486sx and 486dx

Discussion about old PC hardware.

Re: 486sx and 486dx

Postby derSammler » 2018-2-02 @ 10:19

Yes, that would make sense. But then the jumper selects which CPU to use, and not really if an FPU is present. :)
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Re: 486sx and 486dx

Postby Scali » 2018-2-02 @ 10:21

derSammler wrote:Yes, that would make sense. But then the jumper selects which CPU to use, and not really if an FPU is present. :)


Well, I think that's a given... The FPU is internal, so only the 486 chip used determines whether the FPU is present or not :)
I don't think it's possible to disable the FPU in a 486DX externally.
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Re: 486sx and 486dx

Postby CkRtech » 2018-2-02 @ 10:26

Different jumper configurations for SX vs DX on a 486 is pretty normal stuff. I just assumed it was chipset related.
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Re: 486sx and 486dx

Postby RobertJ » 2018-2-02 @ 12:55

Scali wrote:
badmojo wrote:Never heard if any game taking advantage of it, could you provide an example?


Falcon 3.0 had an enhanced mode if you had an FPU.


That's the one I was specifically thinking about. It was one of my favorite flight sims of that era, and the reason I upgraded to a DX at the time.
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Re: 486sx and 486dx

Postby Baoran » 2018-2-02 @ 13:41

This is almost same as the motherboard I have: http://stason.org/TULARC/pc/motherboard ... 0037S.html

One of the differences is that one of the jumpers that is suppose to tell the cpu type to the motherboard is missing.

20180202_153440.jpg


As you can see where the JP27 is suppose to be, there is no jumper.
Another difference is that there is winbond chip where it says "real time clock" in the picture and there is a barrel battery next to the keyboard connector.
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Re: 486sx and 486dx

Postby vladstamate » 2018-2-02 @ 14:00

Another software I used a lot that required FPU was VistaPro. I still have that installed on all my retro PCs starting from 386 to Pentium III. Very fun software to play with.
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Re: 486sx and 486dx

Postby Baoran » 2018-2-04 @ 09:20

Quake benchmark works 3.8 fps no matter how I set the jumpers, so no idea what the jumpers actually do.
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Re: 486sx and 486dx

Postby Scali » 2018-2-04 @ 12:09

Baoran wrote:Quake benchmark works 3.8 fps no matter how I set the jumpers, so no idea what the jumpers actually do.


Perhaps it's just to set the correct CPU model at the BIOS POST screen?
Does it change from SX to DX?
Perhaps you could also try running some CPU info software from Norton or such, which try to determine the CPU type independently, and see if they change based on the jumpers?
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