View source for 3S5

The Tektronix Type 3S5 is a [[sampling oscilloscope|sampling]] time base plug-in [[introduced in 1968]]
for [[560-series scopes]].  It takes two S-series sampling
heads such as the [[S1]], [[S2]], [[S3]]. [[S4]], [[S5]], or [[S6]].  It is particularly designed
to be used in [[567]] and [[568]] scopes, where it is programmable and provides signals that inform the digital unit 
of the scale factor and units, depending on what sampling head is inserted.

* http://w140.com/tektronix_3s5.pdf