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 prefetch instructions, What are prefetch instructions? Prefetc...

What are prefetch instructions? Prefetch instructions are those instructions which can be inserted into a program either by the programmer or by the compiler.

Digital logic, write a short note on the tri state ttl inverter

write a short note on the tri state ttl inverter

What is the system call available to change the personality, What is the sy...

What is the system call available to change the personality? The system call personality prefers to a method to modify its implementation domain in order that Linux can emulate

Logic calculations are done in which type of registers, Accumulator is the ...

Accumulator is the register in which Arithmetic and Logic calculations are completed.

Discuss the advantages of firewalls, Discuss the advantages of Firewalls ...

Discuss the advantages of Firewalls Firewalls also offer additional protection to local users who like to browse or surf out from the Intranet to the Internet, by acting as pro

What layers are covered under end to end layer connectivity, What layers ar...

What layers are covered under end to end layer connectivity? The layers 4 to 7 of ISO-OSI reference model communicate along with peer entities into the end systems. There is n

Address phase timing - computer architecture, Address phase timing: On...

Address phase timing: On the rising edge of clock 0, the initiator notes IRDY # and FRAME# both high, and GNT# low, so it drives the command, address and asserts FRAME# in tim

Components of flash, A piece of art can be looked at as having 3 main compo...

A piece of art can be looked at as having 3 main components, the subject, the composition and the content. Subject The subject of an artwork is, in simple terms, the object

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