Apple II User Manual

                       subroutine has been patched in

                   7.  Calls to MID$, LEFT$, RIGHT$, WAIT, PEEK, POKE,

                       TAB, SPC or ON...GOTO with an improper argument.

    ID         Illegal Direct.  You cannot use an INPUT, DEF or GET statement as

               a direct command.

    LS         Long String.  Attempt was made by use of the concantenation operator

               to create a string more than 255 characters long.

    NF         NEXT without FOR.  The variable in a NEXT statement corresponds

               to no previously executed FOR statement.

    OD         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.

    OM         Out of Memory.  Program too large, too many variables, too many

               FOR loops, too many GOSUB's, too complicated an expression, or

               any combination of the above.  (see Appendix B)

    OV         Overflow.  The result of a calculation was too large to be represented

               in BASIC's number format.  If an underflow (too small result) occurs,

               zero is given as the result and execution continues without any error

               message being printed.

    RG         RETURN without GOSUB.  A RETURN statement was encountered

               without a previous GOSUB statement being executed,

    SN         Syntax error.  Missing parenthesis in an expression, illegal character in

               a line, incorrect punctuation, etc.

    ST         String Temporaries.  A string expression was too complex.  Break it

               into two or more shorter expressions.

    TM         Type Mismatch.  The left side of an assignment statement was a

               numeric variable and the right side was a string, or vice versa; or, a

               function which expected a string argument was given a numeric

               one or vice versa.

    UF         Undefined Function.  Reference was made to a user function which

               has never been defined.

    US         Undefined Statement.  An attempt was made to GOTO, GOSUB or

               THEN to a statement which does not exist.

    /0         Division by Zero

B  SPACE HINTS

In order to make your program smaller and save space, the following hints may be useful.

    1.  Use multiple statements per line.  There is a five-byte of overhead associated with each

        line in the program.  Two of these five bytes contain the line number of the line in binary.

        This means that no matter how many digits you have in your line number (minimum line

        number is 0, maximum is 63999), it takes the same number of bytes.  Putting as many

        statements as possible on a line will cut down on the number of bytes used by your

        program.

    2.  Delete all unnecessary spaces from your program.  For instance:

            10 PRINT X, Y, Z

        uses three more bytes than

            10 PRINTX,Y,Z

        Note:  All spaces between the line number and the first non-blank character are ignored.