Thanks to those who gave advice on hooking the BNC connector from HP 4951B serial protocol analyzer to an external monitor. I bought an adapter from Radio Shack Phono-to-BNC Adapter 278-254 and ran a regular phono cable from it to a Magnavox "Computer Monitor 80" green screen monitor. Works great, and now I can make out the characters a bit better (though the internal display is great, it's a bit small). Another possibility would be to hook the thing to the video in jack on one of my graphic cards on desktop. -- John.