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

What is polling, What is polling? Polling is a scheme or an algorithm t...

What is polling? Polling is a scheme or an algorithm to recognize the devices interrupting the processor. Polling is employed when multiple devices interrupt the processor by o

What is language of a model, What is language of a model?   Language of...

What is language of a model?   Language of a model is the collection of formulae that use only the relational symbols the model assign and that use every relation symbol with t

What is visibility give uml notation, What is visibility give UML notation?...

What is visibility give UML notation? Visibility refers to the ability of a process to reference a feature from another class and has possible valued of public, private, protec

First order predicate logic - artificial intelligence, First Order Predicat...

First Order Predicate Logic : This is a more expressive logic because it is mostly builds on propositional logic by allowing us to needs as constants, variables, predicates,

Generate the output that the temperature entered is outside , Write a pseud...

Write a pseudocode for a program that reads a temperature as a whole number from a user and outputs a "probable" season (winter, sprint, summer, or fall) depending on the temperatu

Write heterogeneous functions, Write "heterogeneous" functions If a pro...

Write "heterogeneous" functions If a program uses simulated, dynamically allocated multidimensional arrays, it becomes possible to write "heterogeneous" functions which don't h

Explain conditions under which a deadlock situation arise, What are conditi...

What are conditions under which a deadlock situation may arise? A deadlock situation can arise if the following four conditions hold concurrently in a system:  a. Mutual exc

C++, What are virtual Functions

What are virtual Functions

What is cache coherency, Cache coherence refers to the integrity of data st...

Cache coherence refers to the integrity of data stored in local caches of a shared resource. Cache coherence is a special case of memory coherence. When clients in a system, mainly

Show the decimal representation in computers, Binary number system is most ...

Binary number system is most common for computer due to two stable states of its components. However unfortunately this isn't a very natural system for us as we deal with decimal n

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