Introduction To Segmentation: The microprocessor has 20 bit address pins; these are capable of addressing 1MegaByte memory. Causes all segments to default to DWORD alignmentP enabled assembly of all instructions (see) enabled assembly of instructions . This directive tells the assembler the name of the logical segment it should use for a specified segment. For example ASSUME CS:CODE, tells.

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Each memory model has various limitations depending on the maximum space available for code and data.

The works directly with only 4 physical segments: The started segment is also assigned a name, i. The Addressing Modes. Its format is as follows: Newer Post Older Post Home. CODE- This assembler directive indicates the beginning of the code segment. Assembler Memory models Each model defines the way that a program is stored in the memory system.

END- This is placed at the end of a source and it acts as assemblsr last statement of a program. There are several other models too. Posted by k10blogger at 2: Segmentation helps in the following way. Newer Post Older Post Home. This directive is used to refer to the length of a data array or a string.

  ISO 15589-1 PDF

DT — Define Ten Bytes.

Write short notes on assembler directives

This directive is used to give a name to some value or to a symbol. Each module is individually assembled, tested, and debugged. Write short notes on assembler diirectives. It is the task of the assembler designer to select the suitable strings for using them as directives,pseudo operands or reserved words and decides syntax.

Macro Assembler Directives

Same is the assemmbler with stack and extra segments also, which are only different type of data storage facilities. Offset Of A Label: This directive is used to define a variable of type quadword or to reserve storage location of type quadword in memory. The final executable map of the assembly language program is prepared by the loader at the time of loading into the primary memory for actual execution.

A series of words can be asembler much more quickly if they are at even address.

ENDS This directive is used with name of the segment to indicate the end of that logic segment. Define Quad word [DQ]- This directive is used to tell the assembler to declare variable 4 words in length direvtives to reserve 4 words of storage in memory. The assembler prepares the relocation and linkages information subroutine, ISR for loader. And are typically used to add or subtract displacements 8 or 16 bit to base or index registers or stack or base pointers.


Assembly language consists of two types of statements viz. The PROC directive marks the start of a named procedure in the statement.

EQU This directive is used to give a name to some value or to a symbol. MODEL- This directive is used for selecting a standard memory model for the assembly language program.


When EVEN is used directoves location counter will simply incremented to next address and NOP instruction is inserted in that incremented location. Generally, the program does not know the exact physical address of an instruction. Based on this information and the information generated by the assembler, the loader generates an executable map of the program and further physically loads it into the memory and transfers control to for execution.

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