DECpc 420SX Video Question

[naturepatch]

Hi - I purchased an old DEC PC 420sx system to game in DOS. The onboard video chip is not very powerful. I purchased an old ISA VGA card and when I install it, all video is lost. Is there a way disable onboard video so that the add on card will provide the video? I don't see jumpers and have no motherboard manual / owners manual. Thanks in advance...

 

[Lou - N2MIY]

I have a DEC PC756 that I use for checking out MFM hard disks. It too has on-board VGA and has two jumpers on the motherboard for enabling/disabling the on-board VGA. My PC756's motherboard was made by DEC, and so if yours was too, it might also have such jumpers - be sure to look again really carefully.

Lou