Would there be a problem using VL-Bus cards with a POD? I read that VL-Bus is 486 dependent but since the POD is adapted to utilize the 486 motherboard architecture, would it still cause problems?
Also, how about with the Nexgen nx586? Would that be a problem? I only ask because I don't have any VL-Bus cards right now to test.
I've used a POD in a VL-bus motherboard with VLB graphics card and IDE/IO controller, and didn't notice any issues.
I did have one motherboard that didn't like the POD, but it didn't like any CPU with over 8kb of L1 cache... it would hang on boot with an Intel DX4 or POD installed, even a Kingston Turbochip (5x86 133 with builtin voltage regulator) wouldn't work... but an AMD DX4 with only 8KB of cache works fine.
If you are squeamish, don't prod the beach rubble.
I don't see any reason why one would even consider the possibility of a Pentium somehow not being compatible with VLB cards when many VLB boards came with the bigger white CPU socket which was specifically made for the POD. Heck, there were even some Pentium VLB motherboards made.
I've never read anything suggesting VLB being somehow "486 dependent".
And afaik there was only 1 manufacturer for nx586. Why in the world would they design a board with VLB slots when their own processor would somehow not support it???
wrote:I don't see any reason why one would even consider the possibility of a Pentium somehow not being compatible with VLB cards when many VLB boards came with the bigger white CPU socket which was specifically made for the POD. Heck, there were even some Pentium VLB motherboards made.
I've never read anything suggesting VLB being somehow "486 dependent".And afaik there was only 1 manufacturer for nx586. Why in the world would they design a board with VLB slots when their own processor would somehow not support it???
From Wikipedia
"The VESA Local Bus was designed as a stopgap solution to the problem of the ISA bus's limited bandwidth. VLB had several flaws that served to limit its useful life substantially:
80486 dependence. The VESA Local Bus relied heavily on the Intel 80486 CPU's memory bus design. When the P5 Pentium processor started to gain mass acceptance, circa 1995, there were major differences in its bus design, and the VESA Local Bus was not easily adaptable. This also made moving the bus to non-x86 architectures nearly impossible. Few Pentium motherboards with VLB slots were ever made."
nx586 might be a problem because the memory architecture is completely different from 486 motherboards or even Pentium motherboards. Just because someone manufactures a motherboard with a particular slot on it does not mean that it is going to work flawlessly.
wrote:From Wikipedia […]
From Wikipedia
"The VESA Local Bus was designed as a stopgap solution to the problem of the ISA bus's limited bandwidth. VLB had several flaws that served to limit its useful life substantially:
80486 dependence. The VESA Local Bus relied heavily on the Intel 80486 CPU's memory bus design. When the P5 Pentium processor started to gain mass acceptance, circa 1995, there were major differences in its bus design, and the VESA Local Bus was not easily adaptable. This also made moving the bus to non-x86 architectures nearly impossible. Few Pentium motherboards with VLB slots were ever made."
nx586 might be a problem because the memory architecture is completely different from 486 motherboards or even Pentium motherboards. Just because someone manufactures a motherboard with a particular slot on it does not mean that it is going to work flawlessly.
I've read the wiki and it states what you quote, but not why.
After a bit of searching I came a cross a couple pages with an answer to this question, of which I found this one to be the one with the best explanation.
Apparently VLB uses a 32 bit memory bus and as Pentium uses 64 bit, this presented a problem. As Socket 3 POD also uses a 32 bit bus, this particular little piece of data seems like a non-issue to me.
Apparently VLB wants a 32 bit x86 bus.
Anyone else with a bit more knowledge have any other ideas? I'm basically putting, that what I posted above, together quickly.
And manufacturers have manufactured a lot of things that will simply not work 100% correctly. Sometimes they are even asking for trouble...but oh well, doing a bit of housework can save any retro guy a lot of pain afterwards 😉
Edit:Now that I'm thinking more about it, I would say that the answer to your question would be something like: VLB in itself shouldn't cause problems with non-486 CPU's. The problem seems to lie with the way the VLB was implemented in non-486 boards. Hope this provides a good enough answer to you 😉
(and feel free to say "thank you" 😉 )
Pentium Overdrive for Socket 3 is a Pentium redesigned for full compatibility with the 486 platform. That's all there is to it. Yes VLB works.
