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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