Computer System
Senior 1 · ICT
Computer System
Lesson 1 of 5
16 min
Let's begin
When your parent sends 5,000 Frw by mobile money, a lot happens in a few seconds. They type the number and amount. The system checks the balance and moves the money. A message confirms the payment. A record is kept so that the payment can be checked later. Those four steps, input, processing, output and storage, are what every computer does, from a phone to the biggest supercomputer.
A computer is an electronic machine that accepts data, processes it by following a set of instructions called a program, produces results, and stores data for later use.
| Function | Meaning | Example parts |
|---|---|---|
| Input | Putting data and instructions into the computer. | Keyboard, mouse, microphone, scanner, touchscreen |
| Processing | Working on the data: calculating, comparing, sorting. This is done by the processor (CPU). | CPU |
| Output | Giving the results to the user. | Monitor, printer, speakers, projector |
| Storage | Keeping data and programs so that they can be used again. | Hard disk, SSD, flash drive, memory card |
Together these make the input–process–output–storage cycle, often shortened to IPOS.
A computer system is everything needed to make a computer useful:
Hardware without software cannot do anything, and software needs hardware to run on.
Computers are fast (billions of simple operations per second), accurate, never get tired, and can store huge amounts of data. But a computer cannot think for itself: it only follows instructions. If you give it wrong data, it gives wrong results. Programmers call this GIGO: garbage in, garbage out. If a teacher types 9 instead of 90, the average will be wrong, however fast the computer is.
Tip
IPOS: In, Process, Out, Store. For any task, ask: what goes in, what does the CPU do with it, what comes out, and what is kept?
Name the function: (a) scanning a photo; (b) printing a certificate; (c) saving a file to a flash drive; (d) working out the total of a bill.
Solution: (a) input; (b) output; (c) storage; (d) processing.
Describe the IPOS steps when you withdraw cash at an ATM.
Solution: Input: you insert your card and type your PIN and the amount. Processing: the bank's computer checks the PIN and your balance and subtracts the amount. Output: the machine gives out cash and a receipt. Storage: the bank records the withdrawal in your account history.
Say whether each is hardware or software: a mouse, a web browser, a printer, Windows.
Solution: Hardware: mouse, printer. Software: web browser, Windows.
A calculator program shows the total of 40 + 30 + 20 as 900. The program works perfectly. Explain.
Solution: Garbage in, garbage out. The user probably typed a wrong number, for example 850 instead of 40 (850 + 30 + 20 = 900). The computer processed the wrong input correctly.
Remember
Sources and credits
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.
