Using the Section Directive · Setting up the Linker · Running the Assembler from the Command Line MICROPROCESSOR INSTRUCTION REFERENCE ACI. The most commonly used assembler directives are ORG, DB, DW, EQU, and END. For example, 0 ORG C 1 00H directive informs the assembler to assemble. Assembly Language Format Assembler Example Description. Directive. ORG ( Origin) ORG H The *Please Refer to Assembly Code Summary.

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Define Quad word [DQ]- This directive is used to tell the assembler to declare variable 4 words in length or to reserve 4 words of storage in memory. DATA- This directive indicates the beginning of the data segment. Mohaimen Himu October 24, at Define Ten bytes [DT]- It is used to define the data items that are 10 bytes long. This directive is used to define a variable which is 10 bytes in length or to reserve 10 bytes of storage in the memory.

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DB — Define Byte. They are classified into the following categories based on the function performed by them- Simplified segment directives Data allocation directives Segment directives Macros related directives Code label directives Scope directives Listing control directives Miscellaneous directives. CODE- This assembler directive indicates the beginning of the code segment. If microprocrssor word is at even address can read a directkves in 1 bus cycle.

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END- This is placed at the end of a source and it acts as the last statement of a program. As the name says, it directs the assembler to do a task. Rest will be added with time…….

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This shortens the source code. Assembly language consists of two types of statements viz.

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Define Double word [DD]- It defines the data items that are assembper double word four bytes in length. Posted by k10blogger at 2: This directive is used to define a variable of type word or to reserve storage location of type word in memory. EVEN This directive instructs the assembler to increment the location of the counter to the next even address if it is not already in the even address. MODEL- This directive is used for selecting a standard memory model for the assembly language program.

Executable statements- These are the statements to be executed by the processor.

This directive is used to give a name to some value or to a symbol. CODE [name] The name in this format is optional. DW — Define Word This directive is used to define a variable of mixroprocessor word or to reserve storage location of type word in memory. Each memory model has various limitations depending on the maximum space available for code and data. This directive is used to define a variable of type quadword or to reserve storage location of type quadword assmbler memory.

Newer Post Older Post Home. Its format is as follows: The specialty of these statements is that they are effective only during the assembly of a program but they do not generate any xssembler that is machine executable. It consists of the entire instruction set of This directive tells the assembler the name of the logical segment it should use for a specified segment.

DT — Define Ten Bytes. Assembler directives- These are the statements that direct the assembler to 8805 something. This directive is used to define a variable of type doubleword or to reserve storage location of type doubleword in memory.

Each time the assembler finds the name in the program, it will replace the name with the value or symbol you given to that name.

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ENDS This directive is used with name of the segment to indicate the end of that logic segment. The works directly with only 4 physical segments: INCLUDE- This directive is used to tell the assembler to insert a block of source code from the named file into the current source module.

This directive is used to group the logical segments named after the directive into one logical group segment. This directive instructs the assembler to increment the location of the counter to the next even address if it is not already in the even address.

DB — Define Byte This directive is used to declare a byte type variable or to store a byte in memory location. The assembler directives can be divided into two categories namely the general purpose directives and the special directives.

When EVEN is used the location counter will simply incremented to next address and NOP directves is inserted in that incremented location. EQU This directive is used to give a name to some value or to od symbol. Download our mobile app and study on-the-go.

A series of words can be read much more quickly if they are at even address. DQ — Define Quadword This directive is used to define a variable of type quadword or to reserve storage location of type quadword in memory. You get question papers, syllabus, subject analysis, answers – all in one app. DD — Define Doubleword.

Last modified: December 28, 2019