Defining Types of Data ?

The subsequent format is used for defining data definition: 

Format for data definition: 

{Name} 

Name -   a program references the data item through the name though it is non-compulsory.

Directive: Specifying data type of assembly.

Expression: Signify a value or evaluated to value.

All directives are listed below:

Directive                      Description                 Number of Bytes

DB                              Define byte                             1 

DW                             Define word                            2 

DD                              Define double word                4 

DQ                              Define Quad word                  8 

DT                              Define 10 bytes                       10 

DUP Directive is used to duplicate the fundamental data definition to 'n' number of times.

ARRAY                                  DB                              10 DUP (0)

In the above statement ARRAY is the name of data item that is of byte type (DB). This array comprises 10 duplicate zero values which is 10 zero values.

EQU Directive is used to define a name to a constant

  CONST                                 EQU                            20

Kinds of number employed in data statements can be Binary, octal, decimal, Hexadecimal and ASCII. Above statement states a name CONST to a value 20. 

Some other instances of employing these directives are:

TEMP                           DB                 0111001B                   ; Binary value in byte operand 

                                                                                                 ; named temp

VALI                                      DW                 7341Q                         ; Octal value assigned to word 

                                                                                     ; variable

Decimal                       DB                  49                                ; Decimal value 49 contained in 

                                                                                    ;  byte variable

HEX                            DW                 03B2AH                     ; Hex decimal value in word

                                                                                                ; operand

ASCII                                     DB                  'EXAMPLE'              ; ASCII array of values.