Chipmunk Basic Reference Manual


 

                            Chipmunk Basic Man Page
     _________________________________________________________________


    BASIC(1)            Chipmunk Basic v3.6.6                   BASIC(1)


        Chipmunk BASIC - 'BASIC' language interpreter


    SYNOPSIS    ( UNIX )

        basic [ filename ]

    DESCRIPTION

        Chipmunk basic is an interpreter for the BASIC programming
	language.
	
	If a filename parameter is given, the named program file is
	loaded into memory and run.   If the filename starts with
	a colon (":") character, then the rest of the string is
	executed as a Basic statement.

        Basic commands and statements can be entered and interpreted
        in immediate mode or executed as program statements when the
        Basic program is run.  A built-in line number based editor
        allows program input from the console keyboard.  See below
        for the commands and statements which the interpreter
        recognizes.

    FLAGS

        none

    COMMANDS
        
        Standard mumbleSoft-like Basic Commands:

        load STRINGEXPR

                Load a program into memory from the named file. The
                program previously in memory is erased.  All files are
                closed and all variables are cleared.  Lines beginning
                with the '#' character will be treated as comments. 
                All other lines in the file must begin with a line
                number.  Duplicate line numbers are not allowed.


        save STRINGEXPR

                Save the current program to the named file.

        new

                Erase the program in memory.  All files are closed and
                all variables are cleared.

        clear

                All  variables are cleared.  All arrays and string
                variables are deallocated.

        run { LINENUM }
        run { STRINGEXPR { , LINENUM } }

                Begin execution of the program at the first line, or at
                the specified line.  All variables are cleared.  If a
                STRINGEXPR is given then the BASIC program with that
                name file is loaded into memory first.  Program lines
                are executed in line number order.

        cont

                CONTinue execution of the program on the next statement
                after the statement on which the program stopped
                execution due to a STOP command or an error.  See BUGS
                section.

        LINENUM { TEXT }

                Enters a program line.  If a program line with
                line number LINENUM exists, then it is replaced.
                If no TEXT is given, the the program line with
                line number LINENUM is deleted.

        list
                List the whole program.
                Line numbers above 999999999 will not list.

        list 1-3
                List lines 1 to 2

        list -2
                List lines up to 1

        list 1
                List line 1

        list 2-
                List lines from 2 on

        merge STRINGEXPR

                Loads a program into memory.  The previous program
                remains in memory; variables are not cleared.  If a
                line exists in both programs, the new merged line
                overwrites the old one.

        renum STRINGEXPR VAL { , VAL { , VAL { , VAL} } }

                Renumber program lines.  By default, the new sequence is
                10,20,30,... The first argument is a new initial line
                number; the second argument is the increment between
                line numbers. The third and fourth arguments, if
                present, specify a limiting range of old line numbers
                to renumber.  RENUM can be used to move non-overlapping
                blocks of code.
         
        edit LINENUM

                Edit a single line. If the exit from the edit is via a
                cntrl-c then the program line is not modified.
                        i       insert till  key
                        x       delete one char
                        A       append to end of line

        del LINENUM [ - LINENUM ]

                Delete a line or specified range of lines. If not found
                then no lines will be deleted.

        exit
        bye
        quit
                Terminates the basic interpreter, ending program
                execution and closing all files.


    STATEMENTS

        { let } VAR = EXPR

                Assign a value to a variable.  

		See the VARIABLES section below for more information
		of variable types available.

		
        end

                Terminates program execution and returns to the command
                prompt.  Not required.

        stop

                Stops the execution of the program and returns to
                the command prompt.  Prints a "Break..." message.

        if EXPR then STATEMENT { : STATEMENT } { { : } else STATEMENT }
        if EXPR then LINENUM
        if ( EXPR ) { then }

                The IF statement.  If the condition is true then the
                STATEMENTS after the THEN are executed and the
                statements after the ELSE are skipped.  If the
                condition is false then the statements after the "else"
                are executed instead.  If the item after "then" is a
                line number then a goto is executed.

		Multi-line block syntax:
		IF (EXPR) { THEN }
		... 
		{ ELSE }
		... 
		ENDIF

                If there are no statements on the same line as
                the IF statement, and the condition is true, then
                statements are executed until a line with an ELSE
                or ENDIF is found.  If an ELSE is found first the
                following statements are skipped until an ENDIF is
                found.  If the condition is false, then statements
                are skipped until and ELSE is found.  IF .. ENDIF
                blocks may be nested.


        for VAR = EXPR to EXPR { step EXPR }

                Beginning of a FOR-NEXT loop.  It takes a starting
                value, a limit and an optional step argument.  If the
                step value is negative, the variable counts down.  The
                body of the loop is not executed if the end condition
                is true initially.

                Example:
                        for i=1 to 10 : print i, : next i
                        rem prints the numbers from 1 through 10

        next { VAR }

                End of a FOR-NEXT loop.  If the termination conditions
                are met then execution falls through to the following
                statement, otherwise execution returns to the statement
                following the FOR statement with the corresponding
                index variable. If there no index variable parameter,
                the innermost FOR loop is used.

        exit for

                Exits the current FOR-NEXT loop.

        while { EXPR }

                Start of a WHILE loop. The loop is repeated until EXPR
                is false. If EXPR is false at loop entry, then the loop
                is not executed . A WHILE loop must be terminated by a
                balancing WEND statement.

        wend { EXPR }

                Terminating statement of a WHILE loop.  If EXPR is true
                then exit the loop.  Only one WEND is allowed for each
                WHILE.  A WHILE-WEND loop without a condition will loop
                forever.

        exit while

                Exits the current WHILE-WEND loop.

        gosub LINENUM

                Transfer command to a line number. Save return address
                so that the program can resume execution at the
                statement after the "gosub" command.  The recursion
                depth is limited only by available memory.

        return

                Returns from the most recently activated subroutine
                call (which must have been called by GOSUB).

        goto LINENUM

                This statement will transfer control to the line number
                specified.  If the program is not running, then this
                command will begin execution at the specified line
                without clearing the variables.  An "Undefined line"
                error will occur if LINENUM doesn't exist in the
                program.

        on EXPR   goto  LINENUM { , LINENUM ... }
        on EXPR   gosub LINENUM { , LINENUM ... }
                This command will execute either a goto or a gosub to
                the specified line number indexed by the value of EXPR.
                If EXPR is larger than the number of LINENUMs, then
                control passes to the next statement.

        on error  goto  LINENUM

                If the error form is used, only one linenumber is
                allowed.  LINENUM is the line to which control is
                transferred if an error occurs.  A GOTO or CONT
                statement can be used to resume execution.  An error
                inside a named SUB subroutine cannot be resumed from
                or CONTinued.

        sub NAME ( VAR { , VAR ... } }

                Subroutine entry.  May be called by a CALL statement or
                by NAME. A SUB subroutine must be exited by a RETURN or
                END SUB statement.  There should be only one RETURN or
                END SUB statement per SUB definition.  The variables in
                the VAR list become local variables. String and numeric
                arguments are passed by value; array arguments must be
                pre-dimensioned and are passed by reference.

                Example:
                        110  x = foo (7, j)  : rem Pass 7 and j by value.
                        ...
                        2000 sub foo (x,y,z) : rem z is a local variable
                        2010   print x       : rem prints 7
                        ...
                        2080   foo = y+1     : rem return value
                        2090 end sub

                Subroutine definitions may not be nested.

        static VARNAME

                Declares a variable statically local to the
		containing subroutine (between sub ... end sub).
		Non recursive.


        select case EXPR

                Multi-way branch.  Executes the statements after
                the CASE statement which matches the SELECT CASE
                expression, then skips to the END SELECT statement.
                If there is no match, and a CASE ELSE statement is
                present, then execution defaults to the statements
                following the CASE ELSE.

                Example:
                        200 select case x
                        210   case 2
                        ...
                        230   case 3, 4
                        ...
                        270   case else
                        ...
                        290 end select


        dim VAR( d { , d { , d } } ) { , VAR( d { , d { , d } } ) ... }

                Dimension an array or list of arrays (string or numeric). 
                A maximum of 4 dimensions can be used. The maximum
                dimension size is limited by available memory. Legal
                array subscripts are from 0 up and including the
                dimension specified; d+1 elements are allocated.  All
                arrays must be dimensioned before use.

                Example:
                        10 dim a(10)  : rem  An 11 element array.
                        20 for i=0 to 10
                        30   a(i) = i^2
                        40 next i
                        50 print a(5) : rem  Should print 25

        data ITEM { , ITEM }

                DATA statements contain the data used in the READ
                statements. Items must be separated by commas.  The
                items may be either numeric or string expressions,
                corresponding to the type of variable being read.
                Reading the wrong kind of object produces a "Type
                mismatch" error.

                * IMPORTANT DIFFERENCE from other Basic versions *

                String data must be encapsulated with quote marks
		to work correctly.


        read VAR { , VAR }

                Read data from the DATA statements contained in the
                program. List items can be either string or numeric
                variables. Reading past the end the last DATA statement
                generates an error.

        restore { LINENUM }

                The RESTORE statement causes the next READ to use the
                first DATA statement in the program.  If a LINENUM is
                given then the DATA statement on or after that
                particular line is used next.

        rem or "`"

                A remark or comment statement.  Ignored by the program
                during execution, however a REM statement can be the
                target of a GOTO or GOSUB.

        def fnNAME ( VAR { , VAR } ) = EXPR

                Define a user definable function.  Obsolete.

                Example:
                        10 def fnplus(x,y) = x+y
                        20 print fnplus(3,5) : rem prints 8


    FILE AND INPUT/OUTPUT STATEMENTS

        open STRINGEXPR for { input|output|append } as # FNUM

                Open a file. The { input|output|append } parameter
                specifies whether the file is to be read, written or
                appended.  If STRINGEXPR is "stdin" for input or
                "stdout" for output then the console will be used
                instead of a file.  A "file not found" error will
                occur if a non-existant file is specified in an OPEN
                for input statement.  FNUM must be an integer value
                between 0 and 8.

        open STRINGEXPR for random as # FNUM len = VAL

                Opens a random access file.  Only GET and PUT statement
                are allowed to read and write random access files.

        open ... else goto LINENUM

                See OPEN command.
                LINENUM is the line to which control is transferred if
                an error in opening a file occurs.  The variable ERL is
                set to the line number on which the file open error
                occured.

        close # FNUM

                Close a file. Releases the file descriptor and flushes
                out all stored data.

        print  VAL | STRINGVAL { [ , | ; ] VAL ... } { ; }
        ?      VAL | STRINGVAL { [ , | ; ] VAL ... } { ; }
        print # FNUM, VAL ...

                This command will print its parameters tab delimited.
                If a semi-colon is used between parameters then no tab
                is inserted between the parameters.  The print
                output is terminated with a carriage return unless the
                parameter list ends with a semi-colon.  If a file
                descriptor is given then output is redirected to the
                given file.  If a

                        tab(VAL);

                is found in a print statement, then print output will
                skip to the horizontal position specified by VAL.

        print { # FNUM, } using STRINGVAL ; VAR { [ , | ; ] VAR ... }

                Prints formatted numbers.  Legal characters for the
                format string STRINGVAL are: + * $ # . E+ and trailing
                spaces.

                Examples:

                        print using "**$###.##"; 1.23  :' ****$1.23
                        print using "###.##"; 2.12345  :'   2.12
                        print using "#.##E+##"; 2345.6 :'   2.35E+03

        input  STRINGVAR | VAR  { , VAR }
        input  "prompt ", { STRINGVAR | VAR  { , VAR } }
        input  { # FNUM , } { STRINGVAR | VAR { , VAR } }

                Input from the console or from the file specified by
                FNUM. If the input is from the console then a prompt
                string can optionally be printed before input.

                *** NOTE ***

                All input to string variables is "line input"; a whole
                input line will be read into one string variable.  The
                number of comma seperated numeric values in the input
                data must be less than or equal to the number of
                numeric variables in the INPUT statement.  This INPUT
                usage is different from other versions Basic.

        get STRINGVAR

                Gets one character from the console keyboard.
                Blocking (waits for a character).

        fputbyte VAL, # FNUM

                Writes one byte to the file specified by FNUM.
                
        fseek # FNUM, NUM

                Seek to file position NUM in file specified by FNUM.

        get # FNUM, VAL, TYPED-VAR

                Reads one record from a random access file into VAR.

        put # FNUM, VAL, TYPED-VAR

                Write one record to a random access file from VAR.

        dim DBSTRINGVAR as dbm$( STRINGEXPR )
        
                Open a sdbm database file using the filename contained
                in STRINGEXPR.  Creates a database if one doesn't exits.
                This database can be accessed by using or storing to the
                array string variable named by DBSTRINGVAR ( STRINGKEY ).
		Example:
		    mydb$(key$) = somevalstr$
		    print mydb$(key$)
                
        close STRINGVAR
        
                Close a sdbm database file if one using that variable
                name is open.
                

    MATRIX and OBJECT TYPE STATEMENTS

        option base { 0 | 1 }
        mat origin  { 0 | 1 }

                Sets the matrix index origin to either 0 or 1 for all
                MAT statements, including fill.  Defaults to 1.

        mat ARRAY-VAR = EXPR

                Fills a 1 or 2 dimensional array with a constant
                value given by EXPR.  Lower bound = mat origin

        mat ARRAY-VAR = idn ( { EXPR } )

                Fills a 2 dimensional array with an identity matrix.
                The array must have been previously dimensioned.
                
        mat ARRAY-VAR = ARRAY-VAR

                Copys a 2 dimensional array.  The dimensions
                must match.

        mat ARRAY-VAR = ARRAY-VAR { + | * } { EXPR | ARRAY-VAR }

                Adds or multiplies a 2 dimensional array by either
                an expression or another array.  The dimensions must
                be appropriate for matrix addition or matrix
                multiplication.

        mat ARRAY-VAR = ( EXPR ) { + | - | * } ARRAY-VAR

                Adds, subtracts or multiplies a 2 dimensional array by
                an expression.  Note that the parenthesis around the
                expression are required.

        mat ARRAY-VAR = transpose ARRAY-VAR
        mat ARRAY-VAR = trn ARRAY-VAR

                Transposes a 2 dimensional array.  The dimensions of
                the first array must correspond to the transpose of
                the dimensions of the second array.

        mat ARRAY-VAR = invert ARRAY-VAR
        mat ARRAY-VAR = inv ARRAY-VAR
        mat ARRAY-VAR = invert ARRAY-VAR else LINENUM

                Inverts a 2 dimensional square array.  If LINENUM
                is specified, control is transferred to LINENUM if
                the matrix is singular.  Note that the default
                array origin is (1,1).

        mat print ARRAY-VAR
        mat print ARRAY-VAR ;
        mat print #n, ARRAY-VAR
        mat print using STRINGVAL ; ARRAY-VAR

                Prints a 1 or 2 dimensional array.  A trailing
                semicolon will try to pack the data without tabs.
                The format STRINGVAL in MAT PRINT USING applies to
                each element seperately.
                
        fn fft1( 1, ARRAY_ELEMENT, ARRAY_ELEMENT, SIZE_VAL )
                       
                In-place 1d Discrete Fourier Transform of real and
                imaginary arrays of at least size SIZE_VAL, starting
                at the referenced array indexes.  SIZE_VAL must be
                a power of 2.  Uses FFT algorithm.
                
                Example:
                        fn fft1 ( 1, x(0), y(0), 256 )
        
	fn fft1( -1, ARRAY_ELEMENT, ARRAY_ELEMENT, SIZE_VAL )
                       
                Inverse FFT.
                		
                                
        type CLASSNAME

                Creates a structure definition type.  Each field
                requires a separate line.  Legal types are string,
                integer, longint and double.  The definition must
                conclude with an END TYPE statement.  Use the
                DIM AS NEW statement to create records containing
                the structure specified by a TYPE statement.

                Example:
                        300 type person
                        310   name as string * 32 : rem = 31 chars length
                        320   age as integer      : rem  2 byte integers
                        330   weight as double    : rem  8 byte doubles
                        340 end type
                        400 dim friend1 as new person
                        410 friend1.name = "Mark" : friend1.age = 13
                        420 print friend1.name, friend1.age

                Created typed structure elements can only be
                used in expressions and assignment statements.
                
        class CLASSNAME { extends SUPERCLASSNAME }

                Creates a class definition.  Class definitions can then
                be used to create objects with member functions (also
                called methods.)  Classes inherit members from
                superclasses (single inheritance.)

                Example:
                CLASS bar
                  y AS integer
                  z AS PRIVATE double   ' private data
                  s AS PUBLIC string    ' public keyword optional
                  SUB blah(v)           ' public member function
                    this.y = v + 7
                  END SUB
                END CLASS

                DIM b AS NEW bar        ' create object b
                CALL b.blah(1)          ' send message "blah(1)" to b

                CLASS and TYPE definitions are global, and cannot be
                nested inside other class definitions or subroutines.

        dim VAR { ( INT ) } as new CLASSNAME

                Create a record (TYPED-VAR) or object using a
                previously defined structure definition type created
                by TYPE...END TYPE or CLASS..END CLASS.  Optionally
                creates an array of records or objects.


     MISC COMMANDS
 
        option degrees
                Changes the trigonometric functions to use degrees
                instead of radians for all parameters and return
                results.

        randomize EXPR

                Seeds the random number generator with the integer
                EXPR. The pseudo-random number generator should return
                the same sequence when seeded with the same start
                value.  The actual sequence may be system dependant.

        erase VAR

                Un-dimensions a dimensioned array.  Frees memory.

        { let } mid$( STRINGVAR, EXPR1, EXPR2 ) = STRINGEXPR

                Replace the sub-string in STRINGVAR, starting at
                character position EXPR1, with character length EXPR2,
                with the (EXPR2 in length) string STRINGEXPR.

        { let } field$( STRINGVAR, VAL { ,STRINGVAL } ) = STRINGEXPR

                Replace the N-th field of STRINGVAR with STRINGEXPR.

        push VAR { , VAR ... }

                Pushes one or more expressions or variables onto an
                internal stack.  Expressions can be returned using the
                POP function; variables can be restored by using the
                POP statement.  Makes a copy of all array values if
		the variable is a 1d or 2d array (may be useful for
		recursion).

        pop
	pop VAL

                POP statement (see also POP function). Pops VAL
                variables off the internal stack, restoring the value
                of those variables to their pushed values.  Default
		is to pop only one variable.

        exec(STRINGEXPR)

                Executes STRINGEXPR as a statement or command. 
                e.g. exec("print " + "x") will print the value of x.

        cls
                Clear the terminals screen.  Leaves the cursor in the
                upper left corner.  For Applesoft BASIC fans, the
                "home" command will also do this.

        poke ADDR_EXPR, DATA_EXPR  { , SIZE_VAL } 

                Poke a byte into a memory location. Unreasonable
                addresses can cause bus or segmentation errors.
                Use a optional SIZE_VAL of 2 or 4 to poke short or
                long integers to properly aligned addresses.


     NUMERIC FUNCTIONS

        sgn(VAL)

                Returns the sign of the parameter value.  Returns
                1 if the value is greater than zero , zero if equal
                to zero.  -1 if negative.

        abs(x)

                Returns the absolute value of x.

        int(x)
        int(x,0)

                Returns the integer value of x.  Truncates toward
                minus infinity.  The absolute value of x must be
                less than 2^31-1.  The usage int(x, 0) truncates
                towards zero instead of minus infinity.


        floor(x)

                Returns the integer value of x.
                Truncates toward negative infinity.

        sqr(x)

                Returns the square root of x.

        log(x)

                Returns the natural logarithm of x.

        log10(x)

                Returns the logarithm base 10 of x.

        exp(x)

                Returns e^x. e=2.7182818...

        sin(x)
        cos(x)
        atn(x)

                Trigonometric functions: sin, cosine and arctangent. 
                
        atn(y,x)

                4 quadrant arctangent

        pi

                Returns pi, 3.141592653589793... 

        rnd ( EXPR )

                Returns an integer pseudo-random number between 0 and
                int(EXPR)-1 inclusive. If EXPR is 1, then returns a
                rational number between 0 (inclusive) and 1.  If EXPR
                is negative then EXPR seeds the random number generator.

        len( STRINGEXPR )

                Returns the length of the string STRINGEXPR.

        len( TYPED-VAR )

                Returns the length, in bytes, of a typed record
                (one created by DIM AS).

        val( STRINGEXPR | EXPR )

                Value of the expression contained in a STRINGEXPR or
                EXPR.  STRINGEXPR may be a string literal, variable,
                function, or expression.

                For example, VAL("1 + sqr(4)") yields 3.

        asc( STRINGEXPR )

                Returns the ascii code for the first character of
                STRINGEXPR.  A null string returns zero.

        instr(a$, b$ { , VAL } )

                Returns the position of the substring b$ in the
                string a$ or returns a zero if b$ is not a substring.
                VAL is an optional starting position in a$

        det ( ARRAY-VAR )
                
		Returns the determinant of a 2-dimensional
                square array.

        fn dot ( ARRAY-VAR, ARRAY-VAR )
 
                Returns the dot product of two 1-dimensional 
                arrays.


    MISC FUNCTIONS
    
        isarray( VAR )

                If VAR is a dimensioned array, returns the number
                of dimensions, otherwise returns 0.

        ubound( VAR [, EXPR ] )

                If VAR is a dimensioned array, returns the maximum
                legal subscript of the first dimension of that array,
                else returns 0.  Use EXPR to return other dimensions.

        pop

                POP function (see also POP statement). Pops one variable
                value off the stack and returns that value (string or
                numeric).

                (POP can be used as either a statement (with a
                parameter) or a function (no parameter). Note that the
                POP function, unlike the POP statement, does not
                restore the value of the variable pushed, but only
                returns the pushed value.  This use of the POP
                statement is different from the Applesoft usage.)

        varptr( VAR | STRINGVAR )

                Returns the memory address of a variable.

        fn bswap16( VAL )
        
                Returns a byte swapped 16-bit value.
        
        fn bswap32( VAL )
        
                Returns a byte swapped 32-bit value.


        fn version$()
        
                Returns a string including version number, "BE/LE"
                for endianess, OS, and graphics availability
        
        fn bigendian()
        
                Returns 1 if words are stored in memory in bigendian
                byte order, 0 if in little endian byte order
        
        erl

                Returns the line number of the last error.  Zero if the
                error was in immediate mode.  The variable errorstatus$
                gives the error type.

        timer

                Returns a numeric value of elapsed of seconds from the
                computers internal clock.

        timer()

                Returns a elapsed time in an OS dependant format,
		possibly uS, milliseconds or ticks.

        peek( ADDR { , SIZE_VAL } )

                Returns the value of the byte in memory at address ADDR.
                If SIZE_VAL is 2 or 4, returns the value of the 16-bit
                or 32-bit word respectively (if correctly aligned).
                If SIZE_VAL is 8, returns the value of the numeric
                variable located at ADDR.  (peek(varptr(x),8) == x)


    STRING FUNCTIONS
    
        x$ + y$

                String concatenation.

                String concatenation (and the MID$, LEN and INSTR
                functions) can handle strings of up to 32766 characters
                in length (if the memory available to the program
                permits).

        chr$(VAL)

                Returns the ascii character corresponding to the value
                of VAL.

        str$( VAL { , EXPR } )

                Returns a string representation corresponding to VAL.
                If EXPR is present then the string is padded to that
                length.

        format$( VAL , STREXPR )

                Returns the string representation of VAL formatted
                according to the format string STREXPR. The format
                string STREXPR uses the same formatting syntax as the
                PRINT USING statement.

        mid$( a$, i { , j } )

                Returns a substring of a$ starting at the i'th
                positions and j characters in length. If the second
                parameter is not specified then the substring is
                taken from the start position to the end of a$.

        right$(a$, EXPR )

                Returns the right EXPR characters of a$.

        left$(a$, EXPR )

                Returns the left EXPR characters of a$.

        field$( STRINGVAL, VAL { , STRINGVAL } )

                Returns the N-th field of the first string.  If the
                optional string is present then use the first character
                of that string as the field separator.  The default
                separator is a space.  Similar to UNIX 'awk' fields.

                e.g.  field$("1 22 333 4", 3)  returns  "333"

                If VAL is -1 then returns a string with a length
                equal to the number of seperators in the first string.

        hex$( VAL { , EXPR } )
        bin$( VAL { , EXPR } )

                Returns the hexadecimal or binary string representation
                corresponding to VAL.  If EXPR is present then the
                string is padded with zeros to make it that length.

        lcase$( STRINGVAL )

                Returns STRINGVAL in all lower case characters.

        fn math$( "add$", STRINGVAL, STRINGVAL )

                Does arithmetic of up to 250 digits on the decimal
		values described by 2 strings.  Operator keywords
		also include: "sub$" , "mul$" and "div$"


        errorstatus$

                Returns the error message for the last error.


    FILE FUNCTIONS
    
        inkey$

                Return one character from the keyboard if input is
                available. Returns a zero length string { "" } if no
                keyboard input is available.  Non-blocking.  Can be
                used for keyboard polling.

        input$( EXPR { , FILENUM } )

                Returns EXPR characters from file FILENUM. If f is not
                present then get input from the console keyboard.

        fgetbyte( FILENUM )

                Reads one byte from the open file specified by FILENUM
                and returns an unsigned numeric value [0..255].

        eof(FILENUM)

                Returns true if the the last INPUT statement, INPUT$
                or FGETBYTE function call which referenced the text
                file specified by FILENUM tried to read past the end
                of file. (Note that reading the last line of a file
                will not read past the eof mark.  A subsequent read is
                needed to set the EOF flag to true.  Reading past the
                end-of-file will not report an error.)

        fn eol(FILENUM)

                Returns line termination character of previous
                line input statement (usually CR, LF or 0).


    OS SPECIFIC COMMANDS and FUNCTIONS (Mac, linux, MS Windows, etc.)

    Most OS specific commands are only documented in the Readme
    file or Quick-Reference text document appropriate to each
    OS version.  This includes several dozen experimental built-in
    fn functions and macfunction() commands, GUI commands, some
    Mac serial port access functions, some Quicktime MIDI/GIF/JPEG
    support, etc.


    Mac OS X, Unix X11 and MS Windows Graphics Commands:

        graphics 0
        
                Opens a graphics window if graphics are available.
		(Under Unix, if the X11 library is available.)
		May refresh the graphics window if it is already
		open.
        
        graphics moveto VAL, VAL

                Sets the (x,y) location of the graphics pen.

        graphics lineto VAL, VAL

                Draws a line from the current pen location to location
                (x,y) in the graphics window.

        graphics text STRINGVAL

                Draws the text of STRINGVAL at the current pen
		location.

        graphics color REDVAL, GREENVAL, BLUEVAL

                Sets the drawing color.  The range of color values 
		is 0.0 to 100.0   Range and accuracy of the RGB color
		values may be limited, depending on OS and hardware.

    
    Mac OS and MS Windows Graphics Commands:
        
        graphics cls

                Clears the graphics window.

	moveto VAL, VAL

                Sets the (x,y) location of the graphics pen.

        lineto VAL, VAL

                Draws a line from the current pen location to location
                (x,y) in the graphics window.

        fn plot1 ( 0, f$, x$, y$, x0, x1, n)

                Draws an autoscaled plot of the function in f$,
		using the variable named in x$, range x0 to x1,
		up to n points plotted.

    
    Mac OS X, Unix/linux and MS Windows Commands:

        fn kill( STRINGVAL )

                Deletes the file named by STRINGVAL.  Returns 0 if
                successful.


    Mac OS, Unix/linux and MS Windows Functions:

        date$
                Returns a string corresponding to the current date.

        time$
                Returns a string corresponding to the current time.


    MS Windows OS Commands:

        sys( "command.com /c cls" ) 
    
                Clears the text console in the command line version.
    
        sys( "command.com /c dir" ) 
    
                Lists files in current directory to text console.

    
    UNIX/linux and Mac OS X Commands:

        open "pipe:" + STRINGEXPR for input  as # FNUM
        open "pipe:" + STRINGEXPR for output as # FNUM
                
                Opens an input or output pipe with STRINGEXPR as
                the process command string.

                example: open "pipe:/bin/ls -l" for input as #1

        open "socket:" + STRINGEXPR , EXPR for input as # FNUM
        open "socket:" + STRINGEXPR , EXPR for output as # FNUM
                
                Open a socket to the server and port specified by
                STRINGEXPR and EXPR.  The input port must be opened
                before the output port.


    UNIX/linux and Mac OS X Functions:

        sys( STRINGVAL )

                UNIX system call.  The string parameter is given to
                the shell as a command.  Returns exit status.

        system$( STRINGVAL )

                UNIX shell command.  The string parameter is given to
                the shell as a command.  Returns first line of shell's
                standard output response to the command.

        getenv$( STRINGVAL )

                Returns value for environment name STRINGVAL.
    
        fn pid()
        fn ppid()
        fn uid()

                Returns system process and user info.

        fn sleep( VAL )

                Sleeps process for VAL seconds.  Fractional values
		for the sleep time are allowed.

        fn shmem( key, mode, length )

                Returns pointer to shared memory segment or 0 for
                fail.  If mode > 0 then creates shared memory area
                (see unix shmget), otherwise tries to find existing
                one matching key.  If length = 0 then releases
                shared memory area.  Use of only one shared memory
                area at a time is supported.  Length is in bytes.


    UNIX/linux and Mac OS X Terminal Command-line Functions:

        argv$
                Returns the UNIX shell command line arguments.

        fn sysfork()

                Forks process.  Returns 0 to the child process and
                the pid of new process to the parent process.

        exit( EXPR )

                Exits Basic interpreter with status value of EXPR.


    Mac OS Commands:


        morse STRINGVAL { , VAL, VAL, VAL, VAL }

                Plays morse code through the speaker.
                The parameters are: word-speed-wpm, volume{0..100},
                dot-speed-wpm, frequency{in Hz or cps}

        sound VAL, VAL, VAL 

                The parameters are:
                frequency{in Hz}, seconds_duration, volume{0..100}

        say STRINGVAL

                Speaks STRINGVAL if the Speech Manager Extension is
                resident.  Try "say a$,200,46,1" for faster speech.
                The last parameter is the voice selector.


    Macintosh-only GUI Commands:

        *** NOTE ***
                Many MacOS specific functions and commands are only
                documented in the Chipmunk Basic quick reference file.

        gotoxy VAL, VAL

                Set the horizontal and vertical location of the
                text output cursor.  (0,0) is the upper left corner.

        window x, y, char_cols, char_lines

                Change the text console window position and size.

        graphics drawtext STRINGVAL

                Draws the text of STRINGVAL at the current pen
		location.

        graphics window x, y, pixel_width, pixel_height
	
                Change the graphics window position and size.

        graphics oval  x, y
	
                Draws oval centered at current pen location.

        graphics rect x, y, x2, y2
	
                Draws rectangle with the given pixel coordinates
		for the top/left and bottom/right points.

	open "SFGetFile" for input  as #FNUM
        open "SFPutFile" for output as #FNUM

                Puts up a standard file dialog for the file name.

        files { STRINGVAL }

                Displays a listing of files in the named or current
                directory.


    Mac OS Graphics Functions:

        fn scrn (XVAL, YVAL, CSELVAL) 

                Returns the graphics pixel color at the point (X,Y)
		Color select value can be 1 for red, 2 for green,
		or 3 for blue.


    Mac OS Functions:

        fre
                Returns the amount of memory left for program use. 
		(Mac OS Classic Only).

        pos(VAL)

                Returns the horizontal position of the text cursor.
                If VAL is negative returns the vertical position.

        errorstatus$

                Also returns the full path name of the program and
                files opened by SFGetFile and SFPutFile (the full
		path name must be less than 254 characters.)


    Mac OS menu items:

        Open or O       Puts up a dialog box to allow selection
                        of a program file to load.  Basic Program
                        file names must end with a ".bas" suffix.

        Copy            Allow copying text from the text console or
	                picts from the graphics window.

        .               Command-period will stop program execution.

    
    UNIX/linux and Mac OS X Terminal pragmas:

        #cbas#run_only

                When used in a Basic program file, upon load sets
                the  Chipmunk  Basic  interpreter to run-only mode.
                Interactive mode disabled.  Thus the Stop and  End
                commands and the use of Ctrl-C will quit the
                interpreter.


    VARIABLES and DATA TYPES

	Variable names can be up to 31 significant characters in
	length, starting with a letter, and optionally followed by
	letters, digits, underscores, or an ending dollar sign or
	percent character.  Variable names are case insensitive.
	Variables can hold floating point values (IEEE double),
	short integers, or strings of up to 254 characters.  If a
	variable name ends with a "$" character, it holds a string
	value, otherwise it holds numeric values.  If a variable
	name ends with the "%" character it may be limited to
	holding only integer values from -32768 to 32767.


    OPERATORS

        The following math operators  are available:

                ^       exponentiation
                *       multiplication
                /       division
                mod     remainder
                +       addition
                -       subtraction

        logical operator: (any non-zero value is true)

                not     logical not
		        (use xor 0xffff for a bitwise not)

        bitwise operators:

                and     bitwise and
                or      bitwise or
                xor     bitwise exclusive-or

        comparison operators:

                <=      less than or equal
                <>      not equal to
                >=      greater than or equal
                =       equal
                >       greater than
                <       less than

        x$=y$, x$y$, x$<=y$, x$>=y$, x$<>y$

                String comparisons; result is 1 if true, 0 if false.

        Operator precedence (highest to lowest):

                ( )
                functions()
                ^
                -{unary_minus} 
                * / mod
                + -
                = < > <= >= <>
                not
                and
                or xor  imp eqv


    RESERVED WORDS AND SYMBOLS

        + - * / ^ mod  and or xor not  > < >= <= <> = ()
        sqr log exp sin cos tan atn  pi
        abs sgn int rnd peek val asc len
        mid$ right$ left$ str$ chr$  lcase$ ucase$
        goto  if then else endif  gosub return
        for to step next  while wend  select case
        rem  let  dim erase  data read restore   field$
        input print open for output append as close# load save
        random lof loc get put   
        inkey$  input$ eof  files  fgetbyte# fseek# fputbyte
        run stop end exit quit cont  renum  new clear
        date$ time$ timer  sound morse say  doevents
        home cls gotoxy htab vtab pos 
        graphics sprite pset moveto lineto window scrn mouse
        varptr peek poke fre push pop  isarray
        sub call usr  def fn
        type class extends  string integer single double
        asin acos sinh cosh tanh log10 floor true false ubound

        eqv imp  static  option degrees radians redim
        msgbox  do loop until break
        method private public local   menu dialog memstat()
        draw play  bload bsave  min max mat
        each  resume  function
        key is each set width swap dbm$


    CONVENTIONS

        EXPR            an expression that evaluates to a numeric value.
        STRINGEXPR      a string expression.
        VAR             a numeric variable.
        STRINGVAR       a string variable. Name must end with a "$".
        INTEGERVAR      a 16-bit variable. Name must end with a "%".

        All program lines must begin with a line number unless the
        whole program is loaded from a file.
        Using spaces (indentation) between the line number and
        program statements is legal.  Line numbers can be
        between 1 and 2147483647.  Programs lines must be no
        longer than 254 characters in length.

        Variable names starting with "fn" are reserved for the
        (obsolete) def fn functions.

        Hexadecimal numbers can be entered by preceding them with
        a "0x" as in 0x02ae, or by "&h" as in &h0172.

        Multiple statements may be given on one line, separated by
        colons:

                10 INPUT X : PRINT X : STOP


    DIAGNOSTICS

        Some errors can be caught by the user program using the
        "on error goto" command. If no error trapping routine has been
        supplied then program execution is terminated and a message is
        printed with the corresponding line number.


    CHANGES

        v3.6.6(b0) - added mat read
                   - fixed a gosub error message
                   - fixed mat assign bug
        v3.6.5(b3) - fixed mat multiply
                   - fixed bug in format$() with leading zeros
                   - fixed bug in exit while statement
                   - fixed bugs with empty for and empty edit statements
                   - fixed object string bug and object array bug
        v3.6.4(b7) - added local statement
        v3.6.4(b5) - add fn eval(), #ifndef _chipmunkbasic_
        v3.6.4(b2) - add ternary if(,,)
        v3.6.4(b1) - add det(), fn dot(), allow next j,i
	           - bsave & mat inv size limits increased
        v3.6.4(b0) - added fn sleep(), dim as string
                   - fixed rnd() scaling, format$()
        v3.6.3(b7) - fixed socket read eof, object print, fft
        v3.6.3(b4) - fixed exit for, sub return, mat a*b
        v3.6.3b1 - fixed randomize/rnd bug, get bug
        v3.6.3b0 - added sdbm database commands
        v3.6.2b9 - fixed bug in atn() with expression parameter
        		 - added fn version$(), open pipe for output
        v3.6.1b2 - fixed bug in integer LET command
        v3.6.1   - changed precedence of unary minus (-) to below
                     exponentiation (^) to match ANSI/ISO specification.
                 - changed default matrix origin to 1
                 - added mat print commmand.
        v3.6.0   - added unix exit status, fn kill(), fn bigendian()
        v3.5.9b4 - fixed def fn array parameters, added atn(x,y)
        v3.5.9b3 - fixed bugs with if():, instr(), mid$ & val("..")
        v3.5.9   - fixed bugs in format$() & intl. string comparisons
        v3.5.8b7 - fixed  bugs in array assignment, the read/data
                   statement, fputbyte(), and ELSEIF nesting
                 - added the MAT INVERT statement
        v3.5.8   - changed int() to round towards -infinity.
        v3.5.7b3 - added network socket i/o
        v3.5.7b2 - fixed unix/linux rnd() function
        v3.5.7b1 - fixed a problem with array indexes > 65k
        v3.5.3  - allow integer (i%) variables as for/next loop indices
        v3.4.7  - lower precedence of NOT operator
                - disabled ON GOTO range checking
        v3.4.6  - added MAT matrix statements
        v3.4.0  - OPEN ELSE added
        v3.3.4  - changed integer conversion to rounding
                - changed sub return values to: sub_name = x
                - added reserved words for: true false
        v3.3.3  - added acos, tanh, log10
        v3.2.8  - added class definitions
        
        Many others ...

    BUGS

        Many.  Perhaps competitive with Central American rain forests.

        FOR/NEXT loops with integer indices require a variable in the
        NEXT statement. Integer arrays can only have a dimension of
        one and will only work in assignment (LET) statements.  All
        arithmetic on integer variables is done using floating point
        arithmetic.  DIM AS DOUBLE and DIM AS INTEGER statements are
        ignored.

        Many string functions (except +, MID$, LEN and INSTR) silently
        truncate their results to 254 characters (e.g. without
        warning). All string function may silently truncate strings
        longer than 32766 characters. Any operation on strings longer
        than 254 characters will cause the program to run slower.

        Comments starting with ' sometimes can't be used after
        statements that can end with a string parameter. ( : '
        should always work.)

        Any variables used as a CLASS, or TYPE, globally overide all
        local variables of the same names.  Local TYPE'd variables
        must be declared globally as TYPE'd variables.  Named SUBroutines
        are slower than GOSUBs. The combined length of a SUBroutine name
        and any local variables declared STATIC must be less than 29
        characters.

        Can't CONTinue from an error inside a named SUB subroutine.

        The PRINT USING format string doesn't recognize comma's,
        underscores and many other common format characters.

        Mac OS screen editing will only recognise the last line
        modified before a RETURN or ENTER key.  The EDIT command and
        Mac screen editing are incompatible.

        There are many undocumented graphics and sprite commands
        and keywords in the Mac OS port.  See the accompanying
        README and Chipmunk Basic quick-reference file.


    DISCLAIMER

        There is no warranty that this document is accurate.

    SEE ALSO

        The Chipmunk Basic Home Page:

                http://www.nicholson.com/rhn/basic

    
    AUTHORS

        David Gillespie wrote basic.p 1.0 and the p2c lib.
        Ron Nicholson (rhn AT nicholson.com) added file i/o, graphics
        and did the Unix, Macintosh and PowerMac port. (1990-1997Nov)

    Portions of this document are Copyright (C) 1989 Dave Gillespie.
    Copyright (C) 1994,1998,2006,2007,2012 Ronald H. Nicholson, Jr.
    All rights reserved.  				(ver.070827)
    "Applesoft" is a trademark of Apple Computer, Inc., etc.