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Tuesday, July 22, 2014

Mac OS

The Mac OS is designed to run on Machintosh computers .
It is a very powerful and easy-to-use operating system .It is the world most advanced operating system and the newest version of OS X is free with strongest security.
The latest version of the Machintosh operating system is OS X. This operating system provides a number of unique features:

Aqua is an intuitive user interface.
Dock provides a flexible tool for organizing files.
Sherlock locates information on the Web as well as on the user's computer system.

Figure :- OS X

OS X:-
OS X is the line of graphical operating systems developed, marketed, and sold by Apple Inc.
which succeeded the original Mac OS, which had been Apple's primary operating system since 1984.

Unlike the earlier Macintosh operating system, OS X is a Unix-based operating system built on
technology developed at NeXT from the second half of the 1980s until early 1997,
when Apple purchased the company.

Latest version of OS X is OS X Yosemite (version 10.10) is the upcoming eleventh major release of OS X, Apple Inc.'s desktop and server operating system for Macintosh computers. OS X Yosemite was announced and released to developers and beta testers on June 2, 2014, at WWDC 2014. Yosemite will be released to consumers in late 2014.Following the new naming scheme introduced with OS X Mavericks, Yosemite is named after the national park in California.
System requirements:-No changes in system requirements have been made for Yosemite, meaning that all Macintosh products capable of running OS X Mavericks will be supported by Yosemite; as with Mavericks, 2 GB of RAM, 8 GB of available storage, and OS X 10.6.8 (Snow Leopard) or later are required.

Device Drivers

What are Device drivers? How are device drivers updated?
Answer:-

Device drivers are specialized programs that allow device such as mouse, printer, scanner or keyboard to communicate with the rest of the computer system.

Every device, such as a mouse or printer , that is connected to a computer system, has a special program associated with it. This program , called a device driver or simply a driver, works with the operating system to allow communication between the device and the rest of the computer system.
Each time the computer system is started, the operating system loads all the device drivers into memory.

Whenever a new device is added to a computer system, a new device driver must be installed before the device can be used .
Windows supplies hundreds of different device drivers with its system software. If a particular device driver is not included , the product's manufacturer will supply one.
Many time these drivers are available directly form manufacturer's website.

You probably never think abut the drivers in your computer.
However when your computer behaves unpredictably , you find updating your drivers solves your problems.
Windows makes it easy to update the drivers on your computer using Windows Update.

Sunday, July 20, 2014

Process States and Transitions

List containing complete set of process states:
1. The process is executing in user mode.
2. The process is executing in kernel mode.
3. The process is not executing but is ready to run as soon as the kernel schedules it.
4. The process is sleeping and resides in main memory .
5. The process is ready to run , but swapper (process 0) must swap the process into main memory before the kernel can schedule it to execute.
6. The process is sleeping, and the swapper has swapped the process to secondary storage to make room for other processes in main memory.
7. The process is returning from the kernel to user mode ,but the kernel preemprts it and does a context switch to schedule another process.The distinction between this state and state 3 (ready to run) will be brought out shortly.
8. The process is newly created and is in a transition state ; the process exists, but it is not ready to run , nor is it sleeping . This state is the start for all processes except process 0.
9. The process executed the exit system call and is in the zombie state. The process no longer exists , but it leaves a record containing an exit code and some timing statistics for its parent process to collect .The zombie state is the final state of a process.

Buffer

Definition :-
The kernel could read and write directly to and from the disk for all file system accesses,but system response time and throughput would be poor because of the slow disk transfer rate . The kernel therefore attempts to minimize frequency of disk access by keeping a pool of internal data buffers,called the buffer cache which contains the data in recently used disk blocks.

A buffer contains two parts:
a memory array that contains data from the disk and
a buffer header that identifies the buffer.

The status of buffer is a combination of the following conditions:
1. The buffer is currently locked.
2. The buffer contains valid data
3. The kernel must write the buffer contents to disk before reassigning the buffer this condition is known as "delayed-write"
4. The kernel is currently reading or writing the contents of the buffer to disk.
5. A process is currently waiting for the buffer to become free

Structure of the buffer pool:
The kernel caches data in the buffer pool according to a least recently used algorithm .
The kernel maintains a free list of buffers that preserves the last recently used order.
The free list is a doubly linked circular list of buffers with a dummy buffer header that marks its beginning and end .
Kernel organizes the buffer into separate queues, hashed as a function of the device and block number.

Five typical scenarios the kernel may follow in getblk to allocate a buffer for a disk block
1. The kernel finds the block on its hash queue, and its buffer is free.
2. The kernel cannot find the block on the hash queue,so it allocates a buffer from the free list .
3. The kernel cannot find the block on the hash queue and in attempting to allocate a buffer from the free list ,finds a buffer on the free list that has been marked "delayed write." The kernel must write the "delayed write" buffer to disk and allocate another buffer.
4. The kernel cannot find the block on the hash queue , and the free list of buffers is empty.
5. The kernel finds the block on the hash queue , but its buffer is currently busy.

Monday, July 14, 2014

Solve and Test Arithmetic questions

Q1. The base of a triangular field is three times its altitude.If the cost of cultivating the field at Rs.24 per hectare be Rs.324, find its base and height.

Ans. Height = 300m , base= 900m

Q2 The average monthly expenditure of a family was Rs.4,050 during first 3 months, Rs. 4,260 during next 4 month and Rs.4,346 during last 5 month of the year. If the total saving during the year be Rs.8,720, find the average monthly income.

Ans. Rs. 4,970

Q3 The student in three classes are in the ratios 2:3:5. If 20 students are increased in each class ,the ratios changes to4:5:7. What is the total number of student before the increase?

Ans. 100

Q4 A papaya tree was planted 2 year ago. It increase at the rate of 20% every year . If at present , the height of the tree is 540 cm, What was it when the tree was planted?

Ans. 375 cm

Q5 The sum of the ages of a father and son is 45 year. Five year ago , the product of their ages was 4 times the father's age at that time.Find the present ages of the father and son.

Ans. Father's age i.s 36 year and son 's age is 9 years

Q6. A man sold an article for Rs.161, gaining 1/6th of his outlay. Find the cost price of the article.

Ans. Rs. 138

Q7. Divide Rs.560 among A,Band C so that A may get half as much as C and B may get half as much as C.

Ans. A's shave =Rs. 140, B's shave =Rs. 140, C 's shave= Rs.280

Q8. If in a long division sum ,the dividend is 380606 and the successive remainders from the first to the last are 434,125 and 413,find the divisor.

Ans. 843

Q9. In a hostel there were some students.Average expenditure on their meal was Rs.60.10 more students joined and the expenses increased by Rs.350 ,but average reduced by Rs. 5 .How many students were in the hostel originally?

Ans. 40

Q10. A grocer purchased 80 kg of rice at RS .13.50 per kg and mixed it with 120 kg available at Rs. 16 per kg.At what rate per kg should he sell the mixture to have a gain of 20 per cent?

Ans. Rs 18 per kg

Saturday, July 12, 2014

Solve More GK Qs

General Knowledge Questions :-

1) What should be the minimum interval between two successive blood donations?
A) 6 weeks
B) 3 months
C) 6 months
D) 8 months

Ans::- B) 3 months

2) Food is mainly digested in-
A) Liver
B) Large intestine
C) Small intestine
D) Mouth

Ans::- C) Small intestine

3) The large cell in the human body is -
A) Nerve Cell
B) Muscle Cell
C) Liver Cell
D) Kidney Cell

Ans::- A) Nerve Cell

4) Which of the following is a flightless bird?
A) Emu
B) Hen
C) Swan
D) None of these

Ans::- A) Emu

5) Meningitis is a disease which affects the -
A) Kidneys
B) Liver
C) Heart
D) Brain

Ans::- D) Brain

6) Which of the following is a vector quantity?
A) Force
B) Momentum
C) Energy
D) Temperature

Ans ::- A) Force

7) The three famous Buddhist sites Ratanagiri ,Lalitgiri and Udaigiri are located in which of the following States?
A) Bihar
B) Maharashtra
C) U.P.
D) Orissa

Ans:: - Orissa

8) Who among the following earned the title of a 'Liberator'?
A) Chandragupta Vikramaditya
B) Ashoka
C) Chandragupta Maurya
D) Alexander

Ans::- C) Chandragupta Maurya

9) The strategy of 'Divide and Rule' was adopted by whom?
A) Lord Curzon
B) lord Welleslely
C) Lord Minto
D) Lord Canning

Ans:: - C) Lord Minto

10) Delhi became the Capital of India in -
A) 1910
B) 1911
C) 1916
D) 1923

Ans ::- B) 1911

11) The first President of independent India was -
A) Dr. Rajendra Prasad
B) M.K.Gandhi
C) Dr. S.Radhakrishnan
D) J.L.Nehru

Ans::- A) Dr. Rajendra Prasad

12) Who was the first European to translate the Bhagwad Gita into English?

A) William Jones
B) Charles Wilkins
C) James Prinsep
D) Sir Alexander Cunningham

Ans:: -B) Charles Wilkins

13. The population of which of the following is maximum on the earthA) Reptiles
B) Fishes
C) Birds
D) Beetles

Ans. B) Fishes

14. Which of the following is the largest living mammal?
A) Giraffe
B) White elephant
C) Rhinoceros
D) Blue Whale
Ans. D) Blue Whale

15. Which first is given by a herb?A) Mango
B) Banana
C) Apple
D) Jack- fruit
Ans. D) Jack- fruit

16. Which of the following is hereditary?
A) Dysentery
B) Tuberculosis
C) Haemophilia
D) Cancer

Ans. C) Haemophilia

17. Which of the following is knows as the jain Temple City?
A) Gimar
B) Rajagriha
C) Varanasi
D) Ilahabad

Ans. A) Gimar

18. Who was the first King to conquer Malwa,Gujarat and Maharashtra?A) Skandagupta
B) Samudragupta
C) Chandragupta Maurya
D) Harshavardhena

Ans. C) Chandragupta Maurya

19. The slogan 'Inquilab Zindabhad' was raised by whom?A) Lokmanya Tilak
B) Veer Savarkar
C) Chandrashekar Azad
D) Bhagat Singh

Ans. D) Bhagat Singh

20. The Muslim League started demanding a separate nation for the Muslims from which year?
A) 1919
B) 1925
C) 1929
D) 1940

Ans. D) 1940

21. When did the British Parliament pass the Indian Independence Bill ?
A) 20th February, 1947
B) 24th March, 1947
C) 1st July, 1947
D) 14th August,1947

Ans. C) 1st July,1947

22. Who among the following has the final power to maintain order within the House of People?A) Marshal of the People
B) Prime Minister
C) Speaker
D) Chief of Security Staff

Ans. C) Speaker

23. Which is laughing gas?
a) Carbon dioxide
b) Sulphur dioxide
c) Carbon monoxide
d) Nitrous oxide
Ans. d) Nitrous oxide

24. Detergents used for cleaning clothes and utensils contains-a) Nitrates
b) Bicarbonates
c) Sulphonates
d) Bismutnates

Ans. c) Sulphonates

25. Floppy disc in a computer system is-a) Compiler
b) Core memory
c) Software
d) Device for storage and retrieving data
Ans. d) Device for storage and retrieving data

26. The tooth with there roots is-a) Molar
b) Pre- Molar
c) Incisor
d) CanineAns. a) Molar

27. Bamboo is a-
a) Grass
b) Herb
c) Shrub
d) Tree

Ans. a) Grass

28. Which of the following cannot be controlled by vaccination?
a) Small pox
b) Diabetes
c) Polio
d) Whooping cough
Ans. b) Diabetes

29. Which of the following terms is used for several individuals of a species living together in a locality?a) Biosphere
b) Ecosystem
c) Bio- community
d) PopulationAns. c) Bio- community

30. Raman effect is associated with characteristics of-a) Heat
b) Light
c) Electricity
d) Magnetism
Ans. b) Light

31. Which of the following is known as the queen of spices?
a) Coriander
b) Cardamom
c) Fenugreek
d) ChilliesAns. b) Cardamom

32. The Peacock throne was made for -a) Jahangir
b) Akbar
c) Shahjehan
d) Aurangzeb

Ans. c) Shahjehan

33. Which of the following was built by Akbar?
a) Agra fort
b) Fort of Daulatabad
c) Red fort
d) Fort of AhmednagarAns. a) Agra fort

34. Ramayan refers to-a) Satyuga
b) Tretayuga
c) Dwaparyuga
d) Kalyuga
Ans. b) Tretayuga

35. Who is regarded as the greatest law giver of ancient India?a) Kautilya
b) Manu
c) Panini
d) Patanjali
Ans. b) Manu

36. When did the Indian National Congress ask for the 'Dominion Status'?a) 1908
b) 1929
c) 1942
d) 1947
Ans. a) 1908

37. The first woman's university in India was founded by-a) Gandhiji
b) J.K.Kumarappa
c) Dhondo Keshave Karve
d) Rani Ahilya Devi

Ans. c) Dhondo Keshave Karve

Wednesday, July 9, 2014

Full form of

Full Forms Of::-

Write full form of :

AGP ::- Accelerated Graphics Port

AI ::- Artifical Intelligence

ALU ::- Arithmetic Logic Unit

AOL ::- American Online

ARPANET ::- Advanced Research Project Agency Network

ASCII   ::-American Standard Code for Information Interchange

ATM ::- Automated Teller Machine

B2B ::- Business To Business

B2C ::- Business To Consumer

C2C ::- Consumer To Consumer

CCTV (camera)::- Closed-Circuit Television (camera)

CD ::- Compact Disc

CERN ::- Center for European Nuclear Research

CISC ::- Complex Instruction Set Computer

CMOS   ::- Complementary Metal Oxide Semiconductor

CPU   ::- Central Processing Unit

CRT ::- Cathode Ray Tube

DBMS ::- Database Management System

DNS ::- Domain Name System

DSL ::- Digital Subscriber Line

DVD ::- Digital Versatile (or Video ) Disc

EBCDIC   ::- Extended Binary Coded Decimal Interchange Code

E-Mail ::- Electronic mail

FTP ::- File Transfer Protocol

HDTV ::- High Definition Tele Vision

HPSB ::- High Performance Serial Bus

HTML ::- Hyper Text Markup Language

HTTP ::- Hyper Text Transfer Protocol

IP ::-   Internet Protocol

IRC ::- Internet Relay Chat

ISA ::- Industry Standard Architecture

ISP ::- Internet Service Provider

IT ::- Information Technology

LAN ::- Local Area Network

LCD ::- Liquid Crystal Display

MAN ::- Metropolitan Area Network

MICR ::- Magnetic Ink Character Recognition

NIC ::- Network Interface Card

NOS   ::- Network operating System

OCR ::- Optical Character Recognition

OLE ::- Object Linking and Embedding

OMR ::- Optical Mark Recognition

PC ::- Personal Computer

PCI ::- Peripheral Component Interconnect

PCMCIA ::- Personal Computer Memory Card International Association

PDA ::- Personal Digital Assistant

RAID ::- Redundant Arrays of Inexpensive Disks

RAM ::- Random Access Memory

RISC ::- Reduced Instruction Set Computer

ROM ::- Read Only Memory

SQL ::- Structured Query Language

SVGA ::- Super Video Graphics Array

SXGA ::- Super Extended Graphics Array

TCP ::- Transmission Control Protocol

TFT ::- Thin Film Transistor

TV ::-   Tele Vision

UPC ::- Universal Product Code

URL ::- Uniform Resource Locators

USB ::- Universal Serial Bus

UXGA ::- Ultra Extended Graphics Array

VR ::- Virtual Reality

VRML ::- Virtual Reality Modeling Language

WAN ::- Wide Area Network

WWW ::- World Wide Web

XGA   ::- Extended Graphics Array