The same text must be printed on two successive lines beginning with

CHR$(141), otherwise only the top half of the letters is displayed.

Changing the background colour uses two codes:

PRINT CHR$(131);CHR$(157)

The first code is for yellow text. CHR$(l57) tells the computer to use the

previous control code as the background colour. The net effect of the two codes

is to give yellow text on a yellow background, as you can see if you type:

PRINT CHR$(131);CHR$(157);"Hello"

This is obviously not very useful, as the text is unreadable. To print text visibly

on a coloured background requires three control codes, two codes to change the

background colour and a third to change the colour of the text:

PRINT CHR$(131);CHR$(157);CHR$(132);"Blue on yellow"

The first two codes set the yellow background and CHR$(l32) is the code for

blue text.

All of these codes can be combined and incorporated into strings. If you intend

to use a particular set of codes many times within a program it is useful to set

up a single string containing those codes:

10 MODE 135

20 ryflash$=CHR$(131)+CHR$(157)+CHR$(129)+CHR$(136)

30 PRINT ''ryflash$; "A demonstration"

40 PRINT "of normal printing"; ryflash$; "and in colour"

Teletext graphics

All graphics in mode 135 are produced as the result of printing characters. If

any line contains a graphics control code, any characters other than upper-case

letters that appear after it on the same line are printed as graphics shapes.

Each letter corresponds to a particular shape which is based on a two by three

grid, for example:

C 63