The words in line 20 are in reverse printing because that effect was turned on with CHR$(18), but the next line is standard printing because reverse printing stays on for only one line unless it is turned on again. The first word of the last print line is in reverse printing, but the rest is in standard printing because reverse is turned off by CHR$(146). Uppercase I Graphic I Lowercase modes As you know, the screen of your Commodore computer has two modes for displaying letters of the alphabet and graphics characters. They are the uppercase/ graphic mode and the upper/lowercase mode.
In the uppercase/graphic mode (also called the cursor up mode), all letters are uppercase (capitalized) and many graphics characters are available. In the upper I lowercase mode (also called the cursor down mode), letters can be either upper or lowercase, but fewer graphics char- acters are available. To change from uppercase I graphic to upper /lowercase on the screen, you press the SHIFT key and the COMMODORE key at the same time. This command affects only the screen. If you do not give the printer any special instructions, it always prints in the uppercase/ graphic mode. Therefore, all the examples so far in this chapter have been printed in the uppercase I graphic mode.
Before you type any programs that use the upper I lowercase mode, change the screen display to that mode by pressing the COMMODORE key and the SHIFT key at the same time. That way the letters will appear on your screen in the same mode that they are printed on paper. No matter whether you print in the uppercase I graphic mode or the upper/lowercase mode, always have your screen display in the same mode that you plan to print to avoid confusion. If your screen is in the upper/ lowercase mode and your printing is in the uppercase I graphic mode, you will get graphics characters when you want uppercase letters. There are two ways to tell the MPS 1000 to use the upper I lowercase mode:
• Using an extra number (called a secondary address) when you open a file • Using the code CHR$(17). 40