Computer Peripheral Devices and Memory Systems

Computer Peripheral Devices

• A CPU is not a peripheral device; it's the central processing unit.
• A keyboard, monitor, and mouse are all peripheral devices.

System Unit Ports

• A port allows data transfer between various devices and the computer.

Computer Memory (ROM)

• ROM (Read-Only Memory) is memory where users cannot write new information or instructions.

Groups of Bits

• A Byte is a group of 8 bits.

Megabytes and Bytes

• A megabyte (MB) is equal to 1024 * 1024 bytes.

Device Drivers

• Device drivers allow input and output devices to communicate with the computer system.

Computer Memory Types

• Primary memory is also known as main memory.
• Secondary memory is separate from main memory.

Optical Disks

• A CD is a non-erasable disk for storing digitized audio information.

Outputting Data

• Outputting data produces useful information for the user.

Output Units

• The output unit transforms user-entered data into a computer-readable format.

Data Input/Output

• Input is the raw materials used in data processing operations. The processed data becomes the output.

Computer Characteristics

• I.Q. is not a characteristic of a computer.
• Speed, accuracy, capacity, and reliability are computer characteristics.

Computer Memory

• Memory is an electronic storage for data retrieval.

Memory Size

• The size of main memory depends on the address bus size.
• Secondary memory is independent of the address bus.

Memory Address Register (MAR)

• MAR stands for Memory Address Register.

Optical Disks - Storage Capacity

• Storage capacity of optical disks is calculated by multiplying the number of sectors by the number of bytes per sector.

Disk Rotation

• The disk rotation speed varies inversely with the radius of the disk.

Disk Sectors

• Sectors on the disk have a constant size.

Optical Disk Access Times

• Typical access times for optical disks range between 100 to 300 milliseconds.

Optical Disk Technology

• The technology used in optical disks is laser beam.

Computer Input Devices

• Input devices read data and instructions from the outside world.
• Input devices do not convert data into user-understandable formats.

Types of Computer Users

• End-users are computer users who aren't computer professionals.

Computer Classifications

• A maxicomputer is not a computer type.
• Mainframes, microcomputers, notebook computers, and supercomputers are computer classifications.

Most Powerful Computers

• Supercomputers are the most powerful computers.

Binary System

• Data is represented in computers using the binary system, which is a two-state (on/off) system.

Data Representation

• A bit represents a letter, digit, or special character.

Capacity Measurement

• Memory is measured in terms of megabytes.

Cache Memory

• Cache memory is a type of memory built into the CPU chip.

Processor Speed

• Processor speed is measured in megahertz (MHz).

Screen Display Metrics

• Dot pitch is the distance between pixels on a screen.

Screen Symbols

• Icons are pictorial symbols that represent computer activities.

Image Display Forms

• Screen output displays images in a soft copy format.

Optical Character Recognition (OCR) Devices

• Wand readers are devices for optical character recognition.

Mark Sensing Devices

• OMR stands for Optical Mark Recognition.

Screen Refresh Rate

• The rate of screen refreshment is called raster rate.