RUN’s Checksum (Bob Kodadek)

Title – RUN’s Checksum Program
System – Commodore 64
Author – Bob Kodadek
Publication – RUN, January 1988 onwards
Page Scans – 1
Preserved by – eboy71
Recommended Emulator – VICE

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Download ROM

Loading the Game –

• Mount the disk image (RUNs Checksum.d64) in your emulator. In VICE, this is done by selecting File → Attach Disk Image
• Load the app by typing LOAD”RUNS CHECKSUM”,8,1
• Once loaded, type RUN to start
• After it has been ran, toggle Checksum on or off by typing SYS 49152

Details:

• RUN’s Checksum Program is a small program that resides in memory while you are typing your program. After typing each line, a checksum is displayed in the top left corner of the screen. If it corresponds to the checksum printed in the issue, your line is correct.
• This is the second version of RUN’s proofreading and it was introduced in January, 1988. The original version was called Perfect Typist, which worked for programs published in RUN from September 1985 to December 1987.

Article Text

RUN’S ORIGINAL PERFECT TYPIST programs have been valuable aids, but they’re not as perfect as one would like. To improve the situation, we’re introducing a new entry program, RUN’S Checksum which all programs listed in RUN will use beginning with this issue. The most noticeable difference between our new program and the Perfect Typist is that RUN’S Checksum serves for both the C-64 and the C-128,

A less obvious difference is that RUNs Checksum uses an algorithm that ensures that every byte of data entered has a unique value, depending on its position in the line. As with Perfect Typist, all you need to do is compare the checksum that appears with the value presented as REM*### at the end of each line in the program listing.

How To Use RUN’S Checksum
Type in RUNs Checksum in either 64 or 128 mode and save it to disk before running. When you’re ready to type in a program from RUN, first load and run RUNs Checksum. It will automatically detect which computer it’s running on, make the necessary adjustments and display either the 64 or 1 28 version on the screen. At this point, you’ll also see a SYS number that displays the starting address for activating die checksum. Always use this SYS number to toggle the Checksum on and off.

Pressing the run-stop and restore keys will not disable this utility. In order to turn off RUN’S Checksum, enter the SYS command and press the return key. Entering this SYS command again will re-activate the checksum. Be certain to disable RUNs Checksum before attempting to run another program from Basic.

Similarities and Differences
RUN’S Checksum retains the features of Perfect Typist and functions in exactly the same way, except that it produces different checksum numbers. Therefore, you cannot use RUNs Checksum to type in listings from any RUN issues prior to this one. On the other hand, all listings starting with the January 1988 issue cannot be been valuable aids, but they’re not as perfect as one would like. To improve the situation, we’re introducing a new entry program, RUN’S Checksum which all programs listed in RUN will use beginning with this issue. The most noticeable difference between our new program and the Perfect Typist is that RUN’S Checksum serves for both the C-64 and the C-128,

A less obvious difference is that RUNs Checksum uses an algorithm that ensures that every byte of data entered has a unique value, depending on its position in the line. As with Perfect Typist, all you need to do is compare the checksum that appears with the value presented as REM*### at the end of each line in the program listing.

How To Use RUN’S Checksum
Type in RUNs Checksum in either 64 or 128 mode and save it to disk before running. When you’re ready to type in a program from RUN, first load and run RUNs Checksum. It will automatically detect which computer it’s running on, make the necessary adjustments and display either the 64 or 1 28 version on the screen. At this point, you’ll also see a SYS number that displays the starting address for activating die checksum. Always use this SYS number to toggle the Checksum on and off.

Pressing the run-stop and restore keys will not disable this utility. In order to turn off RUN’S Checksum, enter the SYS command and press the return key. Entering this SYS command again will re-activate the checksum. Be certain to disable RUNs Checksum before attempting to run another program from Basic.

Similarities and Differences
RUN’S Checksum retains the features of Perfect Typist and functions in exactly the same way, except that it produces different checksum numbers. Therefore, you cannot use RUNs Checksum to type in listings from any RUN issues prior to this one. On the other hand, all listings starting with the January 1988 issue cannot be entered with either the 64 or the 128 Perfect Typist.

Keep the following in mind when you’re entering listings: Basic keywords can be abbreviated; spaces affect the checksum only if they appear within quotes; and the order of characters will affect the checksum value. After entering a Basic line and pressing the return key, a one-, two- or three-digit number from to 255 appears in the left-hand margin directly below the line you entered.

If the number matches the checksum value in the program listing, the line is correct, and you may continue. You enter the next line by typing it in directly over the previous line’s checksum value. If the number that appears doesn’t match the listing’s checksum value, then proofread the line, comparing it with the magazine listing. Then move the cursor back up to the line and make your corrections. After you press return, the correct checksum value should appear. Continue entering the listing in this manner until all the program lines have been entered, and then deactivate RUNs Checksum, using the SYS number. Save the finished program.

Limitations
While our new checksum utility can find any entry errors, it won’t detect an omitted line. If all the checksums match and the program still won’t run, look carefully to see that you’ve entered every line from the listing. Another problem that may occur is a conflict with another resident program, such as the DOS Wedge.

Also, before you attempt to run a new program for the first time, it’s good practice to remove any resident programs and cartridges. This can be done by turning the computer off and then on again or by performing a system reset. On the 128, press the reset button on the right-hand side of the computer, 64 users can enter SYS 64738 and press the return key. But, before doing this, make sure you’ve saved a copy of the new program.

Editor’s Note:

• The author, Bob Kodadek, published many programs in RUN.