Tablet

Today's tablet computers sport touch screens ranging in size from 7- up to 13-inches. These dimensions are by no means static, and boundaries can be blurred as smartphones get larger displays

Features of tablet :-
I) Hardware :-
1. High-definition, anti-glare display
2. Wireless local area and internet connectivity (usually with Wi-Fi standard and optional mobile broadband)
3. Front- and/or back- facing camera(s) for photographs and video
4. Lower weight and longer battery life than a comparably-sized laptop
5. Bluetooth for connecting peripherals and communicating with local devices
6. Early devices had IR support and could work as a TV remote controller.
7. Docking station: Keyboard and USB port(s)

Note:-
Special hardware: The tablets can be equipped with special hardware to provide functionality, such as camera, GPS and local data storage.

II) Software :-
1. Mobile web browser
2. Reader for digital books, periodicals and other content
3. Downloadable apps such as games, education and utilities
4. Portable media player function including video playback
5.  Email and social media
6. Mobile phone functions (messaging, speakerphone, address book)
7. Video-teleconferencing

III) Data storage :-
1. On-board flash memory
2. Ports for removable storage
3. Various cloud storage services for backup and syncing data across devices
4. Local storage on a LAN

IV) Additional inputs :-
Besides a touchscreen and keyboard, some tablets can also use these input methods:
1. Proximity sensor to detect if the device is close to something, in particular, to your ear, and can block unintended touches
2. Accelerometer: Detects the physical movement and orientation of the tablet. This allows the touchscreen display to shift to either portrait or landscape mode. In addition, tilting the tablet may be used as an input (for instance to steer in a driving game)
3. Ambient light and proximity sensors, which help distinguish between intentional and unintentional touches
4. Speech recognition
5. Gesture recognition
6. Character recognition to allow you to write text on the tablet, that can be stored as any other text in the intended storage, instead of using a keyboard.


To run your tablet smoothly:
1. Remove unnecessary apps and make more room.
2. Disable flashy settings that don’t really serve any important purpose.
3. Keep your screen clean (literally and virtually).
4. Format your external storage on a regular basis.

To install OS on your Tablet you need Android OS file that are compatible with your tablet and Software tools:
Memory card has to be made bootable. For this the PhoenixCard tool is needed.
First format the memory card, then select the  compatible Android ISO file. Please note that different tablet need different ISO files.

iPad

The iPad is not a replacement for a laptop. Tablets are good at many things, but their abilities are a subset of a laptop's. You can't, for example, burn a music CD to listen to in the car, or a DVD of your latest home movie. It isn't particularly easy to print from an iPad, either, although it is possible in some apps (you can print an email, a document or a web page if you have a compatible printer).

Features of iPad or Advantages of iPad: 
1)Battery life:
With an iPad, you'll be freed from the mains all day, since it will last for at least eight (if not 10 or 12) hours of constant use.
2)Portability and comfort:
It's more comfortable to sit and use an iPad, it doesn't get too warm and there are no fans, unlike most laptops whose high-pitched fans can drive you to distraction.
3)Touchscreen interface :
You can type very fast on the iPad's virtual, on-screen keyboard.The iPad's interface is, in general, hugely intuitive.
4)Instant on and connected standby:
An iPad doesn't take minutes to boot up: it's ready to go instantly, so it's quick to check email and Facebook, or the weather forecast or TV listings.

Disadvantages of iPad: 
1) Storage:
The iPad has no way of adding storage, so you're effectively stuck with the capacity you buy.
2)File formats:
 The iPad is much more restrictive and requires videos, for example, to be in MP4 (H.264) format before they'll play. It means you might have to convert files before you can play them, which could be more hassle than you're willing to accept.
For photos and music, the iPad supports the common JPG and MP3 formats, so these aren't a problem for most people.

Education and healthcare
The iPad has several uses in the classroom, and has been praised as a valuable tool for homeschooling.Soon after the iPad was released, it was reported that 81% of the top book apps were for children. The iPad has also been called a revolutionary tool to help children with autism learn how to communicate and socialize more easily.
In the healthcare field, iPads and iPhones have been used to help hospitals manage their supply chain. For example, Novation, a healthcare contracting services company, developed VHA PriceLynx (based on the mobile application platform of business intelligence software vendor MicroStrategy), a business intelligence app to help health care organizations manage its purchasing procedures more efficiently and save money for hospitals. Guillermo Ramas of Novation states, "Doctors won't walk around a hospital with a laptop. With an iPad it's perfect to walk around the hospital with as long as they have the information they need."
In 2013, Gianna Chien (aged 14) presented to more than 8,000 doctors at the Heart Rhythm Society meeting that Apple iPad 2 can, in some cases, interfere with life-saving heart devices (pace maker) because of the magnets inside. Apple's webpage has advised pacemaker users to keep iPads at least 6-inches away from the pacemaker.

iBooks
The iPad has an optional iBooks application that can be downloaded from the App Store, which displays books and other ePub-format content downloaded from the iBookstore.

Internet connectivity in iPad:
The iPad can use Wi-Fi network trilateration from Skyhook Wireless to provide location information to applications such as Google Maps. The 3G model supports A-GPS to allow its position to be calculated with GPS or relative to nearby cellphone towers; it also has a black strip on the back to aid 3G reception. The iPad has a headphone jack and a proprietary Apple dock connector, but no Ethernet or USB port. However, the Apple Camera Connection Kit accessory provides two dock connector adapters for importing photos and videos via USB and SD memory cards.

Global warming and green house effect

 The heating up of the earth surface due to trapping of infrared radiations reflected by earth's surface by CO₂ layer in the atmosphere is called green house effect.

Some major green house gases and their sources:

Gas	Sources
Carbon Dioxide (CO2)	1)Fossil fuel combination (coal,oil,natural gas) 2) Deforestation and land use changes
Methane (CH4)	1) Enteric fermentation in cattle and insects. 2) Biomass burning and garbage land fills 3) Leakage of gases from coal mines and natural gas. 4) Rice paddies 5) Swamps and tundra
Chloro fluoro carbon (CFC'S)	1) Plastic foams 2) Refrigeration and air-conditioning 3) Aerosols (spray propellants) CFC' 4) Industrial solvents
Nitrous oxide (N2O)	1) Fertilizer use 2) Fossil fuel combustion 3) Biomass burning 4) Changing land use

An increase in average temperature  of the earth's atmosphere due to green house effect which can have effects on climate and key life, support system of planet.
An increase in global temperature is also likely to increase the incidences of infections diseases like malaria, dengue, sleeping sickness and yellow fever.

Computer model predicts that during next 50 years the average temperature rise from 1.5 ⁰ C to 3.5 ⁰C.
Such a change ,which is very rapid by natural standards ,could have far reaching effects , especially at extreme levels .These could be in the form of
1) a rise in sea levels up-to 5 to 6 meters from the melting of ice cap and glaciers and the thermal expansions of sea water.
2) altered climate pattern altering ecosystems and
3) more extremes of weather .

Logarithm

Definition Logarithm :
If m= a ^x, where a>0 ,a not equal to 1 , m>0 then x is called the logarithm of m to the base a and is written as x = log _a m, where m, a, x are real numbers.

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Laws of logarithms:
1. Law of Product: log (A.B) =log A +log B
2. Law of Quotient : log(A/B) =log A - log B
3. Law of Exponent : log m ⁿ = n log m

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Properties:
1)We have m = a ^x if and only if x = log _a m.
2)Logarithms of negative numbers and zero are not defined.
3) a⁰ =1 Hence, 0 = log _a 1
i.e. logarithm of 1 to any base is always zero.
4) a¹ =a Hence , 1 = log _a a
i.e. logarithm of any number to the same base is 1.
5) x = log _a a^x
6) If log _a m = log _a n then m = n
7)If a>1 and m>n then log _a m > log _a n and conversely.

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Write logarithm form:
1) 5 ³ = 125
Solution:
3 = log ₅ 125   (By definition of logarithm)

2) 8 ³ =512
Solution:
3 = log ₈ 512   (By definition of logarithm)

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Express in exponential form:
1) log ₂ 128 = 7
Solution: 128 = 2 ⁷  (By definition of logarithm)

2) log ₉ 6561 =4
Solution: 6561 = 2 ⁹  (By definition of logarithm)

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Simplify : 
1) log 5 + 2 log 4
Solution:
=log 5 + log 4² (By Law of Exponent)
=log 5 + log 16
=log (5 . 16) (By law of Product)
=log 80

2) 2 log 7 - log 14
Solution:
=log 7 ² - log 14 (By Law of Exponent)
=log 49 - log 14
=log (49/14) (By law of Quotient)
=log (7/2)

3)log 3 + log 2 - 2 log 5
Solution:
=log 3 + log 2 - log 5² (By Law of Exponent)
=log 3 + log 2 - log 25
=log (3 . 2) - log 25 (By Law of Product)
=log 6 - log 25
=log (6/25) (By Law of Quotient)

4) 2 log 3 - 1/2 log 16 + log 12
Solution:
=log 3 ² - log 16 ^1/2 + log 12 (By Law of Exponent)
=log 9 - log4 + log 12
=log (9/4) + log 12 (By Law of Quotient)
=log (9/4 .12) (By Law of Product)
=log (9. 3)
=log 27

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Prove that:
1) log 540 = 2 log 2 + 3 log 3 + log 5
Solution:
L.H.S = log (540)
=log (4 X 27 X 5)
=log ( 2² X 3³ X 5)
=log 2² + log 3³ + log 5 (By Law of Product)
=2 log 2 + 3 log 3 +log 5 (By Law of Exponent)
=R.H.S.
Hence, log 540 = 2 log 2 + 3 log 3 + log 5

OR

R.H.S =2 log 2 + 3 log 3 + log5
=log 2 ² + log 3³ + log 5 (By Law of Exponent)
=log 4 + log 27 + log 5
=log (4 X 27 X 5) (By Law of Product)
=log 540
=L.H.S.
Hence, log 540 = 2 log 2 + 3 log 3 + log 5

2) log 360 = 3 log 2 + 2 log 3 + log 5
R.H.S =3 log 2 + 2 log 3 + log5
=log 2 ³ + log 3² + log 5 (By Law of Exponent)
=log 8 + log 9 + log 5
=log (8 X 9 X 5) (By Law of Product)
=log 360
=L.H.S.
Hence, log 360 = 3 log 2 + 2 log 3 + log 5

OR

L.H.S = log (360)
=log (8 X 9 X 5)
=log ( 2³ X 3² X 5)
=log 2³ + log 3² + log 5 (By Law of Product)
=3 log 2 + 2 log 3 + log 5 (By Law of Exponent)
=R.H.S.
Hence, log 360 = 3 log 2 + 2 log 3 + log 5

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Evaluate:
1) log 81/log 9
=log 9² / log 9
=2 log 9 / log 9   (By Law of Exponent)
=2

2)log ₂ 5 / log₂ 11 - log₄ 5 / log₄ 11
Solution :
We know ,Change of Base formula is log _a m = log m /log a

=log 5/log 2/log 11/log 2 - log 5/log 4/ log 11 /log 4
=log 5 . log 2 / log 11 . log 2 - log 5 .log 4 / log 11 .log 4
=log 5 / log 11 - log5 / log 11
=0

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Embedded systems

Difference between Static RAM Dynamic RAM.

Static RAM	Dynamic RAM
1. SRAM	1. DRAM
2. It retains it levels so no require refreshing	2. It requires some refreshing.
3. Power consumption is more	3. Power consumption is less.
4. Speed is fast.	4. Speed is less.
5. Package density is low.	5. Package density is high.
6. Size can't be increase.	6. Size can increase.
7. More expensive.	7. Less expensive.
8. Made up of 6 CMOS transistors(MOSFET).	8. Made up of a MOSFET and a capacitor.

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Difference between RISC and CISC processors/controllers.

RISC	CISC
1. It stands for Reduced Instruction Set Computing.	1. It stands for Complex Instruction Set Computing.
2. Lesser number of instructions.	2. Greater number of Instructions
3. Instruction pipe-lining and increased execution speed.	3. Generally no instruction pipe-lining feature.
4. Orthogonal instruction set.	4. Non-Orthogonal instruction set.
5. Operations are performed on register only, the only memory operations are load and store.	5. Operations are performed on register or memory depending on the instruction.
6. A large number of registers are available	6. Limited number of general purpose register.
7. Programmer needs to write more code to execute a task since the instruction are simpler ones.	7. Instructions are like macros in C language. A programmer can achieve the desired functionality with a single instruction.
8. Single, fixed length instructions.	8. Variable length instructions
9. Less silicon usage and pin count.	9. More silicon usage since more additional decoder logic as required.
10. With Harvard Architecture.	10. Can be Harvard or Von- Neumann Architecture.

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Difference between microprocessor and micro-controller.

Microprocessor	Micro-controller
1.A silicon chip representing a central processing unit (CPU), which is capable of performing arithmetic as well as logical operations according to a pre defined set of instructions.	1.A micro-controller is a highly integrated chip that contains a CPU, scratchpad RAM, special and general purpose register arrays, on chip ROM / FLASH memory for program storage, timer and interrupt control units and dedicated  I/O ports.
2.It is a dependent unit .It requires the combination of other chips like timers, program and data memory chips, interrupt controllers, etc. for functioning.	2.It is a self-contained unit and it doesn't require external interrupt controller , timer , UART , etc. for its functioning.
3.Most of the time general purpose in design and operation .	3.Mostly application-oriented or domain - specific.
4. Doesn't, contain a built in I/O port.The I/O port functionality needs to be implemented with the help of external programmable peripheral interface chips like 8255.	4.Most of the processor contain multiple built-in I/O ports which can be operated as a single 8 or 16 or 32 bit port or as individual port pins.
5.Targeted for high end market where performance is important.	5.Targeted for embedded market where performance is not critical.
6.Limited power saving options compared to micro-controllers.	6.Includes lot of power saving features.

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Difference between Harvard Architecture and Von-Neumann Architecture.

Harvard Architecture	Von-Neumann Architecture.
1.Separate buses for instruction and data fetching.	1.Single shared bus for instruction and data fetching.
2.Easier to pipeline , so high performance can be achieved .	2. Low performance compared to Harvard architecture
3.Comparatively high cost.	3. Cheaper
4.No memory alignment problems.	4. Allow self modifying codes.
5.Since data memory and program memory are stores physically in different locations, no chances for accidental corruption of program memory.	5. Since data memory and program memory are stores physically in the same chip , chances for accidental corruption of program memory.

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