Chapter 6: Logic Circuits
7. Why are NAND and NOR gates called Universal Gates? (3 Marks)
Versatility: They are called universal because any basic logic gate (AND, OR, NOT) can be constructed using only NAND gates or only NOR gates.
Cost: It is often cheaper and easier for manufacturers to use only one type of gate to build complex circuits.
8. Explain the 7-Segment Display and its types. (4 Marks)
Function: An arrangement of 7 LEDs (a to g) used to display decimal numerals (0-9).
Common Cathode (CC): All negative terminals are joined; a segment lights up when it receives a HIGH (1) signal.
Common Anode (CA): All positive terminals are joined; a segment lights up when it receives a LOW (0) signal.
9. Define a Decade Counter and name a common IC used for it. (3 Marks)
Definition: A digital circuit that counts from 0 to 9 (ten states) and then resets back to 0.
IC Used: IC 7490 is the most common decade counter.
Usage: Found in digital clocks, frequency counters, and timers.
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