How are comparisons done in 8086 assembly language, Computer Engineering

Assignment Help:

Q. How are comparisons done in 8086 assembly language?

There is a compare instruction CMP. Though this instruction just sets the flags on comparing two operands (both 16 bits and 8 bits). Compare instruction just subtracts value of source from destination without storing result however setting the flag at the time of the process. Normally only 3 comparisons are more important. These are:

Result of comparison    Flag(s) affected

Destination < source    Carry flag = 1

Destination = source    Zero flag = 1

Destination > source    Carry = 0, Zero = 0

Let us look at 3 illustration which show how flags are set when numbers are compared. In illustration 1 BL is less than 10 so carry flag is set. In illustration 2 the zero flag is set since both operands are equal. In illustration 3 the destination (BX) is greater than source so both zero and carry flags are clear.

Example 1: 

 MOV BL, 02h 

 CMP BL, 10h; Carry flag = 1

Example 2:

 MOV AX, F0F0h

 MOV DX, F0F0h

 CMP AX, DX; Zero flag = 1

Example 3:

MOV BX, 200H

CMP BX, 0; Zero and Carry flags = 0


Related Discussions:- How are comparisons done in 8086 assembly language

Classify data networks, Classify data networks. Data Network Classifica...

Classify data networks. Data Network Classifications: Data Networks are classified as per to their geographical coverage: - Wide area networks (WANs) - Metropolitan ar

Specifying the problem - learning decision trees, Specifying the Problem: ...

Specifying the Problem: Now next here furtherly we now use to look at how you mentally constructed your decision tree where deciding what to do at the weekend. But if one way

Explain the structure of plasma panel display, a. Explain the meaning of fr...

a. Explain the meaning of frame buffer? Draw a block diagram showing the method for scanning out an image from frame buffer to display surface. b. Explain the structure of plasm

What is preemptive and nonpreemptive scheduling, What is preemptive and non...

What is preemptive and nonpreemptive scheduling? Under nonpreemptive scheduling once the CPU has been allocated to a process, the process keeps the CPU unless it releases the C

What is an interface and what is an abstract class, What is an interface an...

What is an interface and what is an abstract class? Please, expand by examples of using both. Explain why.   In a interface class, all methods are abstract without execution w

Combining goals and design principles, The Set Book assignment should enabl...

The Set Book assignment should enable you to begin talking about the usability of interactive products in terms of a variety of parameters. Instead of simply saying 'nice cell phon

What are pages, What are pages? All programs and date are composed of f...

What are pages? All programs and date are composed of fixed length units known as pages. Each page consists of blocks of words that occupy contiguous locations in main memory

What are user threads, What are User threads   User threads are support...

What are User threads   User threads are supported above the kernel and are executed by a thread library at the user level. Thread creation & scheduling are done in the user sp

What is the main problem with segmentation, What is the main problem with s...

What is the main problem with segmentation? Problem with segmentation (i) Is with paging, such mapping needs two memory references per logical address that slows down the

Interrupt - driven input-output, Q. Interrupt - Driven Input-output? Pr...

Q. Interrupt - Driven Input-output? Problem with programmed I/O is that processor has to wait a long time for I/O interface to see whether a device is free or waits until compl

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd