XDUMP

  - used to "dump" the GPRs or program storage
  
  Format 1:  XDUMP        comment

    - produces a hexadecimal dump of the GPRs


  Format 2:  XDUMP  D(X,B),length

    - produces a hexadecimal dump of storage starting from D(X,B) for 
      length bytes
    
    - a label can be substituted for D(X,B)
    
    - an expression that resolves to an integer value can be 
      substituted for length


  If the line XDUMP NUM1,RESULT2+4-NUM1 was coded somewhere in
  the program, a hexadecimal dump of the entire storage area would be 
  produced.

XREAD

  - used to read an input record from the file indicated on FT05F001 
    DD card or from instream data
  
  Format: label  XREAD  D(X,B),length

    - reads length bytes into the input buffer located at D(X,B)

  
  Sets the Condition Code:
  
    Code     Meaning
     0       Successful read
     1       End of file reached
  
  
  Example:  XREAD  BUFFER,80 
  
      Assuming that BUFFER DS  CL80 is located in storage

XDECI

  - used to convert a number from its character representation to its 
    binary representation so that math can be performed
    
  Format: label  XDECI  R,D(X,B)
    
    - converts the number at D(X,B) to binary and stores it in R
  
  
  - Stops scanning when a space is reached
  
  - 1st character may be a digit or a plus (+) or minus (-)
    sign
    
  - Register 1 is set to the address of the next value to read
  
  Sets the Condition Code:

     Code     Meaning
      0       Converted number is 0
      1       Converted number is less than 0
      2       Converted number is greater than 0
      3       Attempt to convert an invalid number


   XDECI  3,BUFFER   Convert 1st number on an input record

   XDECI  4,0(,1)    Convert 2nd number on the input record

XDECO

  - used to convert a number from its binary representation to its 
    character representation so it can be printed
    
  Format: label  XDECO  R,D(X,B)
  
    - converts the binary number in register R to printable 
      characters and stores it at D(X,B)
    
    - Number is converted to a 12 byte character representation
    
    - If number is negative, a minus sign is printed to left of 1st
      digit
  
  
  XDECO  3,NUM1   Convert number in register 3 to printable format and
                  place it in NUM1, which is defined as NUM1 DS CL12

  XDECO  4,NUM2   Convert number in register 4 to printable format and 
                  place it in NUM2, which is defined as NUM2 DS CL12

XPRNT

  - used to print a print line
  
  Format: label XPRNT  D(X,B),length

    - prints length bytes of the print line located at D(X,B)

  
  - Print lines must be explicitly defined in program storage
  
  - usually 132 characters long

  - 1st character is used for carriage control
    
       space    single spacing
         0      double spacing
         -      triple spacing
         1      new page


  XPRNT  LINE1,132   Print the print line
  
  >>> more code here <<<
  
  LINE1   DC   CL1‘ ’
          DC   CL16’Num1 is equal to’
  NUM1    DS   CL12
          DC   CL5‘ ’
          DC   CL16’Num2 is equal to’
  NUM2    DS   CL12
          DC   CL70‘ ’