Decade Counter Identification

The question asks to identify which integrated circuit (IC) functions as a decade counter from the given options. A decade counter, also known as a divide-by-10 counter or a Binary-Coded Decimal (BCD) counter, is a type of counter that counts through ten states, typically represented by the decimal numbers 0 through 9. After reaching the 9th state, it resets to the 0 state, completing its cycle.

Analyzing Counter IC Options

Let's examine each option to determine its function:

• IC 7493: This is a 4-bit asynchronous binary counter. It can count from 0 to 15 (0000 to 1111 in binary). Since it counts 16 states, it is not a decade counter.
• IC 7490: This IC is specifically designed as a decade counter (BCD counter). It is composed of two separate counters which can be connected to form a 4-bit decade counter. It counts from 0 to 9 and then resets. This matches the definition of a decade counter.
• IC 7491: This is an 8-bit serial-in, parallel-out shift register. Shift registers are used for data storage and manipulation, not counting. Therefore, it is not a counter.
• IC 7492: This is a divide-by-12 counter (also known as a MOD-12 counter). It counts through 12 states (e.g., 0 to 11), not 10. Thus, it is not a decade counter.

Conclusion on Decade Counter

Based on the analysis of the functions of each IC:

• IC 7493 is a 4-bit binary counter.
• IC 7490 is a decade counter (BCD counter).
• IC 7491 is a shift register.
• IC 7492 is a divide-by-12 counter.

Therefore, the IC that represents a decade counter is the IC 7490.