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FOR SALE: 486 Motherboaed QDI US491P3 intel i486 sx

Chuck(G) said:
But faster than traditional ISA cards, right?

I don't understand what the problem is then.... :huh: I must be very dense today.
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The VESA Local Bus relied heavily on the 80486"s memory bus design as the 386 memory bus lacked the speed and output.
VLB was heavily dependant on a Math Co-Processor which most 386 Motherboards did not include. There was a seperate socket in which you could add one at a leter time. SX and DX with a 386 was different than with a 486. A 386SX was a 16bit Motherboard where a 486SX meant that it had no Math Co-Processor. The 386DX was a 32bit Motherboard but still lacked the Math Co-Processor where a 486DX included the Co-Processor. Vesa Local Bus relied on the 32bit bus, the math co-processor and the faster RAM of a 486.

VLB is faster than ISA but was very limited in a 386 configuration due to all of the limitations of the Motherboard, Math-CO, RAM and etc. and acted more like a regular ISA card than a VLB card. VLB will also have some limitations in a 486SX Motherboard due to no Math-CO but will be significantly faster than in a 386 MB.

I have a 486 VLB motherboard with a 486-DX2-50MHz CPU (if I remember correctly) that was in a working computer many years ago. I would value it at around $20 plus shipping. The only reason that I do not currently use it is because I upgraded to a 486 PCI motherboard as I had a lot of PCI cards that worked better with my old games from the 80's and 90's even though PCI did not come out until 1993.
 
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VLB & MathCo

VLB & MathCo

cudasales said...VLB was heavily dependant on a Math Co-Processor
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How so ?
It worked just fine with 486 SX systems. There's nothing in the VLB spec that requires a numeric coprocessor, at least from what I remember. There isn't any signaling on the bus that indicates if the numeric coprocessor is present or not.

patscc
 
kb2syd said:
There exists entire stores on EBay with inventories of old equipment. It is my opinion that they list everything they can with a very high price on the chance that someone somewhere needs that exact board for replacement in an existing commercial system. If I had that board in a live server that could not be replaced, $150 is not too much. I don't and I suspect not many do.
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That's the premise that my website works on.

The percentage of NON-company sales I get on my site is so vanishingly low that I can no longer cater to the segment whose first question is "how much".

A lot of the stuff gets sold after it's tested and before it gets up on the site now since I've trained people to ASK if they don't see it.

I must be doing something right because I'm getting new clients that were referred by current clients. Must be a "legacy grapevine" out there.
 
As stated VLB relied on the 486 memory bus quite a bit. The reason you could only use 2 or maybe 3 VLB cards per system is those cards would take turns hogging the memory bus and inducing wait states to the CPU. Even with the cache found on all 486 VLB systems using 3 cards causes slowdowns. So when you run VLB on a pentium or 386 system the setup is not optimal and the cards pretty much just run as slightly faster ISA cards, and I would think CPU benchmarks would drop a bit. Might as well just stay with ISA.
 
It's hard to say how well VLB will run on a 386, because it is heavily dependent on the implementation. I am currently running a 386/486 hybrid board similar to the one you mentioned, though it uses the OPTi495SX rather than SLC chipset. This is the only 386 VLB board I have ever owned, simply because it is so difficult to get them (at a reasonable price). This one happened to be a freebie.

I used the ATi Mach64 VRAM card for testing. I am lucky to have this card for both VESA local bus and ISA. I tested the graphics under Windows 3.1 using WinTune 2.0 using accelerated graphics drivers. I did not run any tests in DOS to measure VGA performance.

The following CPUs were used:

-AMD 386 40MHz
-TI 486SXL 40MHz (386/486 hybrid chip with 8kb cache)
-IBM 486DLC2 66MHz (386/486 hybrid chip with 16kb cache)

While I don't have the exact numbers on hand, I can tell you that the ISA version of Mach64 will typically deliver around 2.5mpixels/sec running 800x600 @ 64k colour when the bus runs at 8MHz. I used this mode in all my tests...just because this is what I typically will use on a system with a 2mb card. When testing the VLB card on the AMD 386, the performance slowed to less than 2mpixels/sec. Yes, you read that correctly...the VLB Mach64 actually performed worse than the ISA Mach64 in this configuration. Switching to the TI 486SXL CPU gave similar results. I think the ISA and VLB tests might have been almost equal for this CPU. However, with the IBM 486DLC2 things changed for the better, and the VLB card outpaced the ISA card by quite a bit. I think in the range of 3 to 3.5mpixels/sec. I am not sure if this is because of the larger cache or the increased CPU power.

It's possible that you may get entirely different results by testing at different resolutions and colour depths on different types of hardware. I just stuck with the hardware I am familiar with (ATi products), but I came to the conclusion for this particular board (495SX) the performance of VLB is not very good on a 386, and sometimes worse than even ISA.
 
Anonymous Coward said:
This is the only 386 VLB board I have ever owned, simply because it is so difficult to get them (at a reasonable price). This one happened to be a freebie.

.
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Is this also true of 486 VLB boards ?

If so, I have to get my camera interface workng once more. I have about 10 VLB AMD CPU 486DX50 motherboards and an almost equal number of VLB I/O and Video cards. Once I get things straightened out I'll put them up on this secton of the forum if they are desireable.

Guess I have to check EPay to get an idea of demand.

Lawrence
 
Micom 2000 said:
Is this also true of 486 VLB boards ?

If so, I have to get my camera interface workng once more. I have about 10 VLB AMD CPU 486DX50 motherboards and an almost equal number of VLB I/O and Video cards. Once I get things straightened out I'll put them up on this secton of the forum if they are desireable.

Guess I have to check EPay to get an idea of demand.

Lawrence
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Doesn't seem to be ANY demand for the 486 VLB boards around here. I doubt the situation is any different on ebay.
 
Unknown_K said:
As stated VLB relied on the 486 memory bus quite a bit. The reason you could only use 2 or maybe 3 VLB cards per system is those cards would take turns hogging the memory bus and inducing wait states to the CPU. Even with the cache found on all 486 VLB systems using 3 cards causes slowdowns. So when you run VLB on a pentium or 386 system the setup is not optimal and the cards pretty much just run as slightly faster ISA cards, and I would think CPU benchmarks would drop a bit. Might as well just stay with ISA.
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Actually if memory serves, it has little to do with wait state and everything to do with loading on the bus; the 486 can't drive too many devices without buffering.
 
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