Hi Folks, I finally got something that I've been after for a long time. It's a Tektronix System Test Fixture, PN 067-0746-00. It's for the Tektronix 4051 computer, 4662 Plotter, 4924 Tape unit and other Tektronix items that use the 6800 CPU. It's a box with switches and indicator lights that lets you halt the system CPU and view and change the contents of any memory location, single step the system, etc. You can also set it to halt the system when it gets to a certain address or when a certain data word occurrs. It also contains a ROM with test routines for the 40551 computer. A friend of mine found this at a flea market and I've been trying to get it away from him for months. My persistance finally paid off. Joe