Computer Memory Types

Cache Memory

• Cache memory is a special type of internal memory used by many CPUs.
• It is like a memory register but outside of the CPU.

Registers, Cache Memory, and Main Memory

• Registers are inside the CPU and used to store instructions and data when processed.
• Cache memory is a faster and smaller memory that stores frequently used data.
• Main memory has the programs that are currently being run and the operating system's data.

Secondary Storage Devices

• Secondary memory is external memory with higher storage capacity.
• It is not directly accessible to the CPU.
• Examples of secondary storage devices include:
  • Floppy disk
  • Hard disk
  • Magnetic tape
  • CD
  • DVD
  • ROM (Read Only Memory)

Magnetic Storage Devices

• Magnetic devices are coated with a magnetically sensitive material.
• They use magnetic charges to represent 1 and 0.
• Examples of magnetic storage devices include:
  • Floppy disk
  • Hard disk
  • Magnetic tape

Optical Storage Devices

• Optical storage devices use a laser beam to read data on plastic or metallic disks.
• 1 and 0 are represented by flat areas called lands and pits.
• Examples of optical storage devices include:
  • CD
  • DVD

Types of CDs and DVDs

• CD-ROM (Compact Disc Read Only Memory)
• CD-R (Compact Disc Recordable)
• CD-RW (Compact Disc Re Writable)
• DVD-ROM (Digital Versatile Disc Read Only Memory)
• DVD-R (DVD Recordable)
• DVD-RAM (DVD Random Access Memory)
• DVD-RW (DVD Re Writable)

Solid State Storage Devices

• Solid state storage devices use integrated circuits to store data.
• They store data electronically as 1 and 0.
• Data reads and writes very quickly.
• Examples of solid state storage devices include:
  • Flash memory
  • Smart cards
  • Solid state disks (SSD)

Monitors

• Three main types of monitors include:
  • Cathode ray tube (CRT) monitor
  • Flat panel monitor (Liquid Crystal Display (LCD))
  • LED monitor

Projector

• A multimedia projector is a compact, high-resolution, full-color projector.
• It is used to project text, images, video, and audio content.
• It is commonly used in classrooms and auditoriums for slide presentations.

Printer

• A printer is used to get processed information on paper (hard copies).
• Examples of printers include:
  • Ink-Jet printer
  • Laser printer
  • Dot-Matrix printer

Speakers, Headphone, and Headset

• A speaker is the key output device of sound.
• A sound system includes speakers and a sound card.

Memory Unit

• There are two types of storage:
  • Primary storage memory
  • Secondary storage memory

Primary Storage

• Primary storage memory is directly connected to the CPU.
• There are three types of primary storage:
  • Processor registers
  • Main memory (RAM)
  • Cache memory

Central Processing Unit (CPU)

• The CPU contains electronic circuits that process instructions.
• It interprets instructions and performs logical and arithmetic operations.
• It is the "brain" of the computer.
• The CPU can perform:
  • Calculations
  • Comparisons
  • Logical decisions

Components of the CPU

• Control unit (CU)
• Arithmetic logic unit (ALU)
• Memory unit (MU)

Control Unit

• It coordinates the sequence of data flow between the processor and memory units.
• It controls data flow inside the processor.
• It obtains instructions from the memory and communicates with input/output devices.

Arithmetic Logic Unit (ALU)

• It performs arithmetic operations like addition, subtraction, multiplication, and division.
• It performs logic operations like comparing, selecting, matching, and merging data.

Memory Unit

• The memory inside the CPU is called a register (CPU register).
• It is a small set of data holding places that are part of the computer processor.
• The memory in the CPU (CPU register) stores all data and/or instructions that are currently being processed on the CPU.

Operation of CPU

• The fundamental operation of the CPU is to execute a sequence of stored instructions, called a program.
• There are four steps in the executing cycle:
  • Fetch
  • Decode
  • Execute
  • Write back (Store)