The system unit is a case that contains electronic components of the computer used to process data.
The inside of the system unit on a destop includes:
1.Drive bay
2.Power supply
3.Sound card
4.Video card (Graphic card)
5.Processor
6.Memory(Ram)
The processor , also called the central processing unit(CPU), interprets and carries out the basic insturctions that operate a computer. - Contain a control unit and an arithmetic logic unit (ALU) ,Multi , Dual and Quad core processor.
The control unit is the component of the processor that directs and coordinates most the operations in the computer.
The arithmetic logic unit (ALU) performs arithmetic , comparison , and other operations.
The processor contain registers , that temporarily hold data and instructions.
The system clock controls the timing of all computer operations. Clock speed is measured in gigahertz(*GHZ)
A processor chip generate heat that could cause the chip to burn up so it will require additional cooling component like Heat sinks or Liquid cooling technology.
Analog signals are continuous and vary in strength and quality.
Digital signals are in one of two states: On or Off.
The binary system use two unique digits ( 0 and 1) Bits and bytes.
ASCII is the most widely used coding scheme to represent data.
Memory
Memory consists of electronic components that store instructions waiting to be executed by the processor , data needed by those instructions , and the results of processing the data .
Stores three basic categories of items:
1. The operating system and other system software
2. Application programs
3. Data being processed and the resulting information
Memory size is measured in kilobytes (KB or K) , Megabytes (MB) , gigabytes (GB) or terabytes (TB)
The system unit contains two types of memory:
1. Volatile memory - Loses its contents when power is turned off, example include RAM.
2.Non-volatile memory - Doesn't lose contents when power is removed., example include ROM, FLASH MEMORY AND CMOS.
Three basic types of RAM chips exist: Dynamic RAM , Static RAM, Magnetoresistive RAM
RAM chips usually reside on a memory module and are inserted into memory slots.
The amount of RAM necessary in a computer often depends on the types of software you plan to use.
Memory cache speeds the processes of the computer becasue it stores frequently used instructions and data.
Read-only memory (ROM) refers to memory chips storing permanent data and instructions. Firmware.
A PROM (programmable read-only memory) chip is a balnk ROM chip that can be written to permanently.
EEPROM can be erased.
Flash memory can be erased electronically and rewritten. - CMOS technology provides high speeds and consumes little power.
Access time is the amount of time it takes the processor to read from memory . -measure in nanoseconds.
Expansion Slots and Adapter Cards
An expansion slot is a socket on the motherboard that can hold an adapter card
An adapter card enhances functions of a coimponent of the system unit and / or provide connections to peripherals . -Sound card and video card .
With PLUG AND PLAY, the computer automatically can be easily configure adapter cards and other peripherals as you install them.
Removable flash memory includes: Memory cards, USB flash drives, PC cards
Ports and Connectors
A port is the point at which peripheral attaches to or communicates with a system unit.
A connector joins a cable to a port.
A USB port can connect up to 127 different peripherals together with a single connector.
Other types of ports include: Firewire port , Bluetooth port , eSata port and MORE .
Buses
A bus allows the various devices both inside and attached to the system unit to communicate with each other - Data bus , Address bus
Word size is the number of bits the processor can interpret and execute at a given time.
BAYS
A bay is an opening inside the system unit which you can install additional equipment\
Power supply
The power supply converts the wall outlet AC power into DC power.
Some external peripherals have an AC ADAPTER , which is an external power supply.
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