Computing PPE Revision

Computing PPE Revision

1. What is sequence, selection and iteration?

   • Sequence is a set of instructions in an order.
   • Selection is instructions which which will run depending on a condition being true or false.
   • Iteration is instructions which can repeat (either a set number of times or depending on a condition being true or false).

2. Memory

   • The difference between RAM and ROM is that RAM is volatile and ROM is non-volatile. RAM stores all the programs that is being used and ROM stores the info to boot up the PC.
   • A computer system need secondary storage in order to store operating systems, programs and files.

3. Ethical and cultural issues

   • A stakeholder is anyone with an interest in a business. Stakeholders are individuals, groups or organisations that are affected by the activity of the business.
   • A cultural issue is an issue which affects a particular group of people. A “culture” can be described as the values, beliefs and social behaviour of particular people or a society.

4. Producing Robust programs

   • Validation checks that an input meets the expected criteria. It cannot check for accuracy, only that the input is sensible.
   • The main ways of validating data are List check, Presence check, Format check, Length check, List check, Type check

5. Binary Images

   • Metadata stores information about the image file. This is so that the computer can understand how to recreate the image on the screen.
   • Binary is use to represent using pixels by 1. A bitmap image is made up of pixels. 2. Each pixel is given the binary code of the colour it needs to display. 3. Every available colour is given its own unique binary code. 4. Metadata is stored about the image (such as height, width, colour depth, resolution and file format)