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Transistors in TTL logic use mA of input current because they're bipolar, not FET transistors.

In classic TTL the input currents are also very asymmetric, e.g. for a high level you mustn't draw more than a few dozen µA out of an input, for a low level you have to draw something like 1.5 mA or so.

This is different from current-steering based logic (all kinds of ECL, including CML/SCL) were the current in the circuit stays the same, but only takes a different path depending on state. Supply current is largely independent of circuit state with these.

That's true, but we're talking about computers here. Computer chips don't use TTL, they're all CMOS, which uses FETs (MOSFETs to be precise).

CMOS didn't exist when the first transistorized computers were made.

Ah, right. I thought the OP was referring to modern CPUs.

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