Important Assembler Directives of the Microprocessor Data declaration directives: DB, DW, DD, DQ, DT ASSUME END directives EQU. The words defined in this section are directions to the assembler, not instructions for the Richa Upadhyay Prabhu. Microprocessors. Introduction To Segmentation: The microprocessor has 20 bit . The DW directive is used to tell the assembler to define a variable of type.

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Constants are identified by type: They generate and store information in the memory. Furthermore, the question mark? In an assembly language program labels are used to give names to memory addresses. The general format of the PROC directive is:.

Abstract This term paper includes the use of assembler directives in microprocessor and the various assembler directives used in Intel microprocessorits format with various examples. Learn How to Order Essay Online.

the use of assembler directives in microprocessor

But leave the bytes un-initialized. The directive ENDP informs assembler the end of a procedure. For example, if you want to call a procedure, which in a program module assembled at a different time from that which contains the CALL instruction, you must tell the assembler that the procedure is external.

So in directoves to test the program with a different set of data, one need not change the program but only have to alter the data. This is a user defined segment name. The assembler micdoprocessor ignore any statements after an END directive, so you should make sure to use only one END directive at the very end of your program module. The DS register data segment register is to be loaded with the starting address of the data segment, given by the operating directivves for the label DATA in the program.

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This directive informs the assembler to reserve the number of bytes of memory space equal to asembler number of characters in the string named MESSAGE, and initialize the memory locations with ASCII codes of the these characters. The name of the segment is used as the prefix of the ENDS directive. This directive informs the assembler that the names, procedures and labels following this directive have already been defined in some other program modules.

This assembler ignores statement s after an END directive. If any value or symbol is mciroprocessor many times in an assembly language program, a name is given to the value or symbol to make programming easier and simpler.

Each time the assembler finds the given name in the program, it replaces the name with the value or symbol which has already been equated with that miccroprocessor.

In the data definition informs assembler that the value of the variable is not known and hence, it is not to be initialized. This directive informs the assembler to reserve two bytes one word of consecutive memory locations for the variable named SUM and initialize it with the value The assembler will then put this information in the object code file so that the linker can connect the two modules together.

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The general format for the EQU directive is:. It also finds out codes of the instructions from the instruction machine, code database and the program data. In a given directive statement, there may be single initial value or multiple initial values of the defined variable.

It has been defined with EQU directive in another program module. The directive DQ defines a quadword- type variable.

the use of assembler directives in microprocessor | CustomWritings

Its general format is:. The directive EQU is used to give a name to certain value or symbol. The directive ENDM is used to inform assembler that this is the end of a macro. Memory locations are initialized with ,, , and The above directive tells the assembler that the name of the stack segment assembldr by the programmer is STACK.

Type NEAR indicates that the procedure is in the same segment of memory. This name is a user defined segment name.

There are several other models too. The content of the location counter holds the address of the memory location assigned to an instruction during assembly process. In many cases the program is optimized and kept unaltered for the specific application.

The ENDS directive informs assembler that this is the end of the segment.