C:CHECK

16K Cassette
 

CHECK Program by Istvan Mohos
Cassette version by Tom Hudson 

Well, cassette fans, here it is! a checksum program for use with your ATARI 410 program recorder. A.N.A.L.O.G. has been using a program called D:CHECK since issue #8, but it could only be used by disk drive owners. This program, based on Istvan Mohos’ program "D:CHECK," will allow cassette-bound readers to verify that programs typed in from A.N.A.L.O.G. were entered correctly.

The Program

When D:CHECK was submitted to A.N.A.L.O.G. for publication, it was intended to be used only with the ATARI 810 disk drive. It could not be used with cassette because it required three separate “passes” through the BASIC program being checked. This is fine when using a disk drive, which is a “random access” device. A disk drive can read a file of stored information any number of times without the user even noticing. A program recorder, on the other hand, is a “sequential” device. If a file must be read several times, the user must rewind the tape to the beginning of the file each time it is needed. This is, to say the least, a cumbersome operation.

In order to adapt D:CHECK for cassette use, a prime consideration was to make the check process a one-pass operation. C:CHECK will read through a program which has been LISTed to cassette one time and produce the checksum data on either the screen or a printer.

To make life easier for the A.N.A.L.O.G. staff, C:CHECK will produce the same checksum data as D:CHECK, eliminating the need for separate checksum tables.

Type the C:CHECK program into your computer and LIST it to tape. Check data has been provided so that you can use C:CHECK to check itself. Follow the instructions below.

Using C:Check

When entering programs from A.N.A.L.O.G., you can use C:CHECK to make sure you typed them in without mistakes. The procedure is as follows:

  1. After the program is typed in, LIST it to tape by typing LIST “C”.
  2. LOAD and RUN C:CHECK.
  3. C:CHECK will ask if you want the output to go to the screen or to a printer. Type “S” for screen or "P" for printer and press RETURN.
  4. Enter the issue number in which the program to be checked appeared, and press RETURN.
  5. Position the tape to the beginning of the program that is to be checked and press PLAY on the program recorder. Press RETURN.
  6. C:CHECK will begin reading the program from tape and generate a checksum table. This table should match the C:CHECK/D:CHECK data listed after the program in the magazine. Each line of the checksum table is a DATA statement representing 15 lines of the program being checked, plus a total of the 15 lines. The line number of each DATA statement is the number of the first line in the group of 15 lines. For example, in the following check data line:

100 DATA 12,3,200,126,60,45,344,455,452,54,889,344,10,1,56,3051

The line number 100 tells that the first line in this group is 100. The value 12 represents the checksum of line 100, 3 is the checksum of the first line after line 100,200 is the checksum of the second line after 100, etc. 3051 is the total of the 15 lines in the group. If the value 889 does not match the magazine’s corresponding value, the tenth line after line 100 was typed incorrectly.Note all such errors. When C:CHECK ends, type NEW, ENTER your program from tape and correct the lines that are in error (if any). When these are corrected, you have a perfect, debugged copy of the program!

That’s all there is to it! C:CHECK should make finding those bothersome typos much easier, and allow you to enjoy A.N.A.L.O.G. programs much faster.