Direct-coupled transistor logic

A special type of resistor–transistor logic (RTL) , a direct-coupled transistor logic or DCTL gate is one wherein the bases of the transistors are connected directly to inputs without any base resistors. Without the base resistors, DCTL gates are more economical and simpler to fabricate onto integrated circuits than RTL gates with base resistors. Unfortunately, DCTL has a high susceptibility to ground noise and requires consistent transistor characteristics.[1]

References

^ Roehr (1963, p. 36)

Roehr, William, ed. (1963), Switching Transistor Handbook, Motorola, Inc.