I first heard the term push-pull to refer to vacuum tube audio or RF
amplifiers where the plates were tied to opposite ends of a transformer
primary, and the supply was connected to the center. Each tube alternately
pulls its end of the transformer to ground. Maybe we should have called it
"pull-pull."

I first heard "totem pole" output referred to in TTL. This output uses a
common emitter NPN transistor to pull the output down, and another NPN
operating as an emitter follower to pull the output up. It resembled a
"totem pole" since the two identical transistors were stacked.

Then, moving in to solid state audio amplifiers, we had the "complementary
emitter follower" where an NPN as an emitter follower pulled the output
up, and a PNP, again as an emitter follower, pulled the output down.
Substituting P channel and N channel FETs for the transistors, we got CMOS
outputs.

So... that's how I recall the terminology.

Harold


-- 
FCC Rules Updated Daily at http://www.hallikainen.com - Advertising
opportunities available!
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist