Peters <wes@softweyr.com> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Sv: K6/3 on 3.2-STABLE - PROBLEM SOLVED Message-ID: <37C46716.633BE9B2@softweyr.com> References: <19990824132943.B11107@proxydev.inktomi.com> <199908242133.OAA18621@apollo.backplane.com> <19990824154432.A21013@proxydev.inktomi.com> <19990825020108.B20512@forty-two.egroups.net> <007c01beef22$859036a0$0e00a8c0@neland.dk> <199908251820.LAA14122@apollo.backplane.com>
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Matthew Dillon wrote:
>
> :
> :Back around 1980, I overclocked my 5MHz z80 to 6MHz. It worked without problems, except that for-next loops in comal didn't exit as expected. That was also reproducible...
> :
> :Leif
>
> In the early 90's I regularly ran 10 MHz 68000's at 20 MHz (which was
> about the limit the dynamic ram at the time could handle).
>
> When motorola started phasing out the DIP version of the 68000 after
> many years of good service, one of their big customers noted that Motorola
> had updated the process many times but had never updated the timing specs
> during virtually the entire life of the product, and wanted to know how
> fast the chip could actually be run.
>
> So Motorola tested it. I believe the 12.5 MHz spec'd chip tested
> to 80 MHz. Not bad!
I used to work on an embedded system that used the 16 Mhz 68EC000, and we
encountered a situation where we needed to raise the clock to 20Mhz. We
substituted a couple of 40 Mhz crystals for the 32 Mhz crystals and it worked
fine. The next three boards we tried didn't work at all.
We called Motorola and asked about 20 Mhz parts. They were on the verge of
releasing them, so we asked for samples. They shipped us 20 parts directly
out of factory test in south-east asia. The only difference between the 16
and 20 Mhz parts were the worst-case timing.
--
"Where am I, and what am I doing in this handbasket?"
Wes Peters Softweyr LLC
http://softweyr.com/ wes@softweyr.com
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