A decoder, a digital circuit is used to point to the specific memory location where the word can be located.

(i) Address Bus
(ii) Control Bus
(iii) Data Bus

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

The Program Counter (PC) is a special register in the CPU which always keeps the  address of the next instruction to be executed.

A command which is given to a computer to perform an operation on data is called an instruction.

(i) RISC stands for Reduced Instruction Set Computers. They have a small set of highly optimized instructions.
(ii) Complex instructions are also implemented using simpler instructions, thus reducing the size of the instruction set.
(iii) Examples of RISC processors are Intel P6, Pentium IV, AMD K6 and K7.

Flash memory devices:
(i) Flash memory is an clectronic (solid-state) non-volatile computer storaye medium that can be electrically erased and reprogrammed.
(ii) Flash memories can be used in personal computers, Personal Digital Assistants (PDA). digital audio players, digital cameras and mobile phones.
(iii) Flash memory offers fast access timcs. The time taken to read or write a character in memory is called access is time.
(iv) Examples for Flash memories arc pen memory drives, cards etc.
EEPROM :
(i) Electrically Erasable Programmable Read Only Memory can be erased by exposing it to an electrical charge.
(ii) EEPROM is non-volatile.
(iii) EEPROM is slower in performance.

(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 init is not permanent. As soon as the power is turned off, whatever data 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) Bus:
A bus is a collection of wires used for communication between the internal components of a computer.
(b) Data bus:
(i) Data busis a collection of wires to carry data in bits.
(ii) A data bus is used to transfer data between the memory and the CPU.
(iii) The data bus is bidirectional.
(c) Address bus:
(i) Address bus is a collection of wires to carry data in bits.
(ii) The address bus is used to point a memory location.
(iii) The address bus is unidirectional.
(d) Control bus:
(i) Control bus is a control line/collection of wires to control the operation/functions.
(ii) The control bus controls both read and write operations.

Read only memory (ROM):
(i) Read Only Memory refers to special memory in a computer with pre-recorded data at manufacturing time which cannot be modified. The stored programs that start the computer and perform diagnostics are available in ROMs.
(ii) ROM stores critical programs such as the program that boots the computer. Once the data has been written onto a ROM chip, it cannot be modified or removed and can only be read.
(iii) ROM retains its contents even when the computer is turned off. So, ROM is called as a non-volatile memory
Programmable Read only memory (PROM):
(i) Programmable read only memory is also a non-volatile memory on which data can be written only once. Once a program has been written onto a PROM, it remains there forever.
(ii) Unlike the main memory, PROMs retain their Contents even when the computer is turned off.
(iii) PROM is manufactured as a blank memory, whereas ROM is programmed during the manufacturing process itself. PROM programmer or a PROM burner is used to write data to a PROM chip. The process of programming a PROM is called burning the PROM.
Erasable Programmable Read-only memory (EPROM):
(i) Erasable Programmable Read-Only Memory is a special type of memory which serves as a PROM. The content can be erased using ultraviolet rays.
(ii) An EPROM differs from a PROM. PROM can be written only once and cannot be erased.
(iii) EPROMs are used widely in personal computer, because they enable the manufacturer to change the contents of the PROM to replace with updated versions or erase the contents before the computer is delivered.
Electrically Erasable Programmable Read-Only Memory (EEPROM)
(i) Electrically Erasable Programmable Read-Only Memory can be erased by exposing it to an electrical charge.
(ii) Like other types of PROM, EEPROM retains its contents even when the power is turned off. Comparing with all other types of ROM, EEPROM is slower in performance.

A memory is just like a human brain. It is used to store data and instructions. Computer memory is the storage space in the computer, where data and instructions are stored. There are two types pf accessing methods to access (read or write) the memory.

They are sequential access and random access. In sequential access, the memory is accessed in an orderly manner from starting to end. But, in random access, any byte of memory can be accessed directly without navigating through previous bytes. Different memory devices are arranged according to the capacity, speed and cost as shown in Figure.