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 are digital signatures and its uses, What are Digital Signatures and i...

What are Digital Signatures and its uses? A digital signature is an electronic quite than a written signature which can be used through someone to authenticate the identity of

What is an advantage of executing a process in background, What is an advan...

What is an advantage of executing a process in background? The most common reason to put a process in the background is to permit you to do something else interactively without

Difference between overlay graph and correlate graph, Overlay Graph: It ove...

Overlay Graph: It overlay the content of two graphs that shares an ordinary x-axis. Left Y-axis on the merged graph show's the present graph's value & Right Y-axis illustrate the v

Describe real and protected mode, Describe Real and protected mode: Op...

Describe Real and protected mode: Operation of Real mode interrupt:   When microprocessor completes executing the current instruction, it concludes whether an interrupt is act

How to create an html document, An HTML document can be created by using an...

An HTML document can be created by using any HTML editor or text editor such as notepad etc. STEPS FOR CREATING A SIMPLE HTMLPROGRAM   1. Go to Start -> Programs->A

C, usability of union

usability of union

Define service (within r/3), Define service (within R/3)? A service is...

Define service (within R/3)? A service is a process or group of processes that perform a exact system function and often give an application-programming interface for other pr

What do you mean by internet, Q. What do you mean by Internet? Ans: In...

Q. What do you mean by Internet? Ans: Internet is a network of networks or collection of networks. Several networks such as WAN and LAN connected through suitable hardware an

Explain the types of computer architecture, Explain the types of computer a...

Explain the types of computer architecture Computer architecture can be divided into three main categories: Instruction Set Architecture, or ISA, is the image of a computing

What is applying of an open source systems, What is applying of an Open Sou...

What is applying of an Open Source Systems?   No licensing issues No initial cost Speed of Access Openness and Transparency

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