Conditional Codes
The condition code flags are used to store the results of certain condition when certain operation are performed during execution of the program.
The condition code flags are stored in the status registers. The status register is also referred is also referred to as flag register. ALU operations and certain register operations may set or reset one or more bits in the status register. Status bits lead to a new set of microprocessor instructions. These instructions permit the execution of a program to change flow on the basis of the condition of bits in the status register. So the condition bits in the status register can be used to take logical decisions within the program. Some of the common condition code flags are:
- Carry/Borrow : The carry bit is set when the summation of two 8-bit numbers is greater than 1111 1111(FFH). A borrow is generated when a large number is subtracted from a smaller number.
- Zero : The zero bit is set when the contents of register are zero after any operation. This happens not only when you decrement the register, but also when any arithmetic or logic operation causes the contents of register to be zero.
- Negative or sign : In 2's compliment arithmetic, the most significant bit is a sign bit. If this bit is logic 1, the number is negative number, otherwise a positive number. The negative bit or sign bit is set when any arithmetic or logical operation gives a negative result.
- Auxiliary carry : The auxiliary carry bit of status register is set when an addition in the first four bits causes a carry into the 5th bit. This is often referred as half carry or intermediate carry. This is used in the BCD arithmetic.
- Overflow flag : In 2's complement arithmetic, most significant bit is used to represent sign and remaining bits are used to represent magnitude of a number. This flag is set if the result of a signed operation is too large to fit in the number of bits available to represent it.
- Parity : When the result of an operation leave the indicated register with an even number of 1's, parity bit is set.
Light Emitting Diode(LED)
Working Principle
Applications Of LED
The LED is a PN junction diode which emits light when an electric current passes through it in the forward direction.
A PN junction can convert the absorbed light energy into electric current. Now if we reverse the same process that is the pn junction emits light when electric energy is applied to it.
This phenomenon is generally called electroluminescene. Electroluminescene is a property of the material to convert electrical energy into light energy.
Construction
The semiconductor layer of p-type is placed above n-type because the charge carrier recombination occurs in p-type. Besides, it is the surface of the device, thus the light emitted can be easily seen on the surface. If p-type is placed below the light will be emitted from the surface of p-type but we will not be able to see it. This is the reason that p-type is placed above. The below figure shows the cross sectional view of diffused LED.
The p-type layer is formed from diffusion of semiconductor material. On the other side in n-type region, the layer is grown on n-type substrate. The mental film is used on the p-type layerr to provide anode connection to the diode.
The significance of gold-film layer, gold film layer on n-type also provide reflection from the bottom surface of the diode. If any significance part of radiated light tends to hit bottom surface then that will be reflected from the bottom surface to the device top surface. This increases LED's efficiency.
Working Principle
The charge carriers recombine in a forward biased p-n junction as the electrons cross from the n region and recombine with the holes existing in the p-region. Free electrons are in the conduction band of the energy levels, while holes are in the valence energy band. Thus the energy level of the holes is less than the energy levels of the electrons. Some portion must be dissipated to recombine the electrons and the holes. The energy is emitted in the form of heat and light.
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| Working Of LED |
The working of LED depends on the quantum theory. The quantum theory states that when the energy of electrons decreases from the higher level to lower level, it emits energy in the form of photons. The energy of the photos is equal to the gap between the higher and lower level as shown above.
The LED is connected in the forward biased, which allows the current to flows in the forward direction. The flow of current is because of the movement of the electrons in the opposite direction. The recombination shows that the electrons move from the conduction band to valence band and they emits electromagnetic energy in the form of photons. The energy of photons is equal to the gap between the valence and the conduction band. Color of light was determined by the band gap of semiconductor material.
Application
- They are used in remote control systems such as TV or LCD remote.
- Used in electronic calculators for showing the digital data.
- Used in traffic signals for controlling the traffic crowds in cities.
- Used in digital computers for displaying the computer data.
- Used in digital watches and automotive heat lamps.
Purpose Of Embedded Systems
Data Connection, storage and representation
- Purpose of embedded system design is data collection. It performs acquisition of data from the external world.
- Data collection is usually done for storage, analysis, manipulation and transmission.
- Data can be analog and digital.
- Analog is directly connected from the analog signal. There is no need to convert data.
- The embedded systems which have data capturing techniques collects data directly in the form of analog signals whereas embedded systems with digital data collection mechanism convert the analog signal to the digital signal using analog to digital converters.
- Digital camera is an example of embedded systems
Data Communication
- Embedded data communication systems are in home networking systems to complex.
- Data transmission is in the form of wire medium or wireless medium. Data can either be transmitted by analog means or by digital means.
- Bluetooth, ZigBee and Wifi is an example of wireless communication and USB, TCP/IP is an example of wired communication.
- Network hubs, routers, switches are example of dedicated data transmission embedded systems.
Data Processing
- Embedded systems with signals processing functionalities are employed in application demanding signals processing like speech coding, audio video codec, transmission application etc..
- A digital hearing aid is a typical example of data processing
- Digital hearing aid improves the hearing capacity of hearing impairment person.
Monitoring
- Medical domain embedded products come under monitoring function. Patient heartbeat is monitored by electro cardiogram machine but it cannot impose control over the heartbeat.
- Digital CRO, digital multi-meters and logic analyzers are the example of monitoring embedded devices.
Control
- In embedded system, sensor and actuators are used for controlling the system. Sensor are connected to input port. Actuators are connected to output port.
- Sensor captures the changes in the environment variable. Middle system process information. Actuators are changed according to the input variable. It display the output.
- Example of control is air conditioners systems. It control the room temperature to a specific limit.
Thank You
Embedded Systems and its classification.
Embedded systems
Characteristics Of embedded systems
Classification Of embedded systems based on generation
Let's Begin..
Definition : Embedded systems are computing systems with tightly coupled hardware and software integration that are designed to perform a dedicated function.
Embedded systems cover a large range of computer systems from ultra small computer based devices to large systems monitoring and controlling complex processes.
In most of the cases embedded systems are real-time systems. In many cases embedded systems are safety or mission critical systems.
Real-time systems are those systems in which the overall correctness of the system depends on both the functional correctness and timing correctness. Real-time systems also have a substantial knowledge of the system it controls and the applications running on it. These are deadline dependent.
Characteristics Of Embedded Systems
- It has limited memory and limited number of peripherals.
- They need to be highly reliable and stable.
- It should be small set of function.
- Typically designed for a specific purpose.
- Safety, security, real-time, power consumption.
Classification Of Embedded Systems
- First Generation computers
The early embedded systems were built around 8 bits microprocessors like 8085 and z80 and 4 bits microcontrollers. Simple in hardware circuits with firmware development in assembly code.
Ex: Telephone keypads, stepped motor control units etc.
- Second Generation computers
They are embedded systems built around 16 bit microprocessor and 32 bit microcontroller following the first generation embedded systems. The instruction set of the second generation is complex and powerful.
Ex: Data Acquistion systems, SCADA systems, etc..
- Third Generation computers
Embedded systems developers started making use of powerful 32 bit processor and 16 bit controller for their design. A new concept of application and domain specific processor/controllers like digital signal processors (DSP) and application specific integrated circuits(ASICs) came into the picture. The instruction set of processors become more complex and powerful.
Ex: Intel pentium, Motorola 68k.
- Fourth Generation computers
The advent of systems on chips(SOC), reconfigurable processors and multicore processors are bringing high performance tight integration and miniaturisation into the embedded device market. The SOC technique implement a total system on a chip by integrating different functionalities with a processor core on an integrated circuit.
Types of network
Characteristic of networking
Types of connection
Network criteria
Network
Network is a set of devices connected by communication links.
Load can be a computer printer, or or any other device capable of
sending and slash or receiving data generated by other Nodes on
the network.
Load can be a computer printer, or or any other device capable of
sending and slash or receiving data generated by other Nodes on
the network.
Network criteria
A network must be able to meet a certain number of criteria.
The most important of these are are
performance, reliability and security.
The most important of these are are
performance, reliability and security.
Performance
Performance can be measured in many ways,Including transit time
and response time.
and response time.
transit time is the amount of time required for a message to travel
from one device to another.
from one device to another.
response time is the elapsed time between an enquiry and response.
Performance of a network depends on a number of factors including
number of users the type of transmission medium, the capability of
connected hardware, and the efficiency of the software.
number of users the type of transmission medium, the capability of
connected hardware, and the efficiency of the software.
Performance is often evaluated by to networking metrics :
throughput and delay.
throughput and delay.
we often need more throughput and Less delay.
Reliability
In addition to accuracy of delivery, network reliability is measured by the frequency of failure, the time it takes a link to recover from a failure, the network robustness in catastrophe.
Security
Network security issues includes protecting data from unauthorised access, protecting data from damage and development, and implementing policies and procedure for recovery from breaches and at a losses.
Types of connection
A network is two or more devices connected through links.
A link a is a communication pathway that transfer data from one
device to another. For visualising for princess it is simplest to
imagine any link as a line drawn between two points.
For communication to occur, two devices must be connected in some
way to the same link at the same time .
A link a is a communication pathway that transfer data from one
device to another. For visualising for princess it is simplest to
imagine any link as a line drawn between two points.
For communication to occur, two devices must be connected in some
way to the same link at the same time .
There are two possible types of connections:
point to point and multipoint.
point to point and multipoint.
Point to point
A point to point connection provides a dedicated link between two
devices. The entire capacity of the link is is reserved for transmission
between those two devices. Most point to point connection use an
actual length of wire or cable to connect the two ends.
devices. The entire capacity of the link is is reserved for transmission
between those two devices. Most point to point connection use an
actual length of wire or cable to connect the two ends.
When you change television channels by remote control,
you establishing point to point connection between the remote control
and the television control system.
you establishing point to point connection between the remote control
and the television control system.
Multipoint
A multipoint connection is one in which more than two specific
devices share a single link.
devices share a single link.
In a multipoint environment, the capacity of the channel is shared,
either spatially or temporally.
If several devices can use the link simultaneously, it is a spatially
shared connection.
If uses must take turns, it is a time shared connection.
either spatially or temporally.
If several devices can use the link simultaneously, it is a spatially
shared connection.
If uses must take turns, it is a time shared connection.
Operating System(OS)
What is OS
Goals of OS
Views of OS
Today we will be learning about OS
OPERATING SYSTEM
An OS is a program that acts as an intermediate between computer users and computer hardware.
It also provides basis for application program.
Goals of OS
What is OS
Goals of OS
Views of OS
Today we will be learning about OS
OPERATING SYSTEM
An OS is a program that acts as an intermediate between computer users and computer hardware.
It also provides basis for application program.
Goals of OS
- To execute programs.
- To solve user problems easily.
- To make the computer easy to use.
Hardware provides basic computing resources
- CPU
- Memory
- I/O devices
Application program defines how the resources are used to solve computing problems of the user.
Ex: work process, spread sheet, compilers.
The OS control and coordinates the use of hardware among various application program for various users.
There are two OS views
- User view
- System view
User view
• Most users use a PC consisting of a monitor, keyboard and system unit.
The OS is designed mostly for ease of use.
-Some attention is given to the performance.
-No attention given to resource utilisation.
-The OS is optimised for the single user experience.
• Some users use a terminal connected to a mainframe or minicomputer
-OS is designed to maximize resource utilisation and to assure that no individual user takes more than his/her fair share.
• Some users use a workstation connected to network
-The users have dedicated resources such as networking and services.
-The OS is designed to compromise between
-individual usability
-resource utilisation
• Some users use a handheld computer
- the OS is designed mostly for individual usability.
-performance per unit of battery life is a very important factor.
System Views
• An OS as a resource allocate
- Resources used to solve a computing problem, CPU time, memory space, file storage space, I/O devices.
- OS manages and allocates the above resources to programs and the users.
• An OS is a control program
- OS is needed to control.
- operation of I/O devices.
- execution of user programs to prevent errors.
Components Of Data Communication
Data Communication VTU NOTES
Data Communication system
Data Communication concepts
Data Communication definition
It's been a long time seen I have post.
Today we will be learning about components of Data Communication.
A data communications system has five components:
Message:The message is the information (data) to be communicated. Popular forms of information include text,numbers, pictures, audio, and video.
Sender:The sender is the device that sends the data message.It can be a computer,workstation, telephone handset, video camera, and so on.
Receiver: The receiver is the device that receives the message. It can be a computer,workstation, telephone handset, television, and so on.
Transmission medium: The transmission medium is the physical path by which a message travels from sender to receiver. Some examples of transmission media include twisted-pair wire,coaxial cable, fiber-optic cable, and radio waves.
Protocol: A protocol is a set of rules that govern data communications. It represents an agreement between the communicating devices. Without a protocol, two devices may be connected but not communicating.
Data Representation
Information today comes in different forms such as text, numbers, images, audio, and video.
Text: In data communications, text is represented as a bit pattern, a sequence of bits (0s or 1s).Different sets of bit patterns have been designed to represent text symbols. Each set is called a code, and the process of representing symbols is called coding. Today, the prevalent coding system is called Unicode, which uses 32 bits to represent a symbol or character used in any language in the world.
Numbers: Numbers are also represented by bit patterns.However, a code such as ASCII is not used to represent numbers; the number is directly converted to a binary number to simplify mathematical
operations.
Images: Images are also represented by bit patterns. In its simplest form, an image is composed of a matrix of pixels (picture elements), where each pixel is a small dot. The size of the pixel depends on the resolution. For example, an image can be divided into 1000 pixels or 10,000 pixels. In the second case, there is a better representation of the image (better resolution), but more memory is needed to store the image.
After an image is divided into pixels, each pixel is assigned a bit pattern. The size and the value of the pattern depend on the image. For an image made of only black- and-white dots
(e.g.,a chessboard), a 1-bit pattern is enough to represent a pixel.
There are several methods to represent color images. One method is called RGB, so called because each color is made of a combination of three primary colors: red, green, and blue.
Audio: Audio refers to the recording or broadcasting of sound or music. Audio is by nature different from text, numbers, or images. It is continuous, not discrete. Even when we use a microphone to
change voice or music to an electric signal, we create a continuous signal.
Video: Video refers to the recording or broadcasting of a picture or movie. Video can either be produced as a continuous entity (e.g., by a TV camera), or it can be a combination of images, each a discrete entity, arranged to convey the idea of motion.
May be this was helpful😊
Introduction To Data Communication
Data Communication conceptData Communication system
Data Communication VTU NOTES
Hi everyone!
Today we will learn about Data Communication
Data communication is the exchange of data between two devices via some form of transmission medium such as a wire cable.
For data communications to occur, the communicating devices must be part of a communication system made up of a combination of hardware (physical equipment) and software (programs). The effectiveness of a data communications system depends on four fundamental characteristics: delivery, accuracy,timeliness, and jitter.
- Delivery: The system must deliver data to the correct destination. Data must be received by the intended device or user and only by that device or user.
- Accuracy: The system must deliver the data accurately. Data that have been altered in transmission and left uncorrected are unusable.
- Timeliness: The system must deliver data in a timely manner. Data delivered late are useless.In the case of video and audio, timely delivery means delivering data as they are produced, in thesame order that they are produced, and without significant delay. This kind of delivery is calledreal-time transmission.
- Jitter: Jitter refers to the variation in the packet arrival time. It is the uneven delay in the delivery of audio or video packets. For example, let us assume that video packets are sent every30 ms. If some of the packets arrive with 30-ms delay and others with 40-ms delay, an unevenquality in the video is the result.
Hello everyone!
Its been a very long time since I post!
So today we will be learning about basic instruction cycle, single bus organization of processor.
Lets begin with the topic!
Before going to discuss design approaches for processor unit we first get familiar with the functions of it. The primary function of a processor unit is to execute sequence of instructions stored in a memory, which is external to the processor unit. The sequence of operations involved in processing an instruction constitutes an instruction cycle, which can be subdivided into three major phases:
Fetch cycle, decode cycle and execute cycle.
This is illustrated as shown below
To perform fetch, decode and execute cycles the processor unit has to perform set of operations called micro operations.
The following fig shows the single bus organization of processor unit. It shows how the building blocks of processor unit are organised and how they are interconnected. They can be organized in a variety of ways.
The fig below shows one organization, in which the arithmetic and logic unit and all processor registers are connected through a single common bus. It also shows the external memory bus connected to memory address(MAR) and data register(MDR).
The registers Y,Z and temp in fig are used only by the CPU unit for temporary storage during the execution of some instructions. These registers are never used for storing data generated by one instruction for later use by another instruction. The programmer can not access these registers. The IR and the instruction decoder are integral parts of the control circuitry in the CPU unit. All other registers and the ALU are used for storing and manipulating data. The data registers, ALU and the interconnecting bus is referred to as data path.
Its been a very long time since I post!
So today we will be learning about basic instruction cycle, single bus organization of processor.
Lets begin with the topic!
Before going to discuss design approaches for processor unit we first get familiar with the functions of it. The primary function of a processor unit is to execute sequence of instructions stored in a memory, which is external to the processor unit. The sequence of operations involved in processing an instruction constitutes an instruction cycle, which can be subdivided into three major phases:
Fetch cycle, decode cycle and execute cycle.
This is illustrated as shown below
The following fig shows the single bus organization of processor unit. It shows how the building blocks of processor unit are organised and how they are interconnected. They can be organized in a variety of ways.
The fig below shows one organization, in which the arithmetic and logic unit and all processor registers are connected through a single common bus. It also shows the external memory bus connected to memory address(MAR) and data register(MDR).
The registers Y,Z and temp in fig are used only by the CPU unit for temporary storage during the execution of some instructions. These registers are never used for storing data generated by one instruction for later use by another instruction. The programmer can not access these registers. The IR and the instruction decoder are integral parts of the control circuitry in the CPU unit. All other registers and the ALU are used for storing and manipulating data. The data registers, ALU and the interconnecting bus is referred to as data path.
Voltage Divider Bias Circuit
Voltage Divider Bias Circuit designVoltage Divider Bias Circuit theory
Working of Voltage Divider Bias Circuit
Circuit of Voltage Divider Bias Circuit
Hi everyone!
Today we are going to study about voltage divider bias circuit.
Circuit operation
Voltage divider bias also known as emitter circuit bias. It is the most stable of the three basic transistor biasing circuits. A voltage divider bias circuit is shown in fig and the current voltage conditions through out the discussion are illustrated in fig. It is seen that there is an emitter resistor Re connected in series with emitter, so that the total dc load in series with the transistor is (Rc+Re) and this resistance must be used when drawing the dc load line for the Circuit. Resistor R1 and R2 constitute a voltage Vb. Voltage divider bias circuit are normally designed to have the voltage divider current very much larger than the transistor base current (Ib). In this circumstance, Vbe is larger affected by Ib, so Vbe can be assumed to remain constant.
Referring to fig with Vb constant, the voltage across the emitter resistor is also a constant quantity. This means that the emitter current is constant, the collector current is approx equal to the emitter current is constant.
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The collector current is approx equal to the emitter current so Ic is held at constant level. Again referring to the fig, the transistor collector to emitter voltage is Vce= Vcc-(Ic+Ib)Rc
Clearly, with Ic and Ie constant the transistor collector emitter voltage remains at a constant level.
******
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Zener diode
Zener diode as a voltage regulator
Zener diode working
Zener diode circuit
Zener diode difination
Everyone this is my new post!
And the topic for today is Zener diode as voltage regulator.
We will learning the concept of avalanche breakdown and Zener breakdown
Lets start with the topic
Diodes which have adequate power dissipation capabilities to operate in the breakdown region are commonly called zener diodes.
Avalanche multiplication and zener breakdown are two process, which produce the breakdown region in the reverse bias.
Avalanche Multiplication
During reverse bias the depletion region widens in ordinary diode. Carriers which are generated thermally will get sufficient energy from applied potential. The crystal atom are collided by these carriers and imparts energy to disturb the covalent bond. Because of these actions a new electron hole pair is generated and these electrons also gets energy from applied field. Through continues collision by these electron with another atom more number of electron hole pair is generated. This action continuous and produce additional carriers. This cumulative process is known as avalanche multiplication. This results in large reverse current and diode will be in breakdown region.
Zener breakdown
When a diode is heavily doped, there will be a narrow depletion layer due to this the electric field across depletion layer will be very high. Because of the presence of this electric field across the junction a strong force may be applied on bound electrons by the field to tear it from covalent bonding. The new hole pair created raises the reverse current. This process is known as zener breakdown
Zener diode
A heavily doped diode, which has a sharp breakdown voltage is known as a zener diode. Fig shows the symbol of zener diode.
symbol
Due to heavy doping the electric field in the junction increases during reverse bias. Hence covalent bonds breaks producing a large number of electron hole combinations. This in turn increases reverse current. The diode possess some resistance called zener dynamic resistance.
Thank you. Hope Y'all like it😊
Due to heavy doping the electric field in the junction increases during reverse bias. Hence covalent bonds breaks producing a large number of electron hole combinations. This in turn increases reverse current. The diode possess some resistance called zener dynamic resistance.
Thank you. Hope Y'all like it😊
Light Emitting Diode
Light Emitting Diode definition
Light Emitting Diode working
Light Emitting Diode circuit diagram
Light Emitting Diode applications
Good Morning everyone!
Today we will be learning about LED and its working.
Lets start with the topic
Light Emitting Diode
The LED is a PN- junction diode which emits light when an electric current passes through it in forward direction.
A PN junction can convert absorbed light energy into a proportional electric current. The same process is reversed herre. This phenomenon is generally called electroluminescence. Electroluminescene is the property of the material to converrt electric energy into light energy and later it radiates this light energy.
Working Principle
The charge carriers recombine in a forward biased PN junction as the electrons cross from the N region and recombine with the holes existing in the P region. Free electrons are in the conduction band of energy levels, while holes are in the valence energy band. Thus the energy level of the holes is less than the electrons. Some portion of the energy must be dissipated to recombine the electrons and holes. This energy is emitted in the form of the heat and light.
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Fig
The LED is connected in the forward biased, which allows the current to flows in the forward direction. The flow of current is because of the movement of electrons in the opposite direction. The recombination shows that the electrons move from the conduction band to valence band and they emits electromagnetic energy in the form of photons. The energy of photons is equal to the gap between the valence and the conduction band. Color of light was determined by the band gap of semiconduction or material.
Applications
- There are used in remote control systems such TV or LCD remote.
- Used in electronic calculators for showing the digital data.
- Used in traffic signals for controlling the traffic crowds in cities.
- Used in digital computer for displaying the computer data.
- Used in digital watches and automotive heat lamps.
Photocoupler
Photocoupler working
optocoupler working
Photocoupler construction
Photocoupler circuit diagram
Photocoupler applications
Hello everyone!
Photocoupler working
optocoupler working
Photocoupler construction
Photocoupler circuit diagram
Photocoupler applications
Hello everyone!
My new post is about photocoupler or optocoupler
We will be discussing about construction, working principle and its application of a photocoupler.
Photocoupler
Photocoupler is a component that transfers electrical signals between two isolated circuits by using light.
Photocoupler or optocouplers are used to provide many functions they can be used to link data across two circuits, they can be used within optical encoders, where the optocoupler provides a means of detecting visible edge transitions on an encoder wheel to detect position, etc.., and they can be used in many other circuits where optical links and transitions are needed. As a result, optical couplers or photocouplers are found in a high number of circuits.
Construction
All optocouplers consists of two elements a light source which is almost always a light emitting diode(LED) and a photosensor typically, photodiode, phototransistor, silicon controlled rectifiers (SCR) or triac. Both of these elements are separated by a dielectric
(monoconducting) barrier.
Working Principle
When input current is applied to the LED, it switches ON and emits infrared light; the photosensor then detects this light and allows current to flow through the output side of the circuit. Conversely, when the LED is off, no current will flow through the photocoupler. By this method, the two flowing currents are electrically isolated. It consists of LED and photo diode where the circuits are isolated electrically. In fig LED is forward biased, photodiode is reverse biased and output exists across R2.
The fig (a) describes the basic operation of an optocoupler. When current is not being applied via pin 1, the LED is off, and the circuit connected to pin 4 and 5 is experiencing no current flow. When power is applied to the input circuit, the LED switched on, the sensor detects the light, closes the switch and initiates current flow in the output circuit, as shown in fig (b).
Application:
1.Input and output swtiching, especially in electronically noisy environments
2.Switch-mode power supplies
3.Signal isolation
4.Power control
5.PC/ modem communications
6.Controlling transistors and triacs
SUBROUTINES
Subroutines definition
Subroutines working
Hello everyone!
Subroutines definition
Subroutines working
Hello everyone!
I am here again on another topic ..
WHAT ARE SUBROUTINES?
What do you think is subroutine?
Well I will walk you through this!
Lets begin!
Subroutines :
A Subroutine is a group of instruction, that performs a particular subtask which is executed number of times. It is written separately.
The processor executes this subroutine by transferring program control to the subroutine program. After completion of subroutine program execution, the program control is returned back to the main program. The use of subroutine is very important technique in designing software for processor systems because it eliminates the need to write the subtasks repeatedly; thus it uses memory more efficiently. When a program branches to a subroutine we say that it is calling the subroutine. The instruction that performs the branch operation is referred to as call instruction. After completion of subroutine program execution, the program control is returned back to the main program by executing a return instruction. Since the subroutine may be called from different places in a calling program, provision must be made for returning to the appropriate location, i.e., the next instruction from where the subroutine is called from the calling program. When the call instruction is executed the PC is updated to point to the next instruction. The updated content of the PC are saved by the call instruction to enable correct return to the calling program.
The technique by which a computer makes it possible to call and return from subroutines is referred to as its subroutine linkage method. The simplest method is to save the return address in a register dedicated to this function. Such a register is called link register. Lets see how the call and return operations are performed.
Call operation :
- It stores the contents of the PC in the link register.
- It then branches the program control to the target address specified by the instruction.
- It loads the PC with the contents of link register and branches to the next instruction from where the subroutine is called.
Hello everyone!
Today we'll be learning about addressing modes
What do you think an addressing mode is ?
Okay in simple words, The different ways that a person can access data are referred to as addressing modes or also called addressing schemes.
Let us see how addressing modes are used
1. Register mode : The operand is the contents of processor register. The name of register is specified in the instruction.
2. Absolute mode or direct mode : The address of the location of the operand is given explicitly in the instruction.
The constant for address and data can be represented by immediate addressing mode in the assembly language programming.
3. Immediate mode : The operand is given explicitly in the instruction.
Example: MOV #20, A
The above instruction copies operand 20 in the register A. The sign # in front of the value of an operand is used to indicate that this value is an immediate operand.
4. Indirect mode : The effective address of the contents of a register or the main memory location whose address is given explicitly in the instruction.
Example: MOV (R0), A
The above instruction copies the contents of the memory addressed by the memory address given in the instruction in parentheses.
The register or memory location which provides the address of the operand is known as pointer.
5. Index mode : The effective address of the operand is generated by adding a constant value to the contents of a register.
Example: MOV R2, 20 (R1)
The above instruction loads the contents of register R2 into the memory location whose address is calculated by addition of the contents of register R1 and constant value 20
6. Relative Addressing mode : The effective address is determined by the index mode using program counter in place of the general purpose processor register.
This addressing mode is commonly used to specify the target address in branch instructions.
Example: JNZ BACK
This instruction causes program execution to go to the branch target location identified by the name BACK, if the branch condition is satisfied. The branch target location can be determined by specifying it an offset from the current value of the program counter. Since the branch target location may either before or after the branch instruction, the offset is specified as a signed number.
7. Auto increment mode : The effective address of the operand is the contents of a register specified in the instruction. After accessing the operand, the contents of the register are incremented to address the next location.
Example: MOV R0, (R2)+
The above instruction copies the contents of register R0 into the memory location whose address is specified by the contents of R1. After copy operation, the contents of register R2 are automatically incremented by 1.
8. Auto decrement mode : The contents of a register specified in the instruction are decremented and then they are used as an effective address to access a memory location.
Example: MOV -(R0), R1
This instruction initially decrements the contents of register R0 and then the decremented contents of register R0 are used to address the memory location. Finally, the contents from addressed memory location are copied into the register R1.
Thank you everyone!
Hope you all understand
And I hope that this is beneficial for you all!
Today we'll be learning about addressing modes
What do you think an addressing mode is ?
Okay in simple words, The different ways that a person can access data are referred to as addressing modes or also called addressing schemes.
Let us see how addressing modes are used
1. Register mode : The operand is the contents of processor register. The name of register is specified in the instruction.
Example: MOV R2, R1
This instruction copies the contents of register R2 to R1.
2. Absolute mode or direct mode : The address of the location of the operand is given explicitly in the instruction.
The constant for address and data can be represented by immediate addressing mode in the assembly language programming.
3. Immediate mode : The operand is given explicitly in the instruction.
Example: MOV #20, A
The above instruction copies operand 20 in the register A. The sign # in front of the value of an operand is used to indicate that this value is an immediate operand.
4. Indirect mode : The effective address of the contents of a register or the main memory location whose address is given explicitly in the instruction.
Example: MOV (R0), A
The above instruction copies the contents of the memory addressed by the memory address given in the instruction in parentheses.
The register or memory location which provides the address of the operand is known as pointer.
5. Index mode : The effective address of the operand is generated by adding a constant value to the contents of a register.
Example: MOV R2, 20 (R1)
The above instruction loads the contents of register R2 into the memory location whose address is calculated by addition of the contents of register R1 and constant value 20
6. Relative Addressing mode : The effective address is determined by the index mode using program counter in place of the general purpose processor register.
This addressing mode is commonly used to specify the target address in branch instructions.
Example: JNZ BACK
This instruction causes program execution to go to the branch target location identified by the name BACK, if the branch condition is satisfied. The branch target location can be determined by specifying it an offset from the current value of the program counter. Since the branch target location may either before or after the branch instruction, the offset is specified as a signed number.
7. Auto increment mode : The effective address of the operand is the contents of a register specified in the instruction. After accessing the operand, the contents of the register are incremented to address the next location.
Example: MOV R0, (R2)+
The above instruction copies the contents of register R0 into the memory location whose address is specified by the contents of R1. After copy operation, the contents of register R2 are automatically incremented by 1.
8. Auto decrement mode : The contents of a register specified in the instruction are decremented and then they are used as an effective address to access a memory location.
Example: MOV -(R0), R1
This instruction initially decrements the contents of register R0 and then the decremented contents of register R0 are used to address the memory location. Finally, the contents from addressed memory location are copied into the register R1.
Thank you everyone!
Hope you all understand
And I hope that this is beneficial for you all!
- The computer center manager running a large server system may say a computer is faster when it completes more jobs in an hour. The computer user is always interested in reducing the time between the start and the completion of the program or event, i.e. reducing the execution time.
- The execution time is also referred to as response time.
- Reduction in response time increases the throughput(the total amount of work done in a given time).
- The performance of the computer is directly related to throughput and hence it is reciprocal of execution time.
- The ideal performance of the computer system is achieved when we have a perfect match between the machine capability and the program behavior.
- The machine capability can be enhanced with better hardware technology innovative architectural features, and efficient resources management.
- However, program behavior is difficult to predict since it heavily depends on application and run time conditions. The program behavior also depends on the algorithm design, data structures used, language efficiently, programmer skill and compiler technology.
Hello Everyone
Today's topic is data structures
Today we shall learn about:
- Data structure
- Types of data structures
Before starting I would like to tell you which book I prefer
DATA STRUCTURES AND APPLICATIONS(a simple and systematic approach)
~A.M. PADMA REDDY, BE, M.TECH, MISTE
Sai Vidya Institute of technology
This is an awesome book, you can understand all the concepts very clearly!
Now I would like to start!
Define data structures?
Definition: It means that the way the values are structured or organized or stored in memory.
Various types of data structures are:
- Primitive data structure
- Non-primitive data structure
The data structures that can be manipulated directly by machine instructions are called primitive data structures. Thus, the primitive data structures are fundamental data types that are supported by a programming language. The primitive data structure are also called simple data structures.
For example, in C, the different primitive data structures are defined using the data types such as int, float, char, double and pointers.
NON PRIMITIVE DATA STRUCTURES
The data structure where its values or elements are stored in a sequence or linear order is called linear data structure. The elements can be accessed sequentially one after the other in a linear order and hence the name. The linear relationship between the elements is maintained.
For example, arrays, queues, stacks, linked lists, etc..., are all linear data structures.
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SUBROUTINES Subroutines definition Subroutines working Hello everyone! I am here again on another topic .. WHAT ARE SUBROUTINES?...
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