131 Of course you can have (for example) double height, flashing red letters on a white background 141 Double height 157 New background 129 Red alphanumeric 136 Flashing 10 MODE 7 20 PRINT CHR$(141);CHR$(157);CHR$(129);CHR$(136); "THE LOT" 30 PRINT CHR$(141);CHR$(157);CHR$(129);CHR$(136); "THE LOT" Double height is turned off with control code 140 . As you can see, it can be very tedious typing in CHR$(129) every time you want a Teletext control code. To make things easier it is possible to use the red user defined function keys in combination with the SHIFT key to generate these special codes. While pressing SHIFT the function keys normally produce the codes shown in the following table.
As you will see f0 is set to produce code 128 and the other keys produce higher numbers. 128 is said to be the ‘base address’ for the keys. The base address can be altered with *FX 226 if you wish. See chapter 43 for more details. Once you have a Teletext control code on the screen you can use the editing keys (eg COPY ) to copy it into another string. This can be very useful. f0 f1 f2 f3 f4 f5 f6 f7 f8 f9 128 129 130 131 132 133 134 135 136 137 No effect Alphanumeric Alphanumeric Alphanumeric Alphanumeric Alphanumeric Alphanumeric Alphanumeric Alphanumeric Alphanumeric red green yellow blue magenta cyan white flash on flash off