The system unit, also known as a "tower" or "chassis," is the main part of a desktop computer. It includes the motherboard, CPU, RAM, and other components. The system unit also includes the case that houses the internal components of the computer. The term "system unit" is often used to differentiate between the computer and peripheral devices, such as the monitor, keyboard, and mouse. For example, if a repair shop asks you to bring in your computer, it may be unclear whether you need to bring your monitor and peripheral devices as well. If you are told to just bring your system unit, it is clear you only need to bring the computer itself. Some modern computers, such as the iMac, combine the system unit and monitor into a single device. In this case, the monitor is part of the system unit. While laptops also have built-in displays, they are not called system units, since the term only refers to desktop computers.
Motherboard:-The motherboard is the main circuit board of micro computer. it is also know as main board or system board.
CPU:-The CPU is the central electronic chip that determines the processing power of the computer.
Memory:-Memory is the part of computer that temporarily store application documents, and system operating information.
Bus:-A bus is an electronic line that allows is and OS to move from on place to another.
Expansion Slot:-expansion slot appear on the motherboard. They are sockets into which adapters are connected
Ports and connectors: -A port is connector located on the motherboard or on a separate.
Bays:-a bay is a space inside the computer case where a hard drive, floppy drive or CD- ROM drive sits.
Power supply:-A power supply changes normal house hold electricity into electricity that a computer can sue
Sound components:- A sound card lets a computer play and record high quality sound.
Central Processing Unit
Today, all CPU are microprocessors
1. A microprocessor is a complete on a silicon chip
2. A microprocessor does all of the functions of a computer
Store data and instructions waiting be use Follows changeable instructions Does input, processing. And output CPU's have there basic parts
1. the arithmetic logic unit (AUL)
Does all of the mathematics in computer. Does all of the logic compression of values. Some common logic compression symbols.
= equal to <less than >grater than <=less than or equal to >= greater than or equal to <>not equal
2. the control unit
Directs flow of information into the CPU and/or storage.
Control which instruction the CPU will do next.
3. register
Used to story data and instructions inside the processor. Size of the register can affect the speed and performance of the processor
Speed of CPU's
The sped of CPU's measured in hertz’s.
A hertz is on cycle per second. Need to measure time determine cycles per second. All computers have a clock built into them of timing the cycles. The clock is usually located in a small metal box on the Motherboard. Today, many CPU's can complete over six (6) instructions per second.
Speed or modern CPU’s
Most computers have a CPU than do more than 400 MHZ. MHZ stands for megahertz’s. A MHZ is 1,000,000 cycles per second. Computer will soon be at speeds over gigahertz 1,0000,000,000 hertz
Memory:-
Primary memory can be used directly by the CPU
Consists of silicone chips, usually either VLS VLSI technology use to Create chips. Tow forms primary memory. Read only memory. (ROM) Random access memory (RAM) Primary memory is also called primary storage.
Read Only memory (ROM)
Rom:-
Store instructions that are used by the CPU
Tells the CPU to be kind of computer is it, for example a windows, Macintosh, or play station computer.
Tells the CPU how to work with the different parts of the computer.
ROM also hold program that are directly accessed by the CPU One Such program in the self-test when the computer is first turned on. The self-test to seem if all the parts on the main circuit board (motherboard) are working correctly.
The instruction ROM can not usually be changed. The instructions are built into the electronic circuit of the chip. These instructions in ROM are called firmware. To change the intrusions in Rom you need to usually change the chips or do Some other special process that normally not available to an average user. The instruction in ROM is nonvolatile. They stay in ROM even when the computer is turned off.
Access to information is random access. Random access means that any piece of information first. It is lot like the tracks on music CD. You can access any track any time and in any order. The other kind of access is sequential access. You must access the information in the ordered that they are located. This is a lot like a music tape. You must play the songs in order; you have to fast forward past songs to get the one you want
Random Access Memory (RAM)
Store data and instruction that are used by the CPU to perform some task. These instructions are usually loaded into RAM from secondary storage device. RAM is also used to store instructions that tell the CPU how to work with its parts. These instructions are usually called drivers. The intrusions in RAM constantly changing. Depending on the needs of the CPU. The instruction in RAM is volatile. When the computer turned off the information in RAM disappears. The information in RAM needs to be saved to secondary storage before the computer turned off. Access to information is random access.
How a store computer information The computer store information as a string of zero (0) and ones (1) The standard string length is eight 0’s or 1’s in an arrow The standard length is called byte A byte equals one chartered A character is a letter, number or symbol – it is about any thing that can be type on keyboard. There is 1156 standard character use by almost all computers. Information size measurement
Kilo byte (KB) One kilobyte equal about 1024 bytes 1 KB is about 140 words, about a half page typed double-spaced text words only)
Megabyte (MB) One megabyte equals about 1000 KB One megabyte equals about 1,000,000 bytes One megabyte equal about 500 text pages or one large book
Gigabyte (GB) One gigabyte equals about 1000 MB One gigabyte equals about 1,000,000 KB One gigabyte equals about 1,000,000,000 bytes One gigabytes equals over 1, 00 books of text
Hard drive The hard drive is the primary devices that a computer uses store information. The hard drive stores Programs, data files, save and organizes files. The hard drive is located inside the computer case. The hard drive magnetically stores data on stack of rotating disk called platters.
HDD
Floppy drive
The floppy drive store and retrieves information on a floppy disk.
CD ROM Drive
CD- ROM is a device that reads information stored in a compact disk. CD- ROM stand for compact disc read only memory. One CD is equal to the space in over 40 floppy
Removable Hard Disk
A zip disk is a removable disk that holds a large amount of information. A zip disk can be used achieve, protect transfer large amount of data.
Motherboard
Motherboard Back Panel
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