September 28, 2011
Aim: Write an ALP to find largest element in a given array present in external memory with a starting address 4000H and size of an array is 05H and store the largest number at external memory 4500H.
Apparatus Used: Micro-controller kit.
Assumption: Five numbers stored in memory locations starting from 4000H. We have to find largest number and stored that number at 4500H.
Algorithm:
1. Load the R0 register with length of the array.
2. Initialize a Register B to store output.
3. Load DPTR with memory location 4000H.
4. Get first element into the Accumulator.
5.Compare A and B. If A is less than B then jump to Next Number. If A is greater than B then move the that number (Accumulator) into B and get Next Number.
6. Decrement the R0 register each time by 1 for every data taken from the array.
7. Repeat the process till counter is reset.
8. Finally move the content of B into Register A and store largest number at 4500H.
Program:
Description of used instruction:
MOV: Used for Load and Copy the Data. This copies a byte from the source location to destination.
DJNZ: In this instruction a byte is decremented, and if result is not zero it will jump to the target address.
MOVX: This instruction transfer data between external memory and register A.
DPTR: This is Data Pointer. It is used for containing 16 bit data or memory address.
SJMP: Short Jump loop is used for indefinite loop within program basically used to end the program.
INC: This instruction adds 1 to the register or memory location specified by the operand.
0F0: These are Special Function Register address. These are used to store the address of register B.
CJNE : Compare and Jump if not equal to at a given location.
Result:
Input: 4000-09
4001-02
4002-07
4003-04
4004-05
Output: 4500-09
Procedure to look output:
· After ending (SJMP) the program, press Enter two times.
· You will get message “Welcome to ------KIT”.
· Press G and Provide initial address of program as in this program, starting address is 3000 H.
· Press Enter.
· After pressing Enter, You will get Message “Execution Completed”.
· Press Reset on micro-controller KIT.
· Press M and You will get Message “Enter Address”.
· Provide Location of Input as in this program 4000H. Press Space and write a first number and Press Space and provide second number and so on.
· Press Enter two times again.
· Press G and provide starting address and Press Enter.
· You will Get Message “Execution Completed”.
· Press M and You will Get Message “Enter Address”.
· Provide Address for Output as in this Program 4500H and Press Space and you get Output and so on.
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