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 to insert a block of source code from the named directvies into the current source module. Mohaimen Himu October 24, at 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.
You get question papers, syllabus, subject analysis, answers – all in one app. DQ — Define Quadword This directive is used to define a variable of type quadword or to reserve storage location of type quadword in memory. If the word is at even address can read a memory in 1 bus cycle.
DB — Define Byte This directive is used to declare a byte type variable or assemblsr store a byte in memory location.
Each time the assembler finds the name nicroprocessor 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. This directive is used to define a variable of type quadword or to reserve storage location of type quadword in memory. This directive is used to group the logical segments named after the directive into one logical group segment. This directive is used to define a variable which is 10 bytes in length or to reserve 10 bytes of storage in the memory.
Newer Post Older Post Home. DW — Define Word This directive is used to define a variable of type word or to reserve storage location of type word in memory. When EVEN is used the location counter will simply incremented to next address and NOP instruction is inserted in that incremented location.
The works directly with only 4 physical segments: 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.
8085 Assembler User Guide
The specialty of these statements is that they are effective only during the assembly of a program but they do not generate any code that is machine executable. MODEL- This directive is used for selecting a standard memory model for the assembly language program. If the word starts at an odd address, the will take 2 bus cycles to get the data. GROUP This directive is used to group the logical segments named after the directive into one logical group segment. DD — Define Doubleword This directive is used to define a variable of type doubleword or to reserve storage location of type doubleword in memory.
DT — Define Ten Bytes. DD — Define Doubleword. DATA- This directive indicates the beginning of the data segment. This is because the END directive terminates the entire program.
ALIGN- This directive will tell the assembler to align the next instruction on an address which corresponds to the given value. DQ — Define Quadword. Define Ten bytes [DT]- It is used to define the data items that are 10 bytes long. CODE [name] The name in this format is optional.
MICROPROCESSOR AND MICROCONTROLLER: Assembler Directives of /
This directive is used to give a name to some value or to a symbol. A series of words can be read much more quickly if they are at even address. Its format is as follows: Microprocessof our mobile app and study on-the-go. Each memory model has various limitations depending on the maximum space available for code and data. Executable statements- These are the statements to be executed by the processor. Define Double word [DD]- It defines the data items that are a double word four bytes in length.
This directive tells the assembler the microprocesssor of the logical segment it should use for a specified segment.
Assembler directives- These are the statements that direct the assembler to do something. This directive is used to declare a byte type variable or to store a byte in memory sasembler.
DW — Define Word. CODE- This assembler directive indicates the beginning of the code segment. As the name says, it directs the assembler to do a task. Write short notes on assembler directives. EQU This directive is used to give a name to some value or to a symbol. It consists of the entire instruction set of Engineering in your pocket Download our mobile app and study on-the-go.
END- This is placed at the end of a source and it acts as the last statement of a program.