47 We’ll consider what happens when the first number is not zero later on (chapter 29). As with the text colours, you can change both foreground and background colours. However, before that can be illustrated it will be easier to set up two windows on the screen – one for text and one for graphics so that you are sure which is which. We will then return to the GCOL statement. Windows At the moment the whole screen can be used for text and the whole screen can be used for graphics. In some modes (eg MODE 5 ) we can restrict each to a specific window – or section of the screen. In modes without graphics ( MODE 3 , 6 and 7 ) only text windows can be used.
Imagine we want to create two windows as shown below – on the left a graphics window, on the right a text window. Suppose that the text window stretches from the top of the screen right to the bottom but the graphics window stops short of the bottom: Imagine a graphics window which has its edges a, b, c and d ‘graphics units’ away from the bottom left hand corner of the screen (which is always the starting point for graphics). Making a graphics window