386 Video Boot Issue

[cr1901]

Old VGA cards often test the connector to determine if a display is colour or monochrome, when using a newer VGA monitor it often gets confused and results vary.
I only have a couple of Trident cards which do this - so I make sure to use these with old CRTs - otherwise I try and use a different card that doesn't do it.

Hmmm... how can video cards tell the difference? Was there something in the original VGA standard/original VGA signaling that made this possible?