This document discusses different types of computer memory. It describes main memory, which is used for immediate access by the CPU, and secondary memory, which stores much larger amounts of data for longer periods. The main types of main memory are RAM, ROM, cache, and registers. RAM and ROM are further divided into static, dynamic, programmable, erasable, and electronically erasable types. Secondary memory includes magnetic disks, tapes, CD-ROMs, and solid-state storage. Hard disks can be internal, removable cartridges, or disk packs.

1. Presented to
Md. Rifat Ahmmad Rashid,
Lecturer, Department of CIS,
Bangladesh University of Business & Technology

2. Presented by
1. name
I.D. No. 1011310….
2. name
I.D. No. 1011310….

3. Overview
Introduction
Computer capacity
Types of memory
Main memory
Types of main memory
Types of main memory device
Secondary memory
Types of secondary memory device
Important Secondary Storage Methods
Secondary storage devices
Hard disks
Some regular usable discs
Other types of secondary storage
References

4. 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 execution
2. To store the program for repetitive use
3. To store the data for future or periodical use
4. To store the result of execution

5. 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.

6. 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.

7. Main memory
Main 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.

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

9. Types of main memory device
Main Memory
ROM RAM Cache Register

10. 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

11. 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

12. 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.

13. 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

14. Secondary Storage
Magnetic Tape Magnetic Disk CD-ROM
Hard Disk Floppy Disk
Types of Secondary Storage Device

15. • Magnetic Disk Drive
• Floppy Disk Drive
• Magnetic Tape Drive
• Optical Disk Drive
Important Secondary Storage Methods

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

17. There are three types of hard disks:
– Internal
– Hard-disk cartridge
– Hard-disk pack
Hard Disks
Hard-disk
cartridge

18. Some regular usable discs
Traditional Floppy Disk
Optical Disks
Compact
Disc

19. Other Types of Secondary Storage
• Solid-state storage
 Flash memory cards
 Key chain hard drives
• Internet hard drives
• Magnetic tape

20. References
Norton,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