in the example programs that follow, all references to a particular mode apply

equally well to its lower-numbered counterpart.

Modes 128, 129, 130, 132 and 133 are known as graphics modes because they

allow the use of both text and graphics. Modes 131 and 134 are text-only

modes. Mode 135 allows the use of graphics, but the commands involved are

very different and so are dealt with in a separate section beginning on page (361.

In each of the graphics modes, points on the screen are given coordinates so

that their position can be identified.

The point A in the figure has coordinates 640 across and 512 up, roughly the

middle of the screen. The point B is at position 100,800 and C is at 1000,20.

Type in and run this program:

10 MODE 128

20 MOVE 1900100

30 DRAW 800,100

40 DRAW 800,900

50 DRAW 100,100

Line 10 changes to a graphics mode, and as a result the invisible graphics

cursor is automatically positioned at point 0,0 -- the bottom left comer of the

graphics screen.

Line 20 causes the computer to move to 100,100 without drawing a line.

The DRAW command draws a line from the last point visited (which was

100,100) to 800,100. The remaining DRAW commands produce a series of

joined lines making a triangle.

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