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 a message in mqseries, A message is a string of bytes that has mean...

A message is a string of bytes that has meaning to the applications that use it Message = Header(s) + Application Data A message having of a header and the attached applicat

Explain the major consideration of laptop computers, Explain the major cons...

Explain the major consideration of laptop One of the major considerations when buying a laptop is battery life. This can rely on a number of things though one major factor is p

What is the fundamental digital design, What is the fundamental Digital Des...

What is the fundamental Digital Design? Digital design is distinct through analog design. In analog circuits we deal along with physical signals that are continuous in amplitud

Explain sequential sharing, Explain Sequential Sharing In this sharing ...

Explain Sequential Sharing In this sharing method, a file can be shared by just one program at a time, i.e. file accesses by P1 and P2 are spaced out over time. A lock field ca

How would you implement inheritance using vb.net/c#, How would you implemen...

How would you implement inheritance using VB.NET/C#? When we set out to execute a class using inheritance, we must first start with an existing class from which we will derive

Demultiplexers, Explain briefly about demultiplexers?

Explain briefly about demultiplexers?

Can we call reports from interactive reporting lists, Can we call reports ...

Can we call reports and transactions from interactive reporting lists? Yes.  It also permits you to call transactions or other reports from lists.  These programs then use val

Explain about the data logging, Data logging  This technique involves ...

Data logging  This technique involves collecting data automatically using sensors; frequently used when doing scientific experiments or monitoring a system.

Difference between next and continue clause, The difference among the next ...

The difference among the next and continue verb is that in the continue verb it is used for a situation where there is no EOF condition that is the records are to be accessed again

What are two reasons for using layered protocol, What are two reasons for u...

What are two reasons for using layered protocol? Layered protocol implies protocols used into each layer are the layer's own business that is they don't influence protocol of a

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