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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This directive is used lf define a variable of type word or to reserve storage location of type word in memory. 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. This shortens the source code. As the name says, it directs the assembler to do a task.
8085 Assembler User Guide
This directive is used to insert a block of source code from the named file into the current source module. This directive is used to define a variable of type quadword or to reserve storage location of type quadword in memory. A series of words can be read much more quickly if they are at even address. The works directly with only 4 physical segments: Assembler directives- These are the statements that direct the assembler to do something.
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.
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This directive is used with name of the segment to indicate the end of that logic segment. CODE [name] The name in this format is optional.
Engineering in your pocket Download our mobile app and study on-the-go. When EVEN is used the location counter will simply incremented to next address and NOP instruction is inserted in that incremented location.
Assembler User Guide
If the word starts at an odd address, the will take 2 bus microprocrssor to get the data. 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. Executable statements- These are the statements to be executed by the processor. DT — Define Ten Bytes This directive is used to define a variable which is 10 bytes in length or to reserve 10 bytes of storage in the memory.
DD — Define Doubleword. DB — Define Byte This directive is used to declare a byte type variable or to store a byte in memory location. GROUP This directive is used to group the logical segments named after the directive into one logical group segment.
END- This directoves placed at the end of a source and it acts as the last statement of a program. This directive is used to define a variable which is 10 bytes in length or to reserve 10 bytes of storage in the 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.
ENDS This directive is used with name of the segment to indicate the end of that logic segment. Assembly language consists of two types of statements viz. DQ — Define Quadword. They are classified into the following categories based on the function performed by them- Simplified segment directives Data allocation directves Segment directives Macros related directives Code label directives Scope directives Listing control directives Miscellaneous directives.
This directive is used to declare a byte type variable or to store a byte in memory location.
MICROPROCESSOR AND MICROCONTROLLER: Assembler Directives of /
Define Ten bytes [DT]- It is used to define the data items that are 10 bytes long. This is because the END directive terminates the entire program. The assembler directives can be divided into two categories namely the general purpose directives and the special directives.