# 6 Computers as systems

As already mentioned, the functional blocks shown in Figure 5 relate very closely to, even though they are not necessarily identical with, the computer’s physical components. The computer’s physical components are normally known collectively as the hardware. Software is a term often used to refer to a computer program or a collection of computer programs which enable a computer to carry out its tasks. As the course progresses you will find out more about computer hardware and software, including the processor and the programs it runs. Through this you will gain an understanding of what form the data used by the processor and memory must take, and hence understand the role of the input and output subsystems.

## Activity 3

For the PC shown in the advert in Figure 1 (in Section 1), write down how the following items of hardware relate to the functional blocks in Figure 5 (in the previous section). For simplicity, assume that items that provide input functionality relate to input devices, rather than input subsystems, and similarly items that provide output functionality relate to output devices rather than output subsystems.

- keyboard
- display
- 500 GB hard drive
- 6 GB DDR3 RAM
- speakers
- touchpad
- SD reader.

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### Discussion

The keyboard and mouse relate to input devices. The display and speakers relate to output devices.

To decide whether the 500 GB hard drive relates to the secondary memory, to the secondary memory subsystem or to the combination of both you need to make an intelligent guess about what those who wrote the advert meant. In this case they probably meant the combination of the two.

The 6 GB DDR3 RAM relates to main memory.

The SD reader relates to secondary memory.

## Activity 4

The laptop shown in Figure 1 contains a sound card and a network card. What problem arises if you try to relate these two items to the functional blocks of Figure 5?

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### Discussion

The two items can function both as input and as output devices.

The terms input-output device and input-output subsystem are sometimes used where items have both input and output functionality. Hence a sound card is an input-output subsystem.

Finally, just as you are just becoming familiar with all of the terms that have been introduced, a word of caution. When you read books or other literature about computers you may find some of the terms used differently. This is not necessarily a problem, and is common when technical terms become part of everyday language. However, throughout your study of this course you do need to make sure that you use the terms as defined here.

One term not used here that you might come across is computer system itself. Historically some people used the terms ‘computer’ and ‘computer system’ rather differently. The term computer was focused on the processor and computer system referred to the processor and its devices to make it a usable ‘system’. But that is no longer the case, and nowadays the word ‘system’ tends to be omitted. A good example is the use of the term ‘personal computer’, which would several years ago have often been described as a ‘personal computer system’ to cover the combination of a box with the processor and memory, and attached devices usually a screen, keyboard and mouse.

OpenLearn - An introduction to computers and computer systems
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