Segementing how a microprocessor manages more than 64K of memory

April 25, 2013

Segmenting is a memory management technique which microprocessors use to address more than 64kilobytes memory.In this example I will demonstrate how
Intel 8086 accomplishes addressing more than 65K memory.

A memory word is addressed by addressing by  adding a segment pointer and a word address as shown
in the picture.

The possibility of addressing one megabyte doesn’t necessary mean that the processor has a physical memory of 1MB.
You can make a program as if the processor had 1MB of memory and the
processor can fetch the segment that is being addressed from the computers hard drive.

moreThan64KAdressing

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Writen by: Rikard Grossman-Nielsen
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The general parts of a microprocessor and a chart which describes the history and classification of processors

September 29, 2012
Basic Parts of a Microprocessor.

Basic Parts of a Microprocessor.

If we start in the upper half of the schematics you will find components all microprocessors must have: a control unit, an arithmetic unit (AE in th picture), an different kinds of registers.

The control unit is built around a microcode program in most microprocessors. The microcode is stored in a rom. This has two advantages first a rom increase the ammount of logic which you can implement per square inch, second it is easy to upgrade the microcode within the rom to implement new features and bug fixes.

If we look to the right we will find the data and adress registers of the processor. The dataregisters are 8bit wide and the adressregisters are 16bits wide. Among the adress registers you can find registers such as PC(Program Counter), SP(Stack Pointer) and others. The program counter points to the memory adress of the next instruction for the microprocessor to perform and decode. The stack pointer points to the stack where the data and instructions are stored.

Furthermore you can find i/o registers which are used for the processorer to perform i/o operations directly without acessing the random acess memory. One examole of such an operation is a DMA(Direct Memory Acess operation).

Outside the dotted box you cand find the chips which are needed to make a complete computers systems.
These are:
-ROM and RAM chips
-UART chips for serial communication
-PIO chip for parallel communication
-DAC(Digital Analog Converter) chip, which converts signals between analog and digital form.

There also one chip micro computer chips where all of the above chips are integrated in order to fit a complete computer onto one single chip.

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How microprocessors handle interrupts:interrupt management

July 31, 2012

Intetrrupts are made asynchronously to the main code which is executed whereas polling is performed syncronously to the application being executed. The main advantage of interrupts are that they give a short reponse time if we assume that several interrupts are not made at the same time. In realtime systems which must respond to events very fast interrupts must be used to achieve a quick enoguh response.

The three disadvantages of interrupts are:

1. They require extra hardware, especially if interrupt management is to be done outside the processor.
2. Each time an interrupt is made, a time is needed to handle the interrupt. This ammount of time is called overhead.
3. The interrupt routine is exected aschynorously to the the main thread which means that it’s diffciult to know how much memeory that needs to be allocted for interrupt management.

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Writen by: Rikard Grossman-Nielsen,
ITService-GNR (ITTjänst-GNR),
www.ittjanstgnr.se
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Endomondo an andriod app to boost your fitness!

June 20, 2012

Endmondo is a great app to keep fit. The best thing with endomondo is that it easy to use. It has a screen which gives a clear overview of the current workout. Another screen gives a clear overview of the last performed work outs.The application has an Audio Coach which gives you a pep talk by giving you information on your lap time and total time on regular intervals such as every kilometer. Furthermore you can connect bluetooth accessories such as a polar heart rate monitor and let endomondo record your beat during workouts.

The PRO version also gives more detailed information on your workout such as altitude and speed graphs. Furthermore you can connect with your Facebook friends and see their workouts in the friends tab of the application. Another good thing about endomondo is that can calculate calorie usage for quite a few exercise activities compared to many other tracker applications.

Endo Mondo Friend Screen

Endo Mondo Map View

Endo Mondo workout screen

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Writen by: Rikard Grossman-Nielsen,
ITService-GNR (ITTjänst-GNR),
www.ittjanstgnr.se
Technorati token: F6U8ZD2JJGDG

Today I attended an interesting seminar on how to teach children with autism.

May 17, 2012

The seminar featured a film. It was on a method the son-rise method can provide amazing results ..
The documentary depicted the fantastic progress of a child which came to a center where they used the training method called son-rise.
I must say that the results show in the film were quite amazing.

If I would attempt an analysis of the method from a pedagogical standpoint I would say that pedagogy is inspired by the sociocultural perspective where view things from a group perspective and how the surroundings of the individual effects the learning situation. It also feels like it draws inspiration from the pedagogy that studies the internal cognitive development of the individual such as Piaget. It also feels as the sonrise method places a lot of emphasis on seeing the possibilities of the individual rather than seeing the individual as just another child which has a disorder called autism. The staff in the movie sees the individual by learning to know each child that comes to the center and tailoring a training programme for that particular individual rather than using a standard programme which has the same structure for every child.

If you which to know more about this method you can check out:
The autism treatment center.

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Writen by: Rikard Grossman-Nielsen
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How microprocessor perform I/O mangament:polling, direct memory acess and interrupts

May 9, 2012

This post will be abou the first method called polling. The next two posts will cover the other methods.
The first method is called polling. Polling is also called programmed I/O, and it’s also the simplest one to implement from a hardware perspective. I/O units are connected to the system data and an address buss in a  regular fashion trough necessary circuitry. Depending on the type of microprocessor they can also be connected to certain lines on the control buss.

The goal with a communication schedule is to have a well ordered procedure to decide what I/O unit is to be served by the processor next. Polling is a synchronous method since it doesn’t interrupt the program which is currently executed by the microprocessor. When polling is used the microprocessor will on regular intervals ask each unit connected to the data buss if it needs to be served.  The sensing if a unit needs to be served is in practice done by sensing a flag bit in the status registry of the unit.

The advantages of polling are:
1. It requires very little hardware and no dedicated lines.
2. it’s synchronous with the execution of the prgoram. This is a big advantage since the programmer know s exctly when an external unit is polled and who long time it takes to serve that unit.

The disadvantages of polling are:
1. It requires special hardware if interrupt management is to be done outside the microprocessor.
2. Each time an interrupt is made, there’s an overhead time to manage the interrupt

Description of polling techonology

Description of polling techonology

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How to program a simple andriod application that converts kilo calories to kilo joules

April 25, 2012

I decided to learn some android programming and therefore I decided to code a small android application which converts a given amount of energy from kilocalories to kilojoules and from kilocalories to kilojoules. I chose to code such an app since I’m trying to get fit for the summer and record what I eat into shapeup club. I usually think about calorie intake in terms of kilojoules but the shapeub club only accepts kilocalories. So therefore I figure out how many kilojoules I’ve taken in and use this app to find out how man kilocalories I should add in the shapeup club app. The application itself is quite simple it has to buttons which starts two functions that perform conversions. The result of a function calls is recorded on one of the programs to result fields. The result field is a simple textview control which is updated with the settext() method.

My andriod app

My andriod app

The source code is as follows:
package com.example.test5;

import android.app.Activity;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.TextView;
import android.widget.Toast;

public class Test5Activity extends Activity {
/** Called when the activity is first created. */
Button btnCalcKj=null;
Button btnCalcKcal=null;
EditText edTxtNumKcal=null;
EditText edTxtNumKj=null;
TextView tvCompKj=null;
TextView tvCompKcal=null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btnCalcKj=(Button)findViewById(R.id.btnCalcKj);
btnCalcKcal=(Button)findViewById(R.id.btnCalcKcal);
edTxtNumKcal=(EditText)findViewById(R.id.edTxtNumKcal);
edTxtNumKj=(EditText)findViewById(R.id.edTxtNumKj);
tvCompKcal=(TextView)findViewById(R.id.tvCompKcal);
tvCompKj=(TextView)findViewById(R.id.tvCompKj);
tvCompKcal.setText(“”);
tvCompKj.setText(“”);
btnCalcKcal.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try{
// Perform action on click
double numKcal=calcNumKcal(Double.parseDouble(“”+edTxtNumKj.getText()) );
tvCompKcal.setText(“”+numKcal);
tvCompKj.setText(“”);
edTxtNumKcal.setText(“”);
edTxtNumKj.setText(“”);
}
catch(Exception e){
}
}
});
btnCalcKj.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Perform action on click
try{
double numKj=calcNumKj(Double.parseDouble(“”+edTxtNumKcal.getText()) );
tvCompKj.setText(“”+numKj);
tvCompKcal.setText(“”);
edTxtNumKj.setText(“”);
edTxtNumKcal.setText(“”);}
catch(Exception e){
}
}
});
}
private  double calcNumKj(double Kcal){
return Kcal*4.12;
}

private double calcNumKcal(double Kj){
return Kj/4.12;
}
}

You can also download the source code by clicking the link below. Get this app running by creating a new android 2.3.3 project in Eclipse named “Test5”. Thereafter you paste all of the code above into the file called “Test5Activity”.

Source code

Sony W518a an interesting feature phone with a shake function

April 16, 2012

I found an interesting feature phone called Sony Ericsson W518a.
You can control certain features by shaking the phone. One is example is changing tracks. Check it out at here.

Durrocomm Andriod – a truly rugged andriod handset!

April 10, 2012

While browsing the web I found a truly rugged handset called Durrocom Andriod. It is military certified which means that it withstands shocks and vibrations better than those phones which are only waterproof such as the Motorola Defy or Sony Ericsson Xperia Active. Except the military certification it also has an IP67 certification which means it can withstand being submerged in 1 metre of water up to 30minutes.  It measures 125 x 65 x 21 mm. It weighs in at 180g. It has a talk time of 5.5hrs and a standby time of 400hrs. It has 3G, WCDMA, Quadband GSM. It runs andriod 2.3. It has a capacitive screen and 5MP camera. It also features a torch, gps and a compass. Furthermore the phone is able to handle dual sim cards so you can use it both for work and play.

You can also check out Durrocomms homepage.
You can alo check out this Youtube video

Durrocomm Andriod - a rugged andriod phone

Durrocomm Andriod – a rugged andriod phone

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Test the graphing function of google!

April 7, 2012

Here’s something for you math majors and all other people interested in mathematics! Did you know that Google can make graphs?
Try to type this sin(x)/x,1/x^2 into Google and see what you get! You can also specify within what ranges of x and y Google should draw the graph.

Google Graph of sin(x)

Google Graph of sin(x)

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