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

How can i handle floating-point exceptions gracefully, 'On many systems, yo...

'On many systems, you can describe a function matherr which will be known as when there are certain floating-point errors, like errors in the math routines in .

What are program-invisible registers, What are program-invisible registers?...

What are program-invisible registers? Ans: the local and global descriptor tables are found in the memory system. To access and specify the address of these tables, program inv

What is the role of ir and pc, What is the role of IR and PC?  Instruct...

What is the role of IR and PC?  Instruction Register (IR) having the instruction being implemented. Its output is available to the control circuits, which make the timing signa

Programs portable on unix, How do you make programs portable on Unix and Do...

How do you make programs portable on Unix and Does under such circumstances? Constructors are invoked themself when the object is created for a class. There may be any number o

Web designing, how to start a web designing would you please guide me

how to start a web designing would you please guide me

Explain top-down parsing, Explain Top down parsing. Top down parsing...

Explain Top down parsing. Top down parsing: Specified an input string, top down parsing tries to derive a string identical to this by successive application of grammar rule

Give an example of shortest job next scheduling, Consider the following set...

Consider the following set of jobs with their arrival  times, execution time (in minutes), and deadlines. Job Ids Ar r ival Time E xecuti

Explain about interrupt servicing routines, Q. Explain about Interrupt serv...

Q. Explain about Interrupt servicing routines? First the situation is to be checked as to why the interrupt has happened. That includes not only device but also why the device

Translate the sentences into predicate calculus, Translate each of the foll...

Translate each of the following sentences into predicate calculus, conceptual dependencies, and conceptual graphs: 1. Bill sold the book to the book store." 2. "John borrowed

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