Date: Fri, 7 Apr 1995 13:25:31 -0700 (PDT) From: John-Mark Gurney <gurney_j@efn.org> To: "Rodney W. Grimes" <rgrimes@gndrsh.aac.dev.com> Cc: terry@cs.weber.edu, matt@lkg.dec.com, vernick@cs.sunysb.edu, freebsd-hackers@FreeBSD.org Subject: Re: PCI/EISA/ISA performance Message-ID: <Pine.SUN.3.91.950407132117.7247A-100000@haus.efn.org> In-Reply-To: <199504060650.XAA02656@gndrsh.aac.dev.com>
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On Wed, 5 Apr 1995, Rodney W. Grimes wrote: > > > > On Tue, 4 Apr 1995, Rodney W. Grimes wrote: > > > > [...] > > > > > ISA does not have a specified clock frequency, I have seen it running > > > as fast as 16Mhz. Most boards die above 10Mhz, but some of the more > > > specialized industrial applications boards are spec'd upto 12 or 16Mhz. > > > > actually... I think that I am currently running my isa bus at 16mhz... I > > think for a while I was tring to run the bus at 20... but it was falling > > over and wouldn't boot... and this is with ne2000 clone cards... and > > other generic cards... > > I suspect you are off by a factor of 2, I haven't seen a ``generic'' > card of any sort that would run at 12Mhz, let alone 16Mhz. IDE controllers > are famous for falling over above 10Mhz (ever done a transmission line > simulation of an unterminated ribbon cable :-)). also... I am running a VL/Bus IDE controler if that makes any difference... > If your basing this on a CPUCLK/N value and you think CPUCLK is 66 Mhz > because that is what the crystal is you have made a mistake. Can you > tell me what CPU chip you have, what speed is it, and what your BIOS > says about ISA bus clock speed settings (list all the valid values). ok... I have a Intel 486/33DX that I am running at 40Mhz with a cpu cooling fan attached... I know that it is running at 40Mhz as I set the jumpers (mb used os chip) and sysinfo returns it... I have the CLK set to CLK2/2.... > Also what BIOS is it? AMI, Pheonix, AWARD or someone else. it is an AMI bios... > Realize a 486DX33, 486DX2/66 and 486DX4/100** all run with a CPUCLK of > 33 Mhz. A 486DX25, 486DX2/50 and 486DX4/75 all run with a CPUCLK of > 25 Mhz. A 486DX50 runs with a CPUCLK of 50Mhz. yup... so my computer is running at 40mhz... no double or anything... > ** The 486DX4/100 can also be run with a CPUCLK of 50Mhz if the motherboard > supports the 1:2 bus/core ratio jumper. kool... might want to look into this :) > Pentium processors are similiar except the CPUCLK values are 50Mhz, 60Mhz > and 66Mhz. possibly 90Mhz?? or is that achived some other way? thanks for the info though... TTYL... John-Mark Gurney gurney_j@efn.org -or- gurney_j@4j.lane.edu -or- Fido: John-Mark Gurney @ 1:152/56.2
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