1. Explain ROM
A read only memory(ROM) is a device that includes both the decoder and the OR gates within a
single IC package. It consists of n input lines and m output lines. Each bit combination of the input
variables is called an address. Each bit combination that comes out of the output lines is called a
word. The number of distinct addresses possible with n input variables is 2n.
2. What are the types of ROM?
1.PROM 2.EPROM 3.EEPROM
3. Explain PROM.
PROM (Programmable Read Only Memory) It allows user to store data or program. PROMs use the
fuses with material like nichrome and polycrystalline. The user can blow these fuses by passing
around 20 to 50 mA of current for the period 5 to 20μs.The blowing of fuses is called programming
of ROM. The PROMs are one time programmable. Once programmed, the information is stored
permanent.
4. Explain EPROM.
EPROM(Erasable Programmable Read Only Memory) EPROM use MOS circuitry. They store 1’s and
0’s as a packet of charge in a buried layer of the IC chip. We can erase the stored data in the EPROMs
by exposing the chip to ultraviolet light via its quartz window for 15 to 20 minutes. It is not possible
to erase selective information. The chip can be reprogrammed.
5. Explain EEPROM.
EEPROM(Electrically Erasable Programmable Read Only Memory) EEPROM also use MOS circuitry.
Data is stored as charge or no charge on an insulated layer or an insulated floating gate in the
device. EEPROM allows selective erasing at the register level rather than erasing all the information
since the information can be changed by using electrical signals.
6. What is RAM?
Random Access Memory. Read and write operations can be carried out.
7. Define ROM
A read only memory is a device that includes both the decoder and the OR gates within a single IC
package.
8. Define address and word:
In a ROM, each bit combination of the input variable is called on address. Each bit combination that
comes out of the output lines is called a word.
9. What are the types of ROM.
1. Masked ROM. 2. Programmable Read only Memory 3. Erasable Programmable Read only memory.
4. Electrically Erasable Programmable Read only Memory.
10. What is programmable logic array? How it differs from ROM?
In some cases the number of don’t care conditions is excessive, it is more economical to use a
second type of LSI component called a PLA. A PLA is similar to a ROM in concept; however it does
not provide full decoding of the variables and does not generates all the minterms as in the ROM.
11.What is mask - programmable?
With a mask programmable PLA, the user must submit a PLA program table to the manufacturer.
12. What is field programmable logic array?
The second type of PLA is called a field programmable logic array. The user by means of certain
recommended procedures can program the EPLA.
13. List the major differences between PLA and PAL PLA:
Both AND and OR arrays are programmable and Complex Costlier than PAL PAL AND arrays are
programmable OR arrays are fixed Cheaper and Simpler
14. Define PLD.
Programmable Logic Devices consist of a large array of AND gates and OR gates that Can be
programmed to achieve specific logic functions.
A read only memory(ROM) is a device that includes both the decoder and the OR gates within a
single IC package. It consists of n input lines and m output lines. Each bit combination of the input
variables is called an address. Each bit combination that comes out of the output lines is called a
word. The number of distinct addresses possible with n input variables is 2n.
2. What are the types of ROM?
1.PROM 2.EPROM 3.EEPROM
3. Explain PROM.
PROM (Programmable Read Only Memory) It allows user to store data or program. PROMs use the
fuses with material like nichrome and polycrystalline. The user can blow these fuses by passing
around 20 to 50 mA of current for the period 5 to 20μs.The blowing of fuses is called programming
of ROM. The PROMs are one time programmable. Once programmed, the information is stored
permanent.
4. Explain EPROM.
EPROM(Erasable Programmable Read Only Memory) EPROM use MOS circuitry. They store 1’s and
0’s as a packet of charge in a buried layer of the IC chip. We can erase the stored data in the EPROMs
by exposing the chip to ultraviolet light via its quartz window for 15 to 20 minutes. It is not possible
to erase selective information. The chip can be reprogrammed.
5. Explain EEPROM.
EEPROM(Electrically Erasable Programmable Read Only Memory) EEPROM also use MOS circuitry.
Data is stored as charge or no charge on an insulated layer or an insulated floating gate in the
device. EEPROM allows selective erasing at the register level rather than erasing all the information
since the information can be changed by using electrical signals.
6. What is RAM?
Random Access Memory. Read and write operations can be carried out.
7. Define ROM
A read only memory is a device that includes both the decoder and the OR gates within a single IC
package.
8. Define address and word:
In a ROM, each bit combination of the input variable is called on address. Each bit combination that
comes out of the output lines is called a word.
9. What are the types of ROM.
1. Masked ROM. 2. Programmable Read only Memory 3. Erasable Programmable Read only memory.
4. Electrically Erasable Programmable Read only Memory.
10. What is programmable logic array? How it differs from ROM?
In some cases the number of don’t care conditions is excessive, it is more economical to use a
second type of LSI component called a PLA. A PLA is similar to a ROM in concept; however it does
not provide full decoding of the variables and does not generates all the minterms as in the ROM.
11.What is mask - programmable?
With a mask programmable PLA, the user must submit a PLA program table to the manufacturer.
12. What is field programmable logic array?
The second type of PLA is called a field programmable logic array. The user by means of certain
recommended procedures can program the EPLA.
13. List the major differences between PLA and PAL PLA:
Both AND and OR arrays are programmable and Complex Costlier than PAL PAL AND arrays are
programmable OR arrays are fixed Cheaper and Simpler
14. Define PLD.
Programmable Logic Devices consist of a large array of AND gates and OR gates that Can be
programmed to achieve specific logic functions.
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