SiS 486 Chipset Datasheets

Discussion about old PC hardware.

SiS 486 Chipset Datasheets

Postby NJRoadfan » 2013-6-18 @ 00:11

I am attaching these here in PDF for convenience. SiS used to host these documents on their site, but they are long gone now. Unfortunately they only posted the 85c471 VLB and 85c496/497 PCI datasheets and none of the earlier ones like the ISA 85c401/402 or EISA 85c406/411. Either way, these datasheets are handy for deciphering the advanced chipset configuration options found in many BIOS, most of which is applicable to the older chipsets as well.

If anyone wants the later Pentium chipset datasheets, those are available as well.
Attachments
SiS 496-497.pdf
SiS 85c496/497 Datasheet
(1.38 MiB) Downloaded 715 times
SiS 471.pdf
SiS 85c471 Datasheet
(945.7 KiB) Downloaded 515 times
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Re: SiS 486 Chipset Datasheets

Postby noshutdown » 2013-6-18 @ 10:52

"Both CPU and PCI clock are supplied clock by external clock generator. CPU clock may varies from 50 MHz to 2 MHz. When the CPU clock frequency is lower than or equal to 33MHz, the PCI clock frequency is equal to CPU and when the CPU clock frequency is higher than 33 MHz., the PCI clock frequency is half of CPU clock."
-page41
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Re: SiS 486 Chipset Datasheets

Postby Anonymous Coward » 2013-6-18 @ 11:15

I read that too....but I think we are reading too much into it. I think it just means that the PCI clock *should* be half CPU clock....not that this process will happen automatically. Since an external clock generator is used, doesn't that kind of imply that it is not a feature of the chipset? All known SiS PCI board with dividers are set that way manually with a jumper.
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Re: SiS 486 Chipset Datasheets

Postby feipoa » 2013-6-19 @ 02:30

As I probably already pointed out to Anonymous Coward via PM, I saw no evidence that the SiS chipset has any control over the PCI divider clock. When I ran two different SiS boards at 40 and 50 MHz, I measured the PCI clock freq. with an oscilloscope, however the PCI frequency was not halved. The only way the PCI frequency gets halved is when a jumper near the clock generator chip was switched. Some SiS motherboards don't explicitely say which jumper is the PCI half frequency jumper, but you can figure it out by looking at the jumper configuration for the 50 MHz setting.

Edit: The SiS 496/497 manual also mentions that the Cyrix 5x86 linear burst mode is supported, however the two SiS boards I tested would hang up when linear burst was enabled.

Perhaps this SiS preliminary was in need of revision?
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Re: SiS 486 Chipset Datasheets

Postby NJRoadfan » 2013-6-19 @ 04:42

That was the "latest" version in 1998, so there likely isn't anything newer.
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Re: SiS 486 Chipset Datasheets

Postby JaNoZ » 2013-6-19 @ 05:50

How can anyone tell which chip is capable of edo or not??
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Re: SiS 486 Chipset Datasheets

Postby feipoa » 2013-6-19 @ 07:09

Are any SiS 496/497 boards capable of EDO? The 3 differen't boards I tested were not.
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Re: SiS 486 Chipset Datasheets

Postby Stiletto » 2013-7-09 @ 18:31

If anyone wants the later Pentium chipset datasheets, those are available as well.


May as well upload those...
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