The Tektronix 7A12 is a 120 MHz dual-trace vertical plug-in for 7000-series scopes. It was designed by Roy Hayes (who also designed the 3A3 before leaving for HP Loveland in Jan 1971). The Evaluation Engineer for the 7A12 was Peter Starič, co-author of the book "Wideband Amplifiers" with Erik Margan. The 7A12 has relays in the signal path for the input attenuators. The relays are controlled by logic in the 7A12, which is controlled by switches on the front panel of the 7A12.