Forth String Words.
                        as used by superforth 64



  Note: s=string name. n=numeric. f=flag.


  Notice that when a string is compiled into a dictionary definition
   for use with the following string manipulators it is set up as follows.
  Forth name field: lfa : cfa : pfa - containing - string length byte
  then the string itself. (forth 79)
    When a definition holding a string is encoutered in the input stream
  the address of the first value in the parameter field is left on the stack.
  Words that output such strings use the value at that address
  as a counter for the string length.



   Forth word: $variable :creates a string variable.
    ( n ---) compile time. ( --- addr) run time.
    example:  20 $variable test  :  allocates 20 bytes (not cells) into
    a dictionary word called test. Execution of test leaves address on stack.


   Forth word: $constant  : define string constant.
    ( ---) compile time. ( --- addr) run time.
    Example: $constant string1 "testing" : creates constant string called
    string1 into dictionary. The length of the string is left in the
    byte preceding the actual string in the dictionary.


   Forth word: $clr : clear string in pad or variable.
    ( s ---) 
    example: test $clr or pad $clr                                                  clears the length byte in the string variable or pad.


   Forth word: "  :immediate string.
    ( --- s)  example: " this is a string"
    the string is put into the pad area and the address is left on the stack.
    It must be delimited by a closeing quote.


   Forth word: "" : null string.
    ( ---)   example: "" : leaves a null string in the pad area.
    and the pad address on the stack.


   Forth word: $. : display a string from variable or pad.
    ( s ---)  example: test $. or pad $. : leaves address of the string at test
    on stack then outputs it to the current display device.


   Forth word: $cmp : compare strings.
    ( s1 s2 --- f) compares 2 strings to see if they are identicle.
    flag status: -1 if s1 < s2: 0 if equal : 1 if s1 > s2.                          flag is left on stack when $cmp is finished.


   Forth word: $input : inputs a string from the curent input device.
    ( --- s) After encoutering $input in the input stream
    $input stops and waits for input from a current input device and
    is terminated with a cr. the string is then transfered to the
    pad and the pads address is left on the stack.


   Forth word: $val : converts numeric string to a numeric value.
   ( s1 --- n) example: " 123" pad $val : 
   in the example the immdiate string 123 is placed in the pad
   the pads address is placed on the stack then $val will convert it
   to a 16 bit numeric. Note: you should abort is the string
   contains non numeric charactors.



    These are some of the high level definitions in this system.
  also some of these definitions may need or refer to code definitions
  these I do not care to take apart nor discus.
  What i have given here is the basic concept of the use of some string
  words for use with a forth system. It is up to You to fill the space
  between the :  ;  I hope this small effort helps.


                                                         Jim