Moving The New Proofreader's Checksum

When I use the "Automatic Proofreader" with my Commodore 64, the checksum is displayed too high on my screen to be visible. Is there any way to modify the program so it prints the checksum lower on the screen?

Melvin Baral

The problem you mention is typical of TV sets or monitors that suffer from severe overscan (they can't display all of the picture on the screen). If you can't adjust the picture to include the top screen line, you'll have to modify the program. In this issue, we're introducing the "New Automatic Proofreader" for Commodore computers, which works on the 64, 128, VIC-20, Plus/4, and 16. Though it's designed to print the checksum in the upper-left corner of the screen, the new Proofreader can be made to print it elsewhere. First, follow the instructions in the article for typing and saving the new Proofreader. Then reload it and make the following changes:

• In line 80, change 20570 to 20551.
• In line 110, change 22054 to 22035.
• In line 190, change 19 to 0.

Now resave the program, using a different filename so you can tell it apart from the original version. The modified Proofreader prints the checksum just below the last line entered, rather than at the top of the screen. You can either type the next line number over the checksum, or move the cursor down to the next blank line and then start typing. Since this modification makes the Proofreader less convenient for listing and rechecking a group of existing program lines, you probably won't want to make this change unless it's absolutely necessary.