squalyl (./7614) :
c'était pas 20mA?

Ça a changé, en fait :

https://en.wikipedia.org/wiki/Digital_current_loop_interface#History :
Older teleprinters used a 60 mA current loop. Later machines, such as the Teletype Model 33, operated on a lower 20 mA current level and most early minicomputers featured a 20 mA current loop interface, with an RS-232 port generally available as a more expensive option.