Describe program control instructions, Computer Engineering

Assignment Help:

Q. Describe Program Control Instructions?

These instructions specify conditions for altering the sequence of program execution or we can say in other words that the content of PC (program counter) register.  PC points to memory location which holds the subsequent instruction to be executed. The alteration in value of PC as a result of execution of control instruction such as BRANCH or JUMP causes a break in sequential execution of instructions. The most common control instructions are as following:

JUMP and BRANCH may be unconditional or conditional. JUMP is an unconditional branch used to implement simple loops. JNE jump not equal is conditional branch instruction. The conditional branch instructions like BRP X and BRN X causes a branch to memory location X if the result of most recent operation is positive or negative correspondingly. If the condition is true PC is loaded with branch address X and next instruction is taken from X otherwise PC is not changed and the subsequent instruction is taken from location pointed by PC. Figure below displays an unconditional branch instruction and a conditional branch instruction if content of AC is zero.

MBR←0; Assign 0 to MBR register

X←2001; Assume X to be an address location 2001

READ X; Read a value from memory location 2001 into AC

BRZ 1007; Branch to location 1007 if AC is zero (Conditional branch on zero)

ADD MBR; add the content of MBR to AC and store result to AC

TRAS MBR; Transfer the contents of AC to MBR 

INC X; Increment X to point to next location 

JUMP 1001;Loop back for further processing.


Related Discussions:- Describe program control instructions

Unix for multiprocessor system, The UNIX operating system for a multiproces...

The UNIX operating system for a multiprocessor system has a number of extra features as compared to normal UNIX operating system.  Let's first consider the design objectives of mul

Subtract two number by using 1's complement, Subtract the given number usin...

Subtract the given number using 1's complement 11011 - 11001 Ans. 11011 - 11001 = X - Y                             X =    11011  1's complement of Y =    00110

How many lists can a program can produce, How many lists can a program can ...

How many lists can a program can produce? Every program can produce up to 21 lists: one basic list and 20 secondary lists.  If the user makes a list on the next level (that is,

Contraposition, Contraposition : The contraposition equivalence is as ...

Contraposition : The contraposition equivalence is as follows:  So it may seem a small strange at first, this means that it appears which we have said nothing in the f

Internal organisation of memory chips, expplain in detail the internal orga...

expplain in detail the internal organisation of computer?

Objectives-interconnection network, Objectives After examining this uni...

Objectives After examining this unit, learner's will be able to understand discuss the importance and needs of interconnection network; explain the part of interconn

Show the connection between different networks, Q. Show the Connection betw...

Q. Show the Connection between different networks? The connection between different stages is made in following manner:  all outputs of 1 st crossbar switch of first stage a

Define restoring method, Define restoring method? The hardware method j...

Define restoring method? The hardware method just explained is called the restoring method. The reason for this name is that the partial reminder is restored by adding the divi

Messagebox with the message, We have to make an application that will dynam...

We have to make an application that will dynamically add a menu strip with menu items to a form(ie NOT dragged and dropped onto the form) in Visual Basic. The menu strip should be

Unity - variety - principles of composition, Unity / variety Unity is ...

Unity / variety Unity is created by the use of elements that look like they belong together, in other words the piece will have a feeling of internal  consistency. The most

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