Another thing that Gilbert was responsible for was the Tek 7000-series readout. Tek were ready to go with the same fibre-optic scheme they used in the 576 curve tracer, and even had four holes moulded in the top of the rear frame of the plugins, and mating holes in the edge connector mouldings in the mainframe.
Gilbert reckoned it was madness, so he built a character generator that wrote the readout onto the CRT screen mutiplexed with the trace. Out of discrete logic - probably a whole bucket load of TTL. He won the day, the implementation was then put onto custom chips, and that is what the entire 4-bay, and 3-bay 7000-series used.
The holes still remained however (and were a bit of a mystery unless you knew the history), right to the end of the 7000 series life. There was only one plugin that actually used them - for coax connections; that was the 7A21N direct access plugin. That is a highly specialised unit that connects the GR874 input sockets (+ and - differential, or single ended by rewiring coaxes) directly to the CRT vertical deflection plates. You have to physically move the y-amp backwards in the chassis, and then add passive boards that replaces the y-amp. Lousy sensitivity (4V/div single ended 10V/div differential, approx), but you get one hell of a bandwidth! 20kHz to >1GHz from a 7904.
Gilbert reckoned it was madness, so he built a character generator that wrote the readout onto the CRT screen mutiplexed with the trace. Out of discrete logic - probably a whole bucket load of TTL. He won the day, the implementation was then put onto custom chips, and that is what the entire 4-bay, and 3-bay 7000-series used.
The holes still remained however (and were a bit of a mystery unless you knew the history), right to the end of the 7000 series life. There was only one plugin that actually used them - for coax connections; that was the 7A21N direct access plugin. That is a highly specialised unit that connects the GR874 input sockets (+ and - differential, or single ended by rewiring coaxes) directly to the CRT vertical deflection plates. You have to physically move the y-amp backwards in the chassis, and then add passive boards that replaces the y-amp. Lousy sensitivity (4V/div single ended 10V/div differential, approx), but you get one hell of a bandwidth! 20kHz to >1GHz from a 7904.
