Because the H and V ports are used to pass a signal that synchronizes the video signals so that the picture does not roll vertically V and tear horizontally H. The signals that do the syncing and that are passed through these H and V ports can be of two different types - either TTL sync signals or non-TTL Extron CrossPoint 300 124 Matrix Switcher to Transistor Logic, a communications protocol technology developed by Texas Instruments years ago, typically used[…]
