VOGONS


First post, by retro games 100

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I've been doing some testing recently, with an overclocked P75 chip, running at a bus speed of 50 MHz. Generally speaking, it doesn't work too well. Yes it does work on one board well, but on most other boards I have tried, you get issues. I want to get an Intel DX-50, the CPU without a multiplier. This will allow me to test 486 mobos with a 50 MHz bus, without the CPU getting too stressed. In fact, it won't be overclocked at all!

I had a look on cpu-world com here, and noticed that these versions exist: SX408, SX409, SX518, SX546, SX547, SX705, SX710. Does anyone know which is the best version to get? Thanks a lot for any advice.

Reply 1 of 15, by luckybob

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the board matters more than the chip does. At least at that bus speed. I have a DX-50 with a GOOD high quality motherboard. The chip wont work in other boards well so I've kept them together as a set. Sadly there is no vlb on this combo but i cant have everything.

I'm debating putting all my spare parts on ebay here in the next few days.

It is a mistake to think you can solve any major problems just with potatoes.

Reply 2 of 15, by Anonymous Coward

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If I were you, I would get the latest stepping possible. Intel initially had problems with the DX-50 overheating and switched to a smaller manufacturing process. You can usually tell what's what by looking at the size of the gold die cover on the bottom of the chip.

I can't say I recommend 50MHz unless you go the EISA route, or use a PCI board with a divider. VLB is doable, but you're going to have to choose whether to put EIDE or VGA on the VLB. Getting one card going at 50MHz is hard enough. Two is asking for a miracle.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 3 of 15, by retro games 100

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Hehe, I like the way you describe things! 😀 I'm confident that I will able to test a DX-50 by early next week. BTW, I've got a 16-bit ISA EIDE controller. I reckon it's OK. I'll just keep one VLB slot occupied for the VGA. Thanks for the info, people. BTW, I like luckybob's signature.

Reply 4 of 15, by Tetrium

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Anonymous Coward wrote:

You can usually tell what's what by looking at the size of the gold die cover on the bottom of the chip.

Ok, so if I look at the size of the gold die cover...what am I supposed to be looking for? The smaller ones are the newer, or the older ones?

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Reply 5 of 15, by Anonymous Coward

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The ones with the smaller plates should be made on the newer process.

I'm having a difficult time finding the documentation to back up my claims. But as I understand it, initially the DX-50 used the same 1 micron process as the rest of the original 486DX/SX CPUs. On these chips the gold cap on the bottom covers the entire area not covered by pins.

I am quite certain that at some point (don't know the exact time), due to heat related issues intel switched the DX-50 over to the smaller 0.8 micron process used by the DX/2 CPUs.

Look up 486DX on this sheet, and you can see 1 micron, 0.8 micron listed there.

http://www.intel.com/pressroom/kits/quickreffam.htm#i486

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 6 of 15, by Anonymous Coward

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http://www.cbronline.com/news/intel_finds_bug … or_a_week_or_so

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 7 of 15, by retro games 100

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Anonymous Coward wrote:

If I were you, I would get the latest stepping possible. Intel initially had problems with the DX-50 overheating and switched to a smaller manufacturing process. You can usually tell what's what by looking at the size of the gold die cover on the bottom of the chip.

I can't say I recommend 50MHz unless you go the EISA route, or use a PCI board with a divider. VLB is doable, but you're going to have to choose whether to put EIDE or VGA on the VLB. Getting one card going at 50MHz is hard enough. Two is asking for a miracle.

Have I just been very lucky, because in my post here, I have managed to get two VLB cards (VGA and IO) working @ 50 MHz, using a DX-50 MHz CPU. This post describes a VLB 486 SiS chipset-based mobo, manufactured by FreeTech.

Reply 10 of 15, by sliderider

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retro games 100 wrote:
sliderider wrote:

Be sure you try it at 60/60 and 66/66.

Completely impossible! 😀

It's only impossible until someone does it. 😜

You may get a golden chip that can take being overclocked.

Besides 60mhz is only a 20% OC and 66 is only 22%. A good fansink would probably make it possible.

Reply 11 of 15, by retro games 100

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To overclock an Intel DX-50 CPU to 60MHz or 66MHz requires the mobo's bus speed to be increased from 50MHz to 60MHz or 66MHz. The SiS chipset does not support these bus speeds, so it's impossible!

Reply 12 of 15, by DonutKing

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I have this board and it supposedly supports 66, 80 and 100 MHz bus speeds, although I haven't tried them. It does run at 4Mhz though 😀 (no boot at 2MHz)

http://stason.org/TULARC/pc/motherboards/F/FI … 486-GIO-VT.html

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Reply 13 of 15, by Tetrium

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retro games 100 wrote:
sliderider wrote:

Be sure you try it at 60/60 and 66/66.

Completely impossible! 😀

Well, my AMD DX-40 did manage to boot at 60Mhz and 66 Mhz, so the newer DX-50 might be perfectly capable of that.
Btw, some Intel DX4's have a 2x multi also (making it a DX2-100 😉 ). The ones which have the 2x multi are listed on the wiki

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Reply 14 of 15, by retro games 100

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Just to clear a few things up! 😀

* When I said that a bus speed of 60 or 66 could not be achieved, I was referring to the FreeTech SiS chipset-based 486 mobo. However, it actually makes no difference, because I'm fairly sure that this also applies to the 486-GIO-VT mobo as well. In fact, the only 486s that have an undocumented bus speed of greater than 50 appear to be late era PCI UMC chipset-based mobos.

* The speed jumper settings of 60 and greater for the 486-GIO-VT on that Stason webpage are for internal speeds. For example, a DX4-100 has an internal speed of 100, requiring an external speed of 33. External speeds are the bus speeds, and they can only go up to 50 on most 486s. You'll sometimes see the internal speeds listed on Stason as i50, for example. Sure, it does list 4MHz in that table, and that would be for the bus.

* "Well, my AMD DX-40 did manage to boot at 60Mhz and 66 Mhz, so the newer DX-50 might be perfectly capable of that." I bet the board you tried that DX-40 on was a PCI 486 UMC chipset-based mobo. Yes, the DX-50 might be perfectly capable of that, but not in a SiS chipset based 486 mobo, because it doesn't support the necessary bus speed.

* Returning to the topic of the 486-GIO-VT mobo, and the idea that it might support 100 bus speed. What 486 CPU listed at the top of that Stason webpage would POST at such a speed? I can't think of one. In fact, I can't think of any 486 CPU that would work at that speed.

Reply 15 of 15, by Tetrium

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Ah, I see where you're coming from RG100 😉
It's the board that's the bottleneck, not the CPU 😉

Btw, TH99 is completely lacking when it comes to undocumented 486 FSB jumpers and RG100 is right about TH99 mentioning the internal speed.

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