sliderider wrote:From Wikipedia […]
Show full quote
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" 😉 )