Assembly language program to find largest number in an array

Problem – Determine largest number in an array of n elements. Value of n is stored at address 2050 and array starts from address 2051. Result is stored at address 3050. Starting address of program is taken as 2000. 

Example:

Algorithm:

1. We are taking first element of array in A
2. Comparing A with other elements of array, if A is smaller then store that element in A otherwise compare with next element
3. The value of A is the answer

Program:

Memory Address	Mnemonics	Comment
2000	LXI H 2050	H←20, L←50
2003	MOV C, M	C←M
2004	DCR C	C←C-01
2005	INX H	HL←HL+0001
2006	MOV A, M	A←M
2007	INX H	HL←HL+0001
2008	CMP M	A-M
2009	JNC 200D	If Carry Flag=0, goto 200D
200C	MOV A, M	A←M
200D	DCR C	C←C-1
200E	JNZ 2007	If Zero Flag=0, goto 2007
2011	STA 3050	A→3050
2014	HLT

Explanation:

 Registers used: A, H, L, C

1. LXI 2050 assigns 20 to H and 50 to L
2. MOV C, M copies content of memory (specified by HL register pair) to C (this is used as a counter)
3. DCR C decrements value of C by 1
4. INX H increases value of HL by 1. This is done to visit next memory location
5. MOV A, M copies content of memory (specified by HL register pair) to A
6. INX H increases value of HL by 1. This is done to visit next memory location
7. CMP M compares A and M by subtracting M from A. Carry flag and sign flag becomes set if A-M is negative
8. JNC 200D jumps program counter to 200D if carry flag = 0
9. MOV A, M copies content of memory (specified by HL register pair) to A
10. DCR C decrements value of C by 1
11. JNZ 2007 jumps program counter to 2007 if zero flag = 0
12. STA 3050 stores value of A at 3050 memory location
13. HLT stops executing the program and halts any further execution

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