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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It will initialize the 10 bytes with the values 11, 22, 33, 44, 55, 66, 77, 88, 99, and 00 when the program is loaded into memory to be run. The above directive tells the assembler that the name of the code segment is CODE.
Assembler Directives & Macros
In order for the modules to link together correctly, any variable name or label referred to in other modules must be declared PUBLIC in the module in which it is defined. This directive informs assembler to reserve five bytes of consecutive memory space for the variable named ARRAY.
It is an operator to determine the number of elements in a data item such as an array or a string. The directive PROC indicate the start of a procedure. This directive informs assembler to reserve 16 bytes of consecutive memory locations.
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 name. The type FAR indicates that the procedure to be called is in some other segment of memory.
Additional terms are often added to a SEGMENT directive statement to indicate some special way in which we want the assembler to treat the segment. The content of the location counter holds the address of the memory location assigned to an instruction during assembly process.
Without this WORD addition, the segment will be located on the next available paragraph byte address, which might waste as much as 15 bytes of memory. The general formula is:.
the use of assembler directives in microprocessor
The name of the segment is used as the prefix of the ENDS directive. CustomWritings We can do your essay! There are several other models too. The name is given before the directive MCRO which tells the assembler the beginning of a macro.
These instructions are instructions to the assembler, linker and loader. Constants are identified by type: 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.
The directive ENDP informs assembler the end of a procedure. This name is a user defined segment name.
This is a user defined segment name. The general format for Midroprocessor directive is:.
The above directive informs assembler to reserve four bytes of memory locations for the variable named NUMBER and initialize with the number The above directive tells the assembler that the name 88086 the stack segment used by the programmer is STACK. Loader linker further converts the object module prepared by the assembler into executable form, by linking it with other object modules and library modules.
The above directive informs assembler to reserve 10 bytes of consecutive memory locations for the variable named NUMBER and initialize with the above specified values. Learn How to Order Essay Online. It stores addresses and data of the subroutines, saves the contents a specified register or memory locations after PUSH instruction, etc. I Definition An assembler directive is a message to the assembler that tells the assembler something it needs aasembler know in order to carry out the assembly process; for example, an assemble directive tell the assembler where a program is to be cirectives in memory.
If type is not specified, the assembler assumes it NEAR. But leave the bytes un-initialized. In many cases the program is optimized and kept unaltered for the specific application. The defined variable may have one or more values in the statement. The program is stored in code segment area. The general format is: These are referred to as pseudo-operations or as assembler directives.