16 Try typing in the following and check that they work – in other words see that they produce the expected answers. PRINT 4 + 8 PRINT 18 - 2 * 4 PRINT 131/4 PRINT SQR(2) The last one will print the square root of 2 which is 1.41421356. Then try MODE 5 which will make the computer clear the screen and get it ready to draw lines as well as text. In this mode COLOUR 129 will select a red background, and CLS will clear the screen to the background colour. In each case you have given the computer a command and it has obeyed it immediately. Working like this is called ‘working in command mode’. While in this mode you might like to learn how to use the bright red user defined function keys .
Each of these keys can be used to store a word or several words. For example they could be programmed so that each one selects a different colour. Try this: *KEY 2 COLOUR 2 |M The | shown above is produced by a special key. On the keyboard this key is the third key from the right on the row below the red keys. In MODE 7 this key produces R on the screen. Once you have typed that in then every time you press the key marked f2 , the computer will change to COLOUR 2 which gives yellow lettering. In a similar way you could program some of the other keys like this: *KEY 0 COLOUR 0 |M *KEY 1 COLOUR 1 |M *KEY 3 COLOUR 3 |M Note the exact position of spaces when you type in a command.