# Digital Circuits Questions and Answers – Transistor Transistor Logic(TTL)

This set of Digital Electronics/Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Digital Circuits Questions and Answers – Transistor Transistor Logic(TTL or T2L)”.

1. Transistor–transistor logic (TTL) is a class of digital circuits built from ____________
a) JFET only
b) Bipolar junction transistors (BJT)
c) Resistors
d) Bipolar junction transistors (BJT) and resistors

Explanation: Transistor–transistor logic (TTL) is a class of digital circuits built from bipolar junction transistors (BJT) and resistors. However, resistors have a small role to play and both logic gating and amplifying functions are performed by the transistors.

2. TTL is called transistor–transistor logic because both the logic gating function and the amplifying function are performed by ____________

a) Resistors
b) Bipolar junction transistors
c) One transistor
d) Resistors and transistors respectively

Explanation: TTL is called transistor–transistor logic because both the logic gating function and the amplifying function are performed by bipolar junction transistors (BJTs).

3. TTL was invented in 1961 by ____________
a) Baker clamp
b) James L. Buie
c) Chris Brown
d) Frank Wanlass

Explanation: TTL was invented in 1961 by James L Buie.

4. The full form of TCTL is ____________
a) Transistor-coupled transistor logic
b) Transistor-capacitor transistor logic
c) Transistor-complemented transistor logic
d) Transistor-complementary transistor logic

Explanation: The full form of TCTL is transistor-coupled transistor logic.

5. The _______ ancestor to the first personal computers.
a) PARAM 1
b) SATYAM 1
c) KENBAK 1
d) MITS Altair

Explanation: The KENBAK 1, ancestor to the first personal computers.

6. TTL inputs are the emitters of a ____________
a) Transistor-transistor logic
b) Multiple-emitter transistor
c) Resistor-transistor logic
d) Diode-transistor logic

Explanation: TTL inputs are the emitters of a multiple-emitter transistor.

7. TTL is a ____________
a) Current sinking
b) Current sourcing
c) Voltage sinking
d) Voltage sourcing

Explanation: Like DTL, TTL is a current-sinking logic since a current must be drawn from inputs to bring them to a logic 0 level. Current Sink means it accepts current coming out from a source.

8. Standard TTL circuits operate with a __ volt power supply.
a) 2
b) 4
c) 5
d) 3

Explanation: Standard TTL circuits operate with a 5-volt power supply.

9. TTL devices consume substantially ______ power than equivalent CMOS devices at rest.
a) Less
b) More
c) Equal
d) Very High

Explanation: TTL devices consume substantially more power than equivalent CMOS devices at rest. Thus, CMOS devices are faster than TTL devices.

10. A TTL gate may operate inadvertently as an ____________
a) Digital amplifier
b) Analog amplifier
c) Inverter
d) Regulator