(i) MAR (Memory Address Register)
(ii) MDR (Memory Data Register)

(i) MHz (Mega Hertz)
(ii) GHz (Giga Hertz)

HDMI (High Definition Multimedia Interface) is an audio/video interface which transfer the uncompressed video and audio data from a video controller, to a compatible computer monitor, LCD projector, digital television, etc.

A program counter (PC) is a CPU register in the computer processor which has the address of the next instruction to be executed from memory. It is a digital counter needed for faster execution of tasks as well as for tracking the current execution point.

Instruction is a command which is given to the computer to perform an operation on a piece of data.

32-bit	64-bit
Data bus is 32-bit wide	Data bus 64-bits wide
Supports maximum of 3-4 GB of memory	It supports more than 4GB
Processing Power is low.	Processing Power is high
Example Pentium IV	Example Core i3, Core i7.

(i) The address bus is used to point a memory location.
(ii) A decoder, a digital circuit is used to point to the specific memory location where the word can be located.
(iii) The address register is connected with the address bus, which provides the address of the instruction.
(iv) A data bus is used to transfer data between the memory and the CPU.
(v) The data bus is bidirectional and the address bus is unidirectional.
(vi) The control bus controls both read and write operations.
(vii) The system bus is a bunch of wires which is the collection of address bus, data bus and control bus that serves as communication channels between the microprocessor and other devices.

Every microprocessor has an internal clock that regulates the speed at which it executes instructions. The speed at which the microprocessor executes instructions is called clock speed. Clock speed is measured in MHz (Mega Hertz) or in GHz (Giga Hertz).

Flash memory	EEPROM
It is faster	It is slower
Flash memory is read/write memory	EEPROM is read only memory
Flash memory can store 4GB to 2TB of data	EEPROM can store only less data
Flash memory is used in PDA'S, Digital camera to store data.	It is used to store critical programs.

Depending upon the size of the data the microprocessor can be classified as
(a) 8 bit microprocessor
(b) 16 bit microprocessor
(c) 4 bit microprocessor
(d) 32 bit microprocessor
(e) 64 bit microprocessor.

The main memory is otherwise called as Random Access Memory. This is available in computers in the form of Integrated Circuits (ICs). It is the place in a computer where the Operating System, Application Programs and the data in current use are kept temporarily so that they can be accessed by the computer's processor. The smallest unit of information that can be stored in the memory is called as a bit. The memory can be accessed by a collection of 8 bits which is called as a byte. The bytes are referred by 'B'. If a computer has 1 megabyte of memory, then it can store 10,48,576 bytes (or characters) of information. [Hence 1MB is 1024K.B and 1 K.Bis 1024 Bytes, So 1024 x 1024 =10,48,576 Bytes).
Types of RAM
There are two basic types of RAM
1. Dynamic RAM (DRAM)
2. Static RAM (SRAM)
These two types differ in the technology they use to hold data. Dynamic RAM being a common type needs to be refreshed frequently. Static RAM needs to be refreshed less often, which makes it faster. Hence, Static RAM is more expensive than Dynamic RAM.

Data communication between CPU and memory
The Central Processing Unit(CPU) has a Memory Data Register (MDR) and a Memory Address Register (MAR). The Memory Data. Register (MDR) keeps the data which is transferred between the Memory and the Cl'U. The Program Counter (PC) is a special register in the CPU which always keeps the address of the next instruction to be executed.

The read operation transfers the data(bits) from word to Memory Data Register. The write operation transfers the data(bits) from Memory Data Register to word.

(i) The main memory is otherwise called as Random Access Memory. This is available in computers in the form of Integrated Circuits ( lCs ). It is the place in a computer where the Operating System, Application Programs and the data in current use are kept temporarily so that they can be accessed by the computer's processor.
(ii) The smallest unit of information that can be stored in the memory is called as a bit. The memory can be accessed by a collection of 8 bits which is called as a byte.
(iii) The bytes are referred by 'B'. If a computer has 1 megabyte of memory, then it can store 10,48,576 bytes.(or characters) of information. [Hence 1MB is 1024KB and 1 KB is 1024 Bytes, So 1024 x 1024 =10,48,576 Bytes].
(iv) RAM is a volatile memory, which means that the information stored in it is not permanent. As soon as the power is turned off, whatever data that resides in RAM is lost. It allows both read and write operations.
(v) There are two basic types of RAM Dynamic RAM (DRAM), Static RAM (SRAM)
(vi) These two types differ in the technology they use to hold data. Dynamic RAM being a common type needs to be refreshed frequently. Static RAM needs to be refreshed less often, which makes it faster.
(vii) Hence, Static RAM is more expensive than Dynamic RAM.

(a) Clock speed-Each microprocessor has an internal clock that regulates the speed at which it executes instructions. The speed at which the microprocessor executes instructions is called clock speed. It is measured in MHz vi in GHz.
(b) Instructions set - The set of machine level instructions that a microprocessor is designed to execute is called as an instruction set. This carries 4 types of operations. They are
1. Data transfer
2. Arithmetic operations
3. Logical Operations
4. Control flow
5. Input/output
(c) Word size - The number of bits that can be processed by a processor in a single instruction is called as its word size. It determines the amount of RAM that can be accessed at one time and the total number of pins on the microprocessor. Total number of input and output pins in turn determines the architecture of the microprocessor.