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 the difference between proc. sent by val and by ref, What is the di...

What is the difference between proc. sent BY VAL and By Ref? BY VAL: Alters will not be reflected back to the variable. By REF: Alters will be reflected back to that variab

Microprocesser, explain the bock and pin diagram of 8259 micropocesser

explain the bock and pin diagram of 8259 micropocesser

What are the necessary elements of an e-banking site, What are the necessar...

What are the necessary elements of an e-banking site? E-banking systems rely upon a number of common elements or processes. The given list comprises many of the potential elem

Determine the output of an even parity generator, When the set of input dat...

When the set of input data to an even parity generator is 0111, the output will be ? Ans. Into even parity generator if number of one is odd then output will be 0.

IEEE802.4 Token Bus Network, en a five station token bus LAN with station a...

en a five station token bus LAN with station addresses of 3000, 500, 100, 70, and 50. Stations with addresses of 5000, 4000, 400, 90, and 60 are waiting to enter the ring. Assume a

What are modes of operation of centralized spc, What are modes of operation...

What are modes of operation of centralized SPC? In about all the present day electronic switching systems utilizing centralized control, only a two-processor configuration is

Name the two operations of stack, Name the two operations of stack A st...

Name the two operations of stack A stack has only two operations and they are insertion and deletion of items. The operation insertion is called push (or push-down) as it can b

Programming with loops and comparisons, Q. Programming with loops and compa...

Q. Programming with loops and comparisons? This segment deals with more practical illustrations employing comparison, loops and shift instructions. Simple Program Loops

Performance and issues in pipelining-speedup, Performance and Issues in Pip...

Performance and Issues in Pipelining Speedup:   Firstly, we get the speedup factor that is we see how much speed up performance we get through pipelining. First we get the

Explain ip address structure, Q. Explain IP Address Structure? Internet...

Q. Explain IP Address Structure? Internet addresses are divided in five types of classes. Classes were designated A through E. class A address space enables a small number of 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