Transistor inverter logic...

How come i never see "use a pnp transistor" ? Price? Cheaper ti manufacture npn?

PNP transistors are slower than NPN, that's why.

(actually there is also historical bias towards strong pull-down logic gates due to TTL families)

it could well hark back to the fact that early PNP transistors were pretty leaky as they were Geranium based
NPN using Silicon were much better

mmcp42:
it could well hark back to the fact that early PNP transistors were pretty leaky as they were Geranium based
NPN using Silicon were much better

Well surely the choice was between silicon PNP and NPN then? After all the fact that thermionic
valves are all n-type didn't cross over into the semiconductor world...

nope in the beginning PNP silicon had such lousy gain that you had to use germanium