This presentation is about Computer Systems and its ComponentsPresentation Transcript
Computer Systems and Operating System Chapter 2 2.1.1 Computer System Components
The Computer System By: Alice A. Antwi
Central Processing Unit
The Central processing unit (CPU) is the brain of
the computer, it’s uses are:
To control peripherals
Process tasks like dividing, subtracting etc.
The C.P.U. consists of
- an arithmetic and logic unit (ALU)
- a control unit
- an immediate access (otherwise known as memory unit)
ALU Control Unit Immediate access (memory unit) (memory unit) Output Input The Central Processing Unit Input goes into the C.P.U. and comes out as output. The information has gone through the immediate access, ALU, and the control unit.
Job of the A.L.U .
The ALU does calculations and comparisons and performs processing operations.
It monitors all operations of the computer system such as requesting data from the keyboard.
It makes sure that the computer does it’s job according to the instructions given.
In order to make sure that all operations are performed well, the C.P.U. uses the help of a clock which ticks millions of times every second. A tick of the clock tells the C.P.U. to start a new set of activities, the next tick will start another set of activities.
The speed of a computer .
The speed of a computer is measured in hertz (HZ). One hertz means one tick per second.
One kilohertz (KHz) means 1000 ticks per second.
One megahertz means one million ticks per second.
Some time ago, computers did not have much speed, but some modern computers have speed of 1000 MHz that is a 1000 million of set of activities per second!
To play videos, we need such speed.
A computer handles information in binary form. The binary number system only consists of two digits, 0 and 1.
A bi nary digi t is mostly known as a bit.
A bit is the smallest piece of information a computer can handle. It takes either of the two values, 0 or 1 .
There are two types of computer storage, main memory and permanent storage.
Main memory is the working space of the computer while permanent storage saves your work even if your computer turns off
The main memory takes data and instructions from the permanent storage for processing in the C.P.U.
It is divided into two main parts, namely Random Access Memory and Read Only Memory. Simply, they can be called RAM and ROM.
RAM and ROM come in chips.
Random Access Memory
RAM stores information temporarily. The information can be changed just like writing and drawing on a chalkboard. If the computer is switched off, and the information is not saved, it would be lost.
RAM memory comes in the form of a memory strip or board with a number of microchips built on it.
Read Only Memory
ROM stores information permanently. The information can be accessed by the computer but cannot be changed. Generally, every computer has at least one ROM chip.
If you store information on your computer and turn it off, you lose everything because it is stored in RAM.
To avoid losing your work, you can transfer it to a permanent storage. This can be also called secondary storage.
Permanent/ Secondary Storage
A permanent/ secondary storage can be a floppy disk, hard disk, tape, or a CD. You can change the information stored in it. When you switch the computer off, the information is still there. This is just like your normal audio cassette. You can erase an old song and record a new one.
Floppy disks are most commonly used. It may be very cheap, but its value increases when you store data and programs into it, so you should handle the disk carefully.
Avoid exchanging floppy disks with your friends, as they might be infected with a virus.