With plug-in units:
7A18 Dual trace amplifier
7A26 Dual trace amplifier
7B53A Dual time base
Additional plug-ins in cart:
7B71 Delaying Time Base
5B12N Dual time base
5A26 Dual Differential Amplifier
7D15 Counter Timer
Functionality: Time Code Generator/Reader/Tape Search and Control Unit.
(1) for use in time-indexing during data acquisition; (2) decodes incoming modulated code during data playback; (3) operates as a fully automatic tape search system.
"The birth of the Time Domain Reflectometry at HP came with the 1415A drawer in the 140A mainframe, introduced in the September 1963 of the Hewlett Packard Journal.