CPU

CENTRAL PROCESSING UNIT

CPU (Central Processing Unit) or processor is an important part of every computer system because of its work like a brain for every computer system.

CPU COMPONENTS
CPU components can be classified in the following three categories. 

1. ALU (Arithmetic Logical Unit): This component is responsible to perform all types mathematical operations (+, -, *, /) and logical operations (>, <, ==)

2. CU (Control Unit): This component work like a computer's nervous system and responsible to control all types of internal activities and processing.

3. MU (Memory unit): The 'memory unit' responsible to provide memory space to store temporary data, intermediate result and CPU data during any processing.

COMPUTER MEMORY

Memory stands for storing capacity or storing power and every type of computer memory can be classified into two main categories.

PRIMARY MEMORY
The primary memory is also known as volatile memory because of its store data and information for the temporary purpose.

EXAMPLES

1. RAM (Random Access Memory) 

2. ROM (Read-only Memory) 

RAM (RANDOM ACCESS MEMORY)
RAM is also known as "Volatile Memory" because it is used to store data and instructions for the temporary purpose.

TYPES OF RAM
1. Dynamic RAM: The Static RAM require refreshing, therefore its content lost just after a short while (time).

2. Static RAM: These types of  RAMs does not need any refreshment, hence its store data as long system would be power on.

ROM (READ ONLY MEMORY)

ROM is also known as "Non Volatile Memory" because it can store data and instructions for the permanent purpose.

ROM - TYPES
1. PROM (Programmable Read Only Memory): These types of ROM can be written for one time.

2. EPROM (Erasable Programmable ROM): These types of ROM can write more than one time after erasing the previous data.

SECONDARY MEMORY

The Secondary memory is also known as Non-volatile Memory Or 'Auxiliary Memory', because of its store data permanently in the hard drive or in other secondary memory storing devices.

SECONDARY MEMORY - EXAMPLES

1.  HDD (Hard disk drive) also known as Magnetic Disk

2.  FDD (Floppy disk drive) also known as magnetic tape

3.  Pen drive, CDs (Compact Disk)

4.  DVD (Digital Video Disk)

OTHER TYPES MEMORY

CACHE MEMORY
Cache is the fastest memory among all types of memories and it exists between CPU and primary memory.

CACHE MEMORY FEATURES

1. More fastest than compare to any other memory

2. Complex to design.

3. Expensive

4. Very small size


VIRTUAL MEMORY
Virtual memory implemented by the operating system and this technique is used to access secondary memory's space as primary memory. 

MEMORY MEASUREMENT UNITS

Note: ‘Bit’ is smallest measurement unit.

EQUALS TO	UNIT
4 bits	1 nibble
8 bits	1 byte
1024 bytes	1 KB (KiloByte)
1024 KB	1MB (MegaByte)
1024 MB	1 GB (Giga Byte)
1024 GB	1 TB (TeraByte)
1024 TB	1 PB (PetaByte)
1024 PB	1 EB (ExaByte)
1024 EB	1 ZB (ZettaByte)
1024 ZB	1 YB (Yotta Byte)