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how to tell if onboard video is running on ISA or local bus?


Veteran Member
Aug 28, 2010
Scottsdale, AZ
how do you tell in a 486 PC if your onboard video is running on an ISA or VLB bus? does all onboard video on 486 class machine automatically use a local bus? The PC in question is my Tandy 425 SX PC. It uses a riser card with 3 ISA slots and has a built in Western Digital WD90c31A-LR chip. The documentation I read didn't mention local bus. I used to have a Packard bell that was very similar to this machine and had 3 ISA slots but the built in headland chip was usually faster then any added ISA cards because it was running on a local bus.

other then doing benchmark tests is there a well to tell what bus a built in video chip is using?


Veteran Member
Jan 21, 2011
Some digging reveals the WD chip set was originally ISA based. There were some VL Bus cards with the chip, but were poor performers since the chip only has a 16-bit data bus. On board local bus video and IDE didn't become commonplace until 1993.