Presented toMd. Rifat Ahmmad Rashid,

Lecturer, Department of CIS, Bangladesh University of Business & Technology

Presented by

1. nameI.D. No. 1011310….2. nameI.D. No. 1011310….

OverviewIntroductionComputer capacityTypes of memoryMain memoryTypes of main memoryTypes of main memory deviceSecondary memoryTypes of secondary memory deviceImportant Secondary Storage MethodsSecondary storage devicesHard disksSome regular usable discsOther types of secondary storageReferences

Introduction Memory is a device that is used to store data or programs on

a temporary or permanent basis for use in an electronic digital computer.

The memory is needed for the following purposes:

1. To store the program and data during execution2. To store the program for repetitive use3. To store the data for future or periodical use4. To store the result of execution

Computer capacity

Bit: Short for binary digit (0s and 1s), the only data that a CPU(Central Processing Unit) can process.

Byte: An 8-bit string of data, needed to represent any one alphanumeric character or simple mathematical operation.

Types of memory

There are three categories of computer memories:

Main Memory (Primary Memory) stores small amounts of data and information that will be immediately used by the CPU (Central Processing Unit).

Secondary Memory (Auxiliary or Backup) stores much larger amounts of data and information (an entire software program, for example) for extended periods of time.Internal Processor Memory stores temporary storage of instruction and data used as working registers.

Main memoryMain memory is a large array of data or bytes. It provides

storage that can be access directly by the CPU.

Major activity of main memory:

1. Keep track of which part of memory currently being used and by whom.2. Decide which process are loaded into memory when memory space becomes available.3. Allocate reallocate memory space as needed.

Types of main memory

Semiconductor Memory Semiconductor memory uses semiconductor-based

integrated circuits to store information. Both volatile and non-volatile forms of semiconductor memory exist.

Magnetic MemoryMagnetic storage uses different patterns of magnetization on a magnetically coated surface to store information. Magnetic storage is non-volatile.

Types of main memory device

Main Memory

ROM RAM Cache Register

Random access memory (RAM): The part of primary storage that holds a software program and small amounts of data when they are brought from secondary storage. Rams are categorised as follows: – SRAM (Static RAM) (flip-flop gates)– DRAM (Dynamic RAM)

Types of Main Memory Device

Read-only memory (ROM): Type of primary storage where certain critical instructions are safeguarded; the storage is nonvolatile and retains the instructions when the power to the computer is turned off. ROMs are categorised as follows: – PROM (programmable)– EPROM (erasable programmable)– EEPROM (electronically erasable

programmable)

Types of Main Memory Device

Types of Main Memory Device Cache memory: A type of primary storage

where the computer can temporarily store blocks of data used more often.

Register: registers are part of the CPU with the least capacity, storing extremely limited amounts of instructions and data only immediately before and after processing.

Secondary Memory Memory capacity that can store very large

amounts of data for extended periods of time.– It is nonvolatile.– It takes much more time to retrieve data

because of the electromechanical nature. – It is cheaper than primary storage.– It can take place on a variety of media– It is permanent memory

Secondary Storage

Magnetic Tape Magnetic Disk CD-ROM

Hard Disk Floppy Disk

Types of Secondary Storage Device

• Magnetic Disk Drive• Floppy Disk Drive• Magnetic Tape Drive• Optical Disk Drive

Important Secondary Storage Methods

Most desktop microcomputer systems have floppy disks, hard disks optical disk drives and High Capacity Floppy Disks.

Secondary Storage Devices

High Capacity Floppy Disks

There are three types of hard disks:– Internal

– Hard-disk cartridge– Hard-disk pack

Hard Disks

Hard-disk cartridge

Some regular usable discsTraditional Floppy Disk

Optical Disks

Compact Disc

Other Types of Secondary Storage

• Solid-state storage Flash memory cards Key chain hard drives

• Internet hard drives

• Magnetic tape

ReferencesNorton,P.(2010-2011) “Introduction to Computer”, 9th edition, Tata McGraw-Hill

Sarker & Gupta,(2005),“Elements of Computer Science”,2nd edition, S.Chand & Company Ltd.

Ahmmad,R.R, Lecturer, Department of CIS, BUBT

Memory - Wikipedia, the free encyclopedia.htm