Sub subtract instruction, Electrical Engineering

SUB Subtract Instruction

This  instruction  is used to  subtract the contents of any  register  or memory location from  the contents of  accumulator. There are two  formats as follows:

a.Subtract the contents of Register The  contents of  register R are subtracted  from the contents of accumulator and  result of operation is  stored in the accumulator. Here register R  may be any  one  of the A, B, C,D, E,H or L registers.

SUBR                   ( A- A - R)

Flags : All  flags  are modified according to the results.

As we have already  discussed in chapter 1 that the subtraction is done  using 2 s  complement  method in microprocessor.  Followings  steps are followed  by the  8085 microprocessor while performing  subtract operations.

 Step1.  Converts subtrahend ( the  number to  be subtracted) into its 1 s complement form.

 Steps2.  Adds 1 to  the 1 complements  form to  obtain 2  complement  form the  subtrahend.

 Step3.  Adds 2 complements  to the minuend ( the  contents of the accumulator).

 Step 4.  Complements  the carry  flag.

Posted Date: 4/4/2013 7:06:46 AM | Location : United States







Related Discussions:- Sub subtract instruction, Assignment Help, Ask Question on Sub subtract instruction, Get Answer, Expert's Help, Sub subtract instruction Discussions

Write discussion on Sub subtract instruction
Your posts are moderated
Related Questions
What is TPA (transient program area)? The memory system is divided in three major parts: transient program area, System is and XMS that is extended memory system.

Uninterruptable power  Supply An uninterruptible  power supply  provides emergency power when  utility power  is not  available. It  maintains the supply  under  all condition

how started the use of complex variables in circuit analysis for the first time.

Consider a transmitter S which radiates a sinusoidal carrier frequency of 1850 MHz. For a vehicle moving at 26.82 m/s, compute the received carrier frequency if the vehicle is movi

Question : a) State six desirable requirements of a generic photo-detector. b) A gallium arsenide pin photo-diode has an intrinsic layer of width 1 μm. The diode is revers

Q. Describe about Boltzmann constant? The constant η in Figure (b) stands for the noise power spectral density, expressed in terms of power per unit frequency (W/Hz). Statistic

The winch uses a 415 Volt 50 Hz AC motor, so both the up/down and run/stop controls actually operate +24V relays, whose contacts switch the 415Vac to the winch. The relays also pro

Q. Discuss the operation of a transistorized phase shift oscillator with the help of a diagram? Explain the phase shifting circuit? An oscillator is a circuit which converts elec

Q.   List and explain the factors involved in the voltage build up of shunt generator. Ans. following factors are involved in voltage build up of shunt generation

Build an intersection traffic light using the LED's as in the diagram below Day Use the LED's on the trainer (port 11) Main Street and Side Street alternate. Mai