Test: Semiconductor Memories - 1

DRAM:

•  In a DRAM, a capacitor to store a bit of data is used along with a MOSFET (transfer device) which acts as a switch.
• It requires only one transistor to store one-bit data whereas SRAM requires 6 transistors.
• The information is stored in a capacitor.
• Both read and write operations cannot be performed simultaneously.
• To store one bit of data, DRAM needs one transistor and one capacitor.
• Since the capacitor stores the data in the form of charge.
• To keep the charge stored for a long duration, the capacitor needs to constantly be refreshed. So DRAM is slower and used for main memory.

1. NIC is used to connect a computer to an Ethernet network.
2.The card usually contains the protocol control firmware and the Ethernet controller needed to support Medium Access control (MAC).
3. A MAC address is given to a network adapter. It is a hardware into the computer Network interface card (NIC) and is also unique.
4. It is a six-byte or 48-bit address that uniquely identifies the Ethernet-based connection.

Concept:

Memory Chips:

• The number of address pins is related to the number of memory locations.
• The data pins are typically bi-directional in read-write memories. The number of data pins is related to the size of the memory location.

Given that, 

Address pins= 24 (is related to the number of memory locations)

Data pins= 16 (It is related to the size of the memory location)

So For 'N-Bits' address pins, the number of locations that will accommodate is 2^N.

So For '24-Bits' address pins, the number of locations that will accommodate is 224.

Hence the correct answer is 224.

The conversion of memory is given below.

1 TB = 1024 GB

1 GB = 1024 MB

1 MB = 1024 kB

1 kB = 1024 Byte

1 Byte = 8 bits

Concept:

• EPROM and EEPROM is a type of ROM.
• Data in ROM can be accessed randomly and hence EPROM and EEPROM are random access memory.

Important Points:

• EPROM is an erasable programmable read-only memory.
• It is a non-volatile memory that means its data will be retained even when the power is turned off.
• EEPROM (electrically erasable programmable read-only memory) is a user-modifiable read-only memory (ROM) that can be erased and reprogrammed (written to) repeatedly through the application of higher than normal electrical voltage.

In a DRAM, a capacitor to store a bit of data is used along with a MOSFET (transfer device) which acts as a switch. The circuit is as shown –

In a DRAM:

• Periodic refreshing is required.
• The information is stored in a capacitor.
• Both read and write operations cannot be performed simultaneously.

Programmable logic device (PLD):

It is an IC with a large number of logic gates, which is programmed by software to perform a specific digital logic function. And it can be changed according to the application.

Examples: PLA, PAL, FPLA, PROM, GAL, FPGA, etc.

Fixed functional ICS:

It is an ICs in a compact form that is designed to perform for fixed logic applications and it can not be changed after manufacture.

Examples: IC-555, IC-741, Johnson counter, full adder, parallel adder, etc.

Advantages of PLD over fixed functional ICs:

So, the correct option is D.

Concept:

Address line: An address line is basically refers to a physical connection between a CPU/Chipset and memory. They specify which addresses to access in memory. When there are k address lines, then 2k memory word can be accessed.

Data line: Data lines provides the information to be stored in memory. It represents the number of bits in the word.

Calculation:

Here, it is given that memory unit size = 256 bytes

2^k = 256

k = 8

1. A bit is the smallest unit of storage.
2. A bit stores just a 0 or 1.
3. Computers are designed to store data and execute instructions in bit multiples called bytes.
4. One byte is equal to 8 bits.

EPROM (Erasable programmable read-only memory):

• EPROM stands for erasable programmable read-only memory.
• EPROM is a nonvolatile kind of memory.
• If ultraviolet rays are exposing (Mercury –vapor light) to the EPROM chip, then this chip will release stored charge. The stored content in that EPROM chip will be lost or erased.