Computer Science: System Unit Basics

System Unit

• The system unit is the case that contains the computer's electronic components used to process data.
• The motherboard is the main circuit board of the system unit, containing a computer chip with integrated circuits.
• The processor, also called the Central Processing Unit (CPU), interprets and carries out basic instructions that operate a computer.
• The control unit directs and coordinates most of the computer's operations.
• The Arithmetic Logic Unit (ALU) performs arithmetic, comparison, and other operations.
• The processor repeats four basic operations for each instruction. These operations make up a machine cycle.
• Pipelining allows the processor to fetch the second instruction before completing the machine cycle for the first instruction.
• Intel and AMD are the leading manufacturers of personal computer processor chips.
• Processor chips generate heat, requiring cooling solutions like heat sinks and liquid cooling technology.
• Parallel processing uses multiple processors simultaneously to execute a single program or task, and massively parallel processing uses hundreds or thousands of processors.

Data Representation

• Computer circuits represent 0 or 1 electronically by the presence or absence of an electrical charge.
• Eight bits grouped together are called a byte and represent a single character in the computer.
• ASCII (American Standard Code for Information Interchange) is the most widely used coding scheme to represent data.

Memory

• Memory stores instructions waiting for execution, data needed for those instructions, and the results of processing the data.
• Memory consists of data, instructions, and results of processing.
• Each location in memory has an address.
• Memory size is typically measured in Kilobytes (KB or K), Megabytes (MB), Gigabytes (GB), or terabytes (TB).
• The system unit contains two types of memory: RAM (Random Access Memory) and ROM (Read-Only Memory).
• RAM is volatile - data is lost when the computer is turned off.
• ROM is non-volatile - data is retained even when the computer is turned off.
• Memory cache speeds up the computer by storing frequently used instructions and data.
• Flash memory can be electronically erased and rewritten.
• CMOS (Complementary Metal-Oxide Semiconductor) technology is used for flash memory, as it's fast and consumes little power.
• Access time is the duration it takes the processor to read from memory and is measured in nanoseconds.

Expansion Slots and Adapter Cards

• Plug and Play allows the computer to automatically configure adapter cards and peripherals during installation.
• Removable flash memory includes memory cards, USB flash drives, and PC Cards/ExpressCard modules.

Ports and Connectors

• A USB port allows connecting up to 127 peripherals with a single connector.
• Multiple peripherals can be attached to a single USB port using a USB hub.
• A Bluetooth wireless port adapter converts a USB port into a Bluetooth port.
• IrDA (Infrared Data Association) ports allow communication between devices using infrared light.

Storage

• Storage capacity is the number of bytes a storage medium can hold.
• A storage device is computer hardware that records and retrieves items to and from storage media.
• A hard disk contains one or more inflexible, circular platters that use magnetic particles to store data, instructions, and information.
• Hard disks store data using longitudinal or perpendicular recording.
• Hard disks can be internal or external.
• Flash memory storage devices are solid-state, meaning there are no moving parts.
• USB flash drives plug into a USB port on a computer or mobile device.
• Cloud storage is an internet service that provides storage to computer users.
• Optical discs are flat, round, portable discs made of metal, plastic, and lacquer, written and read by a laser.
• Optical discs commonly store items in a single track spiraling from the center to the edge.
• Tracks are divided into evenly sized sectors.
• Optical discs can be read-only or rewritable.
• Tape is a magnetically coated ribbon of plastic capable of storing large amounts of data and information.
• A tape drive reads and writes data and information on a tape.
• Magnetic stripe cards contain magnetic strips that store information.
• Smart cards store data on a thin microprocessor embedded in the card.
• Microfilm and microfiche store microscopic images of documents on a roll or sheet film.
• Enterprise storage stores huge volumes of data and information for large businesses, using special hardware for heavy use, availability, and efficiency.