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Built-in Assembler DB, DW, and DD DirectivesLanguage:
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Built-in Assembler DB, DW, and DD Directives
The built-in assembler supports three assembler directives: DB (define byte), DW (define word), and DD (define double word).
Dir Operand Type Value Range Built-in Assembler Generates
DB Constant expression 128 to 255 1 byte
Character string Any length Sequence of bytes corresponding
to ASCII code of each character
DW Constant expression -32,768 to 65,535 1 word
Address expression Near pointer (offset word)
DD Constant expression -2,147,483,648 1 double word
to 4,294,967,295
Address expression Far pointer (offset word
followed by segment word)
The data generated by the DB, DW, and DD directives is always stored in the code segment.
To generate uninitialized or initialized data in the data segment, use normal Pascal var or const declarations.
Here are some examples of DB, DW, and DD directives:
Dir Operand Result
DB 0FFH One byte
DB 0,99 Two bytes
DB 'A' Ord('A')
DB 'Hello...', 0DH,0AH String + CR/LF
DB 12,"Turbo Pascal" Pascal-style string
DW 0FFFFH One word
DW 0,9999 Two words
DW 'A' Same as DB 'A',0
DW 'BA' Same as DB 'A','B'
DW MyVar Offset of MyVar
DW MyProc Offset of MyProc
DD 0FFFFFFFFH One double-word
DD 0,999999999 Two double-words
DD 'A' Same as DB 'A',0,0,0
DD 'DCBA' Same as DB 'A','B','C','D'
DD MyVar Pointer to MyVar
DD MyProc Pointer to MyProc
The only kind of symbol that can be defined in a built-in assembler statement is a label. All variables must be declared using Pascal syntax.
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