Question

Suppose you have the following set of hexadecimal values: $20, $25, $40, $50, $12. Write a segment of program to find the minimum and maximum values of the set. Answer must be written in assembly.

Answer 1

For implementation of given problem we use CMP instruction which compare two operand by subtracting them
                        If Accumulator > Register then carry and zero flags are reset
                        If Accumulator = Register then zero flag is set
                        If Accumulator < Register then carry flag is set

Here List of numbers store from 2000H to 2004H and maximum number is at 2010H and minimum number is at 2011H.

It follow the following step for finding the minimum and maximum number from given number.

1. In B register maximum number is stored and in C register minimum number is stored.

2. Load counter =number of element in D register

3. Load starting element in Accumulator which is 2000h, B and C register

4. Compare Accumulator and B register

5. Transfer contents of Accumulator to B If carry flag is not set else, compare Accumulator with C register, if carry flag is set transfer contents of Accumulator to C

6. Decrement counter in D register

7. If D>0 take next element in Accumulator and go to point 4

8. If D=0, store B to 2010h and C register in memory 2011h

9. End of program

Program:

ADDRESS	LABEL	INSTRUCTION	COMMENT
2000H		LXI H, 2000H	Load starting address of list which is 2000h
2003H		MOV B, M	Store maximum in register B
2004H		MOV C, M	Store minimum in register C
2005H		MVI D, 05H	Counter for 5 elements set register D=5
2007H	LOOP:	MOV A, M	Retrieve list element in Accumulator
2008H		CMP B	Compare element with maximum number
2009H		JC MIN	Jump to MIN if not maximum
200CH		MOV B, A	Transfer contents of A to B as A > B
200DH	MIN:	CMP C	Compare element with minimum number
200EH		JNC SKIP	Jump to SKIP if not minimum
2011H		MOV C, A	Transfer contents of A to C if A < minimum
2012H	SKIP:	INX H	Increment memory to next address which is 2001h
2013H		DCR D	Decrement counter
2014H		JNZ LOOP	Jump to LOOP if D > 0
2017H		LXI H, 2010H	Load address 2010h to store maximum
201AH		MOV M, B	Move maximum to 2010H
201BH		INX H	Increment memory so next address is 2011h
201CH		MOV M, C	Move minimum to 2011H
201DH		HLT	Halt

Output:

If at any point you find any difficulty feel free ask me.