# Digital Circuits Questions and Answers – Programmable Logic Array

This set of Digital Electronics/Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Programmable Logic Array”.

1. What is memory decoding?
a) The process of Memory IC used in a digital system is overloaded with data
b) The process of Memory IC used in a digital system is selected for the range of address assigned
c) The process of Memory IC used in a digital system is selected for the range of data assigned
d) The process of Memory IC used in a digital system is overloaded with data allocated in memory cell

Explanation: The Memory IC used in a digital system is selected or enabled only for the range of addresses assigned to it and this process is called memory decoding. It decodes the memory to be selected for a specific address.

2. The first step in the design of memory decoder is __________
a) Selection of a EPROM
b) Selection of a RAM
d) Data insertion

Explanation: Memory decoder decodes the memory to be selected for a specific address. The first step in the design of memory decoder is address assignment in non-overlapped manner.

3. How many address bits are required to select memory location in the Memory decoder?
a) 4 KB
b) 8 KB
c) 12 KB
d) 16 KB

Explanation: Memory decoder decodes the memory to be selected for a specific address. Since the given EPROM and RAM are of 4 KB (4 * 1024 = 4096) capacity, it requires 12 address bit to select one of the 4096 memory locations.

4. How memory expansion is done?
a) By increasing the supply voltage of the Memory ICs
b) By decreasing the supply voltage of the Memory ICs
c) By connecting Memory ICs together
d) By separating Memory ICs

Explanation: Memory ICs can be connected together to expand the number of memory words or the number of bits per word.

5. IC 4116 is organised as _________
a) 512 * 4
b) 16 * 1
c) 32 * 4
d) 64 * 2

Explanation: IC 4116 is organised as 16 * 1 K which has capability to store 16 KB.

6. To construct 16K * 4-bit memory, how many 4116 ICs are required?
a) 1
b) 2
c) 3
d) 4

Explanation: Since, IC 4116 is organised as 16K * 1, which can store about 16KB data. So, four ICs are required for 16K * 4 memory implementation.

7. How many 1024 * 1 RAM chips are required to construct a 1024 * 8 memory system?
a) 4
b) 6
c) 8
d) 12

Explanation: One 1024 * 1 RAM chips is of 1-bit. SO, for construction of 1024 * 8 RAM chip of 8-bits, it will require 8 chips.

8. How many 16K * 4 RAMs are required to achieve a memory with a capacity of 64K and a word length of 8 bits?
a) 2
b) 4
c) 6
d) 8

Explanation: 16K * 4 = 64K RAM is of 64K. Therefore, for a word of length 8-bits,
64 * 8 = 512K RAM required. Thus, number of 16K * 4 RAMs = 512/64 = 8.

9. The full form of PLD is _________
b) Programmable Logic Data
c) Programmable Logic Devices

Explanation: The full form of PLD is Programmable Logic Devices. It is a collection of gates, flip-flops and registers on a single chip.

10. PLD contains a large number of _________
a) Flip-flops
b) Gates
c) Registers
d) All of the Mentioned

Explanation: Programmable Logic Devices is a collection of a large number of gates, flip-flops, registers that are interconnected on the chip. Thus, it is used for designing logic circuits.

11. Logic circuits can also be designed using _________
a) RAM
b) ROM
c) PLD
d) PLA

Explanation: Programmable Logic Devices is a collection of large number of gates, flip-flops, registers that are interconnected on the chip. Thus, it is used for designing logic circuits.

12. In PLD, there are provisions to perform interconnections of the gates internally, because of _________
a) High reliability
b) High conductivity
c) The desired logic implementation
d) The desired output

Explanation: Programmable Logic Devices is a collection of a large number of gates, flip-flops, registers that are interconnected on the chip. In PLD, there are provisions to perform interconnections of the gates internally so that the desired logic can be implemented.

13. Why antifuses are implemented in a PLD?
a) To protect from high voltage
b) To increase the memory
c) To implement the programmes
d) As a switching devices

Explanation: Programmable Logic Devices is a collection of a large number of gates, flip-flops, registers that are interconnected on the chip. Programming is accomplished by using antifuses in a PLD and it is fabricated at the cross points of the gates.

14. How many types of PLD is?
a) 2
b) 3
c) 4
d) 5

Explanation: There are two types of PLD, viz., devices with fixed architecture and devices with a flexible architecture. The main categories of PLDs are PROM, PAL and PLA.

15. PLA refers to _________
b) Programmable Array Logic
c) Programmable Logic Array
d) Programmed Array Logic

Explanation: PLA refers to Programmable Logic Array. It is a type of PLD having programmable AND and OR gates.

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