The Multics virtual memory: concepts and design

The Multics virtual memory: concepts and design, A. Bensoussan, C. T. Clingen and R. C. Daley, Communications of the ACM, Vol. 15, NO. 5, May 1972, pp. 308 – 318.

As we might know, the use of on-line operating systems has been growing as well as the need to share information among system users. However, they share by the use of segmentation. This motivated the authors, such that, in order to take advantage of the direct addressability of large amounts of information which made possible by large virtual memories, the authors are motivated to develop a Multics (Multiplexed Information and Computing Service) to provide a generalized basis for the direct accessing and sharing of online information. There are two goals; the first goal is it must be possible for all on-line information stored in the system to be addressed directly by a processor. Another goal is that it must be possible to control access.

Regarding to the authors contributions, the authors have introduced an idealized memory by using the segmentation and paging features of the 645 assisted by the software features. Also, to take some advantages of existing mechanism , the Multics processes and the Multics supervisor were introduced The symbolic addressing conventions technique also provide an ease of use for users, such that a user can reference a segment’s pathname and supplying the rest of the pathname according to system conventions. Moreover, by making a segment known to a process and improve the segment fault handler have given the Multics a lot of performance.

The paper’s single most noticeable deficiency is that there are too many assumptions, so it makes the readers pretty confused of how to use the features of the Multics. The conclusion of the paper should summarize what the authors have contributed and how to improve it in the future work, instead of showing of user and supervisor view points. It would be good if the authors emphasize of how the selection algorithm work. For the question according to the paper, I would like to know how much it improves from the old fashion of the concept.
Lastly, I would rate the significance of the paper 3(modest) due to the fact that this paper is published 30 more years ago. It lacks of experimental and compare/contrast with the use of segmentation.

How to make your own tissue box

Getting bored with the simple tissue boxes, here is how to make one of your own. The trick is all about drawing a tissue box outline, and use your toothbrush as your painting tool. I recommend you to work with water color. Mix the color as you like, cover the area with your toothbrush spreying techniques. Thats it! now you have your own cool tissue box. cake isn’t it? πŸ™‚

How to use markers

Have you ever wonder how they come up with a colorful in most of cartoon books? There is a technique of how to draw them. The picture above is one of my portfolio shows you that I can draw exactly like the cartoon cover by using markers. The trick is that you need to work with gray shading markers. It looks like a poster color but its much easier to work on small details and user friendly.

Finally Full Scale :)

Almost two years of being an AT&T loyal customer, I have been suffered with low or no signal from my area. Its very frustrated so, I went to apply a new service today and yeah before I open a new account, I double check for a wireless signal strength for my area. Totally recemmend for anyone who is about to get a phone service to check the wireless signal first before sign up for an account.

7 Habits of Highly Effective People

I have been reading “The Seven Habits of Highly Effective People”, one of the books that my brother recommend me to read years ago, since I was 19-20, and I just finished reading the book today. Whew πŸ™‚
I found the book quite interest and very useful for anyone who wants alternate way to improve or change his/herself. The book describes solid principle approaches to archive a personal effectiveness, and emphasizes of how important of the seven habits. To make the book shorten, I ran across many sites which gives a good summarize of the book as below.

http://www.leaderu.com/cl-institute/habits/habtoc.html

Oh, while I google the websites, I found a list of relevant topic about self-improvement which is written by John H. Patterson, interestingly, the list below he wrote is about 100 years ago, and still work effectively today.
Physically
1. Simple food, quality, quantity.
2. Regularity in eating and sleep.
3. Masticate; leave table hungry.
4. We are a part of all we have eaten.
5. Exercise, five minutes, three times daily.
6. Air β€” most important.
7. Sunlight, artificial light.
8. Water inside and outside.
9. Loose clothing.
10. Early to sleep; get plenty.
Mentally
1. Think sanely.
2. Learn from mental superiors.
3. Learn to listen attentively.
4. Read best newspapers and books.
5. Improve the memory.
6. Concentrate.
7. Don’t worry unnecessarily.
8. Be systematic.
9. Weigh both sides.
10. Avoid inferior minds.
Morally
1. Right is right, wrong is wrong.
2. Be truthful.
3. Ignore precedent if wrong.
4. Seek elevating recreation.
5. Don’t deceive yourself.
6. Learn to say “no.”
7. Live up to your principles.
8. Avoid temptation.
9. Form good habits.
10. Have a constitution.
Financially
1. Increase my earnings.
2. Decrease unnecessary expense.
3. Save money, U.S. Postal Bank.
4. Money makes money.
5. Invest β€” don’t gamble.
6. Make family budget.
7. Hard work.
8. Study the business.
9. Pay cash for everything.
10. Increase credit balance.
Socially
1. Avoid bad associates.
2. Select helpful friends.
3. Think alone.
4. Learn to be happy alone.
5. Family best company.
6. Work out, alone, my problems.
7. Avoid so-called society.
8. Entertain economically.
9. Stand well with neighbors.
10. Do some welfare work.

Starcraft 2 here it comes

Been waiting for this game almost ten years since 1998, a great game that I recommend for everyone to play. A true intense real time stretegy, An epic master piece game in history. The clip below is a game demo for terran units.

Why Thread?

Here is a quick brief about a concept of thread. Thread is a light weight process, it takes less time to create, context switch or destroy thread than a process. We want simultaneous activities for a better interraction with a user or take advantages of multi-processors to archieve a maximum system resourse utilization.

For instance, in word processor, one thread responses for I/O, while another is doing a grammar check. Now, lets take a look at a simple JAVA program to see how the thread create, run, and how threads assignment work in JAVA.


public class thread extends Thread{
public void run() {
for(int i = 0; i < 10; i++) {
System.out.println("Child thread " + i);
}
}

public static void main(String[] args) {
thread t = new thread();
t.start();

for(int i = 0; i < 10; i++) {
System.out.println("Parent thread " + i);
}
}// end main
}// end class thread

In the code above, we created two threads. When the new thread create, it will go to the run() method and do the job, so we can see from the output from the program that there will be two threads execute concurrently.

program output:

Parent thread 0
Parent thread 1
Child thread 0
Parent thread 2
Child thread 1
Parent thread 3
Child thread 2
Parent thread 4
Child thread 3
Parent thread 5
Child thread 4
Parent thread 6
Child thread 5
Parent thread 7
Child thread 6
Parent thread 8
Child thread 7
Parent thread 9
Child thread 8
Child thread 9