Appendix Error Message What caused the error and how to fix it *Subscripts must be equal to or greater than 0, and less than or equal to 65535. ** Be sure the argument is within the range of the function being used. 1. Error messages When an error occurs. PET returns to Command level and displays READY on its TV screen. Variable values and the program text remain intact, but the program cannot he continued using the CONT command. GOSUB and all FOR ... NEXT context is lost, insofar as the current run is concerned. NEXT WITHOUT FOR The variable in a NEXT statement corres- ponds to no previously executed FOR statement. The FOR part of a FOR ...
NEXT loop must be inserted or the offending NEXT part of the loop must he deleted. Be sure the index variables are the sunk at both ends of the loop. Example: FOR I = I TO 10 NEXT I When an error occurs in a program statement, the error message dis- play will indicate the line number in which the error occurred. When the error occurs in a direct, or command level, statement, no Tine number is displayed with the error message. OUT OF DATA A READ statement was executed but all of the DATA statements in the program have already been read. The program tried to read too much data or insufficient data was included in the program.
Error Message What caused the error and how to fix it CAN'T CONTINUE Attempt to continue a program when none exists. an error occurred, after a new line was typed into the program, or a correction was made to an existing line. Use the RESTORE: statement to restore the data so PET can read it again, or restrict the number of READs to the correct number of DATA elements, or add more DATA elements, or use a flag at end of data list check for it before reading. Correct the error, then use a directed GOTO to get back into the program, or type RUN and start over. OVERFLOW The result of a calculation was too large to he repre sented in BASIC's number format.
(If an underflow occurs, zero is given as the result and execution continues without any error message being printed.) DIVISION BY ZERO Dividing by zero is an error. Check the expression used for the denominator in the offending arithmetic statement. then correct it so it can never he evaluated as 0 . ILLEGAL DIRECT Use of an INPUT, GET, or DEF statement as a direct command. You requested a number greater than even PET can remember. Try asking for a smaller number. The largest possible number is 1. 70141 183E+38. Change the order of your calculations. Avoid using these statements as direct commands. ILLEGAL QUANTITY The parameter passed to a math or string function was out of range.
"ILLEGAL QUANTITY" errors can occur due to: REDIMENSIONED ARRAY After a matrix was dimensioned, another dimension statement for the same matrix was encountered. This error often occurs if a matrix has been given the default dimension 10 because a statement like A( I)=3 is encountered and then later in the program, a l)IM A( 100) is found. a. a negative matrix subscript, such as LET A (-I ) = 0* b. an unreasonably large matrix subscript: X=A(65536)* c. LOG-negative or zero argument, as LOG(-X)** d. SQR- negative argument, as SQR(-4) e. At B if A is a negative value and B is not an integer.
(It works if a constant is used instead of a variable, i.e., -4t B, because exponentiation is performed before unary minus.) f. A call to USR before the address of the machine language subroutine has been patched in. 37 www.commodore.ca Free for personal use but you must have written permission to reproduce 36