The biggest hack in the known universe. Some idiots back in 1992 or so noticed that the ISA bus was too slow, so they decided to extend the 486 processor bus so that cards could interface with it. Unfortunately, it was unstable, you couldn't put more than 2 or 3 cards in, it didn't work at all over 33Mhz, and since it was tied so closely to the 486 bus, it didn't scale well to newer processors. It was replaced by the PCI bus thankfully.

Strange - I bought a 486DX50 system in 1995 with VLB graphics and IDE cards. Ran at system bus speed of 50MHz, with no clock multiplying. That's above 33MHz!

I upgraded the motherboard and CPU after two years of problem-free computing to an AMD 486DX4-120 running at 3x the 40MHz VESA bus speed, with the same two cards. That's still above 33MHz.

That system is still my only PC and dual-boots Linux 2.4 and Win95, both of which run without problems. That's not "not working at all".

I still wish I'd bought PCI, though. It was not quite mature enough when I had to make the decision...