An assembly language is a programming language that can be used to directly tell the computer what to do. An assembly language is almost exactly like the machine code that a computer can understand, except that it uses words in place of numbers. A computer cannot really understand an assembly program directly. However, it can easily change the program into machine code by replacing the words of the program with the numbers that they stand for. A program that does that is called an assembler.

Programs written in assembly language are usually made of instructions, which are small tasks that the computer performs when it is running the program.  They are called instructions because the programmer uses them to instruct the computer what to do.  The part of the computer that follows the instructions is the processor.

The assembly language of a computer is a low-level language, which means that it can only be used to do the simple tasks that a computer can understand directly. In order to perform more complex tasks, one must tell the computer each of the simple tasks that are part of the complex task. For example, a computer does not understand how to print a sentence on its screen. Instead, a program written in assembly must tell it how to do all of the small steps that are involved in printing the sentence.

Such an assembly program would be composed of many, many instructions, that together do something that seems very simple and basic to a human. This makes it hard for humans to read an assembly program. In contrast, a high-level programming language may have a single instruction such as PRINT "Hello, world!" that will tell the computer to perform all of the small tasks for you.

Development of assembly language
When computer scientists first built programmable machines, they programmed them directly in machine code, which is a series of numbers that instructed the computer what to do. Writing machine language was very hard to do and took a long time, so eventually assembly language was made. Assembly language is easier for a human to read and can be written faster, but it is still much harder for a human to use than a high-level programming language which tries to mimic human language.

Programming in machine code
To program in machine code, the programmer needs to know what each instruction looks like in binary (or hexadecimal). Although it is easy for a computer to quickly figure out what machine code means, it is hard for a programmer.  Each instruction can have several forms, all of which just look like a bunch of numbers to people. Any mistake that someone makes while writing machine code will only be noticed when the computer does the wrong thing.  Figuring out the mistake is hard because most people cannot tell what machine code means by looking at it. An example of what machine code looks like:
05 2A 00
This hexadecimal machine code tells an x86 computer processor to add 42 to the accumulator. It is very difficult for a person to read and understand it even if that person knows machine code.

Using assembly language instead
With assembly language, each instruction can be written as a short word, called a mnemonic, followed by other things like numbers or other short words. The mnemonic is used so that the programmer does not have to remember the exact numbers in machine code needed to tell the computer to do something. Examples of mnemonics in assembly language include add, which adds data, and mov, which moves data from one place to another.  Because 'mnemonic' is an uncommon word, the phrase instruction type or just instruction is sometimes used instead, often incorrectly. The words and numbers after the first word give more information about what to do. For instance, things following an add might be what two things to add together and the things following mov say what to move and where to put it.

For example, the machine code in the previous section (05 2A 00) can be written in assembly as:
 add ax,42

Assembly language also allows programmers to write the actual data the program uses in easier ways.  Most assembly languages have support for easily making numbers and text.  In machine code, each different type of number like positive, negative or decimal, would have to be manually converted into binary and text would have to be defined one letter at a time, as numbers.

Assembly language provides what is called an abstraction of machine code.  When using assembly, programmers do not need to know the details of what numbers mean to the computer, the assembler figures that out instead.  Assembly language actually still lets the programmer use all the features of the processor that they could with machine code. In this sense, assembly language has a very good, rare trait: it has the same ability to express things as the thing it is abstracting (machine code) while being much easier to use.  Because of this, machine code is almost never used as a programming language.

Disassembly and debugging
When programs are finished, they have already been transformed into machine code so that the processor can actually run them. Sometimes, however, if the program has a bug (mistake) in it, programmers will want to be able to tell what each part of the machine code is doing. Disassemblers are programs that help programmers do that by transforming the machine code of the program back into assembly language, which is much easier to understand. Disassemblers, which turn machine code into assembly language, do the opposite of assemblers, which turn assembly language into machine code.

Computer organization
An understanding of how computers are organized, how they seem to work at a very low level, is needed to understand how an assembly language program works. At the most simplistic level, computers have three main parts:

main memory or RAM which holds data and instructions,
a processor, which processes the data by executing the instructions, and
input and output (sometimes shortened to I/O), which allow the computer to communicate with the outside world and store data outside of main memory so it can get the data back later.

Main memory
In most computers, memory is divided up into bytes. Each byte contains 8 bits.  Each byte in memory also has an address which is a number that says where the byte is in memory. The first byte in memory has an address of 0, the next one has an address of 1, and so on. Dividing memory into bytes makes it byte addressable because each byte gets a unique address. Addresses of byte memories cannot be used to refer to a single bit of a byte. A byte is the smallest piece of memory that can be addressed.

Even though an address refers to a particular byte in memory, processors allow for using several bytes of memory in a row.  The most common use of this feature is to use either 2 or 4 bytes in a row to represent a number, usually an integer. Single bytes are sometimes also used to represent integers, but because they are only 8 bits long, they can only hold 28 or 256 different possible values. Using 2 or 4 bytes in a row raises the number of different possible values to be 216, 65536 or 232, 4294967296, respectively.

When a program uses a byte or a number of bytes in a row to represent something like a letter, number, or anything else, those bytes are called an object because they are all part of the same thing. Even though objects are all stored in identical bytes of memory, they are treated as though they have a 'type', which says how the bytes should be understood: either as an integer or a character or some other type (like a non-integer value). Machine code can also be thought of as a type that is interpreted as instructions. The notion of a type is very, very important because it defines what things can and can't be done to the object and how to interpret the bytes of the object. For instance, it is not valid to store a negative number in a positive number object and it is not valid to store a fraction in an integer.

An address that points to (is the address of) a multi-byte object is the address to the first byte of that object – the byte that has the lowest address. As an aside, one important thing to note is that you can't tell what the type of an object is - or even its size - by its address. In fact, you can't even tell what type an object is by looking at it. An assembly language program needs to keep track of which memory addresses hold which objects, and how big those objects are. A program that does so is type safe because it only does things to objects that are safe to do on their type. A program that doesn't will probably not work properly. Note that most programs do not actually explicitly store what the type of an object is, they just access objects consistently - the same object is always treated as the same type.

The processor
The processor runs (executes) instructions, which are stored as machine code in main memory. As well as being able to access memory for storage, most processors have a few small, fast, fixed-size spaces for holding objects that are currently being worked with. These spaces are called registers.   Processors usually execute three types of instructions, although some instructions can be a combination of these types. Below are some examples of each type in x86 assembly language.

Instructions that read or write memory
The following x86 assembly language instruction reads (loads) a 2-byte object from the byte at address 4096 (0x1000 in hexadecimal) into a 16-bit register called 'ax':

	mov ax, [1000h]

In this assembly language, square brackets around a number (or a register name) mean that the number should be used as an address to the data that should be used. The use of an address to point to data is called indirection. In this next example, without the square brackets, another register, bx, actually gets the value 20 loaded into it.

	mov bx, 20
Because no indirection was used, the actual value itself was put into the register.

If the operands (the things that come after the mnemonic), appear in the reverse order, an instruction that loads something from memory instead writes it to memory:

	mov [1000h], bx

Here, the memory at address 1000h gets the value of bx. If this example is executed right after the previous one, the 2 bytes at 1000h and 1001h will be a 2 byte integer with the value of 20.

Instructions that perform mathematical or logical operations
Some instructions do things like subtraction or logical operations like not:

The machine code example earlier in this article would be this in assembly language:

	add ax, 42

Here, 42 and ax are added together and the result is stored back in ax. In x86 assembly it is also possible to combine a memory access and mathematical operation like this:

	add ax, [1000h]
This instruction adds the value of the 2 byte integer stored at 1000h to ax and stores the answer in ax.

	or ax, bx
This instruction computes the or of the contents of the registers ax and bx and stores the result back into ax.

Instructions that decide what the next instruction is going to be

Usually, instructions are executed in the order they appear in memory, which is the order they are typed in the assembly code. The processor just executes them one after another.  However, in order for processors to do complicated things, they need to execute different instructions based on what the data they were given is. The ability of processors to execute different instructions depending on something's outcome is called branching.  Instructions that decide what the next instruction should be are called branch instructions.

In this example, suppose someone wants to calculate the amount of paint they will need to paint a square with a certain side length.  However, due to economy of scale the paint store will not sell them any less than amount of paint needed to paint a 100 x 100 square.

To figure out the amount of paint they will need to get based on the length of the square they want to paint, they come up with this set of steps:

subtract 100 from the side length
if the answer is less than zero, set the side length to 100
multiply the side length by itself

That algorithm can be expressed in the following code where ax is the side length.

	mov bx, ax
	sub bx, 100
	jge continue
	mov ax, 100
continue:
	mul ax

This example introduces several new things, but the first two instructions are familiar. They copy the value of ax into bx and then subtract 100 from bx.

One of the new things in this example is called a label, a concept found in assembly languages in general. Labels can be anything the programmer wants (unless it is the name of an instruction, which would confuse the assembler). In this example, the label is 'continue'. It is interpreted by the assembler as the address of an instruction. In this case, it is the address of mult ax.

Another new concept is that of flags.  On x86 processors, many instructions set 'flags' in the processor that can be used by the next instruction to decide what to do.  In this case, if bx was less than 100, sub will set a flag that says the result was less than zero.

The next instruction is jge which is short for 'jump if greater than or equal to'. It is a branch instruction. If the flags in the processor specify that the result was greater than or equal to zero, instead of just going to the next instruction the processor will jump to the instruction at the continue label, which is mul ax.

This example works fine, but it is not what most programmers would write.  The subtract instruction set the flag correctly, but it also changes the value it operates on, which required the ax to be copied into bx. Most assembly languages allow for comparison instruction that do not change any of the arguments they are passed, but still set the flags properly and x86 assembly is no exception.

	cmp ax, 100
	jge continue
	mov ax, 100
continue:
	mul ax

Now, instead of subtracting 100 from ax, seeing if that number is less than zero, and assigning it back to ax, ax is left unchanged. The flags are still set the same way, and the jump is still taken in the same situations.

Input and output
While input and output are a fundamental part of computing, there is no one way they are done in assembly language. This is because the way I/O works depends on the set up of the computer and the operating system its running, not just what kind of processor it has.  In the example section below, the Hello World example uses MS-DOS operating system calls and the example after it uses BIOS calls.

It is possible to do I/O in assembly language.  Indeed, assembly language can generally express anything that a computer is capable of doing. However, even though there are instructions to add and branch in assembly language that will always do the same thing there are no instructions in assembly language that always do I/O.

The important thing to note is that the way that I/O works is not part of any assembly language because it is not part of how the processor works.

Assembly languages and portability

Even though assembly language is not directly run by the processor - machine code is, it still has a lot to do with it.  Each processor family supports different features, instructions, rules for what the instructions can do, and rules for what combination of instructions are allowed where. Because of this, different types of processors still need different assembly languages.

Because each version of assembly language is tied to a processor family, it lacks something called portability. Something that has portability or is portable can be easily transferred from one type of computer to another. While other types of programming languages are portable, assembly language, in general, is not.

Assembly language and high-level languages

Although assembly language allows for an easy way to use all the processor's features, it is not used for modern software projects for several reasons:

 It takes a lot of effort to express a simple program in assembly.
 Although not as error-prone as machine code, assembly language still offers very little protection against errors. Almost all assembly languages do not enforce type safety.
 Assembly language does not promote good programming practices like modularity.
 While each individual assembly language instruction is easy to understand, it is hard to tell what the intent of the programmer was who wrote it. In fact, the assembly language of a program is so hard to understand that companies do not worry about people dissassembling (getting the assembly language of) their programs.

As a result of these drawbacks, high-level languages like Pascal, C, and C++ are used for most projects instead.  They allow programmers to express their ideas more directly instead of having to worry about telling the processor what to do every step of the way. They're called high-level because the ideas the programmer can express in the same amount code are more complicated.

Programmers writing code in compiled high level languages use a program called a compiler to transform their code into assembly language.  Compilers are much harder to write than assemblers are. Also, high-level languages do not always allow programmers to use all the features of the processor. This is because high-level languages are designed to support all processor families. Unlike assembly languages, that only support one type of processor, high-level languages are portable.

Even though compilers are more complicated than assemblers, decades of making and researching compilers has made them very good. Now, there is not much reason to use assembly language anymore for most projects, because compilers can usually figure out how to express programs in assembly language as well or better than programmers.

Example programs

A Hello, world! program written in x86 assembly:
adosseg
.model small
.stack 100h

.data
hello_message db 'Hello, World!',0dh,0ah,'$'

.code
main  proc
      mov    ax,@data
      mov    ds,ax

      mov    ah,9
      mov    dx,offset hello_message
      int    21h

      mov    ax,4C00h
      int    21h
main  endp
end   main.

A function that prints a number to the screen using BIOS interrupts written in NASM x86 assembly. Modular code is possible to write in assembly, but it takes extra effort. Note that anything that comes after a semicolon on a line is a comment and is ignored by the assembler. Putting comments in assembly language code is very important because large assembly language programs are so hard to understand.
; void printn(int number, int base);

printn:
	push	bp
	mov	bp, sp
	push	ax
	push 	bx
	push	cx
	push	dx
	push	si

	mov	si, 0
	mov	ax, [bp + 4]	; number
	mov	cx, [bp + 6]	; base

gloop:	inc	si		; length of string
	mov	dx, 0		; zero dx
	div	cx		; divide by base
	cmp	dx, 10		; is it ge 10?
	jge	num
	add	dx, '0'		; add zero to dx
	jmp	anum
num:	add	dx, ('A'- 10)	; hex value, add 'A' to dx - 10.
anum:	push	dx		; put dx onto stack.
	cmp	ax, 0		; should we continue?
	jne	gloop

	mov	bx, 7h		; for interrupt
tloop:	pop	ax		; get its value
	mov	ah, 0eh		; for interrupt
	int	10h		; write character
	dec	si		; get rid of character
	jnz	tloop

	pop	si
	pop	dx
	pop	cx
	pop	bx
	pop	ax
	pop	bp
	ret	4

Books
 Michael Singer, PDP-11. Assembler Language Programming and Machine Organization, John Wiley & Sons, NY: 1980.
 Peter Norton, John Socha, Peter Norton's Assembly Language Book for the IBM PC, Brady Books, NY: 1986.
 Dominic Sweetman: See MIPS Run. Morgan Kaufmann Publishers, 1999.
 John Waldron: Introduction to RISC Assembly Language Programming. Addison Wesley, 1998.
 Jeff Duntemann: Assembly Language Step-by-Step. Wiley, 2000.
 Paul Carter: PC Assembly Language. Free ebook, 2001.Website
 Robert Britton: MIPS Assembly Language Programming. Prentice Hall, 2003.
 Randall Hyde: The Art of Assembly Language. No Starch Press, 2003. Draft versions available online  as PDF and HTML
 Jonathan Bartlett: Programming from the Ground Up. Bartlett Publishing, 2004. Available online as PDF and as HTML
 ASM Community Book "An online book full of helpful ASM info, tutorials and code examples" by the ASM Community

Software
 MenuetOS - Operating System written entirely in 64-bit assembly language
 SB-Assembler for most 8-bit processors/controllers
 GNU lightning, a library that generates assembly language code at run-time which is useful for Just-In-Time compilers
 WinAsm Studio, The Assembly IDE - Free Downloads, Source Code , a free Assembly IDE, a lot of open source programs to download and a popular Board
 The Netwide Assembler
 GoAsm - a free component "Go" tools: support 32-bit & 64-bit Windows programming

Other websites
http://www.atariarchives.org/mlb/introduction.php
http://www.swansontec.com/sprogram.htm
 The ASM Community, a great ASM programming resource including a Messageboard and an ASM Book
 Intel Assembly 80x86 CodeTable (a cheat sheet reference)
 Unix Assembly Language Programming
 PPR: Learning Assembly Language
 Assembly Language Programming Examples
 Typed Assembly Language (TAL)
 Authoring Windows Applications In Assembly Language
 Information on Linux assembly programming
 Terse: Algebraic Assembly Language for x86
 Iczelion's Win32 Assembly Tutorial
 IBM z/Architecture Principles of Operation IBM manuals on mainframe machine language and internals.
 IBM High Level Assembler IBM manuals on mainframe assembler language.
 Assembly Optimization Tips by Mark Larson
 Mainframe Assembler Forum
 NASM Manual
 Experiment with Intel x86/x64 operating modes with assembly
 Build yourself an assembler (eniAsm project)  and various assembly articles and tutorials
 Encoding Intel x86/IA-32 Assembler Instructions

Programming languages

Assembly language


A topological space is a space studied in topology, the mathematics of the structure of shapes. Roughly, it is a set of things (called points) along with a way to know which things are close together.

More precisely, a topological space has a certain kind of set, called open sets. Open sets are important because they allow one to talk about points near another point, called a neighbourhood of the point. A neighbourhood of a point is simply an open set containing that point. If one did not have the concept of open sets, one cannot define neighbourhoods in a good way. If one tries to define a neighbourhood of a point as any set containing that point, it might just include that point and that point only, not any points near it, or points far away.
We also have the concept of closed sets, which are complements of open sets. That is, all of the points not belonging to a certain open sets forms a closed set.

Open sets must follow certain rules so that they match our ideas of nearness. The union of any number of open sets must be open, and the union of a finite number of closed sets must be closed. (The second rule only works for a finite number of closed sets. That is because in many cases a set containing a single point is closed. Any set is made of points. If the second rule applied to an infinite number of closed sets, then every set would be closed.) As a special case, the set containing every point is both open and closed. The set containing no points is also both open and closed.

A set of points can have many different definitions of what an open set is. One can think of only certain sets as open, or more sets as open. One might even consider every set to be open. The same set with different definitions of open sets form different topological spaces.

Topology

Topological space


A laugh is a way of showing happiness. It is a  vocal sound which a person makes when something is funny, like a joke, or a tickle.

Sometimes people laugh when they are not happy. When people are ashamed or embarrassed, sometimes they react by laughing.

There are different ways to laugh. A person can laugh using mostly their voice, mostly their throat, or mostly their nose.

You can write a laugh in different ways. Some people write "ha ha ha", or "he he he", or "hehe". If they are on the internet, they also use "LOL". "LOL" does not sound like a laugh, but it stands for Laughing Out Loud.

Human babies first laugh at the age of around three or four months, usually as an expression of surprise. Babies' laughter often produces a positive response in adults who will involuntarily copy the child. Video footage, on the YouTube site, of babies laughing was shown to Queen Elizabeth II during her visit, on 16 October 2008, to the Google headquarters, where both she and her husband the Duke of Edinburgh were reduced to 'fits of giggles'.

References

Human communication

Laugh


Ammunition, often called ammo, comes from the French word la munition. At first it meant all items used for war. This was from the Latin word munire (to provide). It now is used only for bullets and other projectiles that are thrown at the enemy by guns, and the gunpowder or other propellant that throws the projectiles. The group word for all types of ammunition is munitions. This means any explosive thing that can be used in combat and includes bombs, missiles, warheads, and mines (landmines, naval mines, and claymore mines). These are made in munitions factories.

Ammunition is mainly used to attack a target. Ammunition can include flares and incendiary devices that start fires.  Since the invention of the cartridge, ammunition has come to mean the putting of a projectile - the item that is sent to hit the target, and its propellant - the chemical that creates the force, into a single package.

Ammunition is a complex subject.  It includes many different weapons used by people, such as explosives and propellants, cartridges, high explosive projectiles (HE), warheads, special shells to attack armour and aircraft, carrier projectiles, fuses, mortar ammunition, small arms (revolver and pistol) ammunition, grenades, mines, flares, improved conventional munitions, and computer guided munition.

References

Explosives

Ammunition


Basa Latin atawa Latén baheulana mangrupa basa asli nu dipaké di wewengkon sabudeureun Roma nu disebut Latium. Boga pangaruh gedé nalika jadi basa formal Karajaan Romawi.

Sadaya Basa Romawi diturunkeun tina basa Latin, sarta loba kekecapan nu asalna tina kecap Latin kapanggih ogé dina basa-basa modérn séjénna kayaning basa Inggris. Leuwih ti éta, di dunya Kulon, basa Latin geus jadi lingua franca, basa nu diteuleuman sarta dilarapkeun pikeun kaperluan ilmiah sarta pulitik, salila leuwih ti sarébu taun, nu kalindih ku basa Prancis dina abad ka-18 sarta basa Inggris ahir abad ka-19. Kiwari jadi basa resmi Garéja Katolik Roma, kaasup salaku basa resmi nasional Kota Vatikan. Basa Latin ogé masih dipaké, bareng jeung basa Yunani, pikeun nangtukeun ngaran nu dipaké dina klasifikasi ilmiah mahluk hirup.

Fitur Utama

Latin has an extensive flectional system, which mainly operates by appending strings to a fixed stem. Inflection of nouns and adjectives is termed "declension", that of verbs, "conjugation". There are five declensions of nouns, and four conjugations for verbs. The six noun forms (or "cases") are:
 nominative (subjects and predicate nominatives),
 genitive (relation, often possession),
 dative (indirect objects),
 accusative (direct objects, some prepositional phrases),
 ablative (separation, source, cause, or instrument),
 vocative (direct address).

In addition, there exists in some nouns a locative case used to express place (normally expressed by the ablative with a preposition such as IN), but this hold-over from Indo-Européan is only found in the names of lakes, cities, towns, similar locales, and a few other words.

Basa Latin jeung Romans

Saruntagna Karajaan Romawi, basa Latin robah jadi rupa-rupa basa Romans. These were for many centuries only spoken languages, Latin being still used for writing. (E.g. Latin was the official language of Portugal until 1296 when it was replaced by Portuguese.)

Actually the Romance languages are not derived from Classical Latin but rather from the spoken Vulgar Latin. Latin and Romance differ (for example) in that Romance had distinctive stress wheréas Latin had distinctive length of vowels. In Italian and Sardo logudorese, there is distinctive length of consonants and stress, in Spanish only distinctive stress, and in French even stress is no longer distinctive.

Another major distinction between Romance and Latin is that Romance languages, excluding Romanian, have lost their case endings in most words except for some pronouns. Romanian still has five cases (though the ablative is no longer represented).

Basa Latin jeung basa Inggris

Tatabasa Inggris teu sacara langsung diturunkeun tina tatabasa Latin. Attempts to maké English grammar fit Latin rules — such as the contrived prohibition against the split infinitive — have not worked successfully in regular usage. However, as many as half the words in English come to us through Latin, including many words of Greek origin first adopted by the Romans, not to mention the thousands of French, Spanish, and Italian words of Latin origin that have also enriched English.

Nalika abad ka-16 nepi ka abad ka-18, panulis-panulis Inggris nyipta loba pisan kecap-kecap anyar nu diturunkeun tina akar kecap basa Latin jeung Yunani. Kecap-kecap ieu, euyeub ku rasa jeung harti. Loba kecap-kecapna nu kungsi dipaké terus kapopohokeun, tapi sabagian mah aya kénéh, kayaning imbibe, extrapolate, jeung inebriation.

Tempo ogé

Ngeunaan basa Latin
 Tatabasa Latin
 Foném Latin
 Latin declension
 Konjugasi Latin
 Léxikon Latin
 ablative absolute
 susunan aksara Latin

Ngeunaan sastra Latin
 Sastra Latin
 Pabukon Klasik Loeb
 Latin proverbs
 Daptar frase Latin
 Daptar Latin proverbs
 Brocard
 Daptar kecap-kecap Latin atawa Yunani nu ilahar dipaké dina ngaran sistimatis
 Carmen Possum

Jejer séjén nu patali
 Kakaisaran Romawi
 Latin Anyar

Tumbu kaluar
 Wikipédia Latin
 The Perseus Project has many useful pages for the study of classical languages and literatures, including an interactive Latin dictionary.
 Ethnologue report for Latin
 Free online courses in Latin
 http://www.sprachprofi.de.vu/latin
 http://wikibooks.org/wiki/Latin
 The Latin Library contains many Latin etexts
 Textkit has Latin textbooks and etexts.
 Latin - English Dictionary: from Webster's Rosetta Edition.
 Language reference  Cross-foreign-language lexicon powered by its own séarch engine. All cross combinations between Latin and French, German, Italian, Spanish.

Basa nu geus lastari
Basa Itali
Romawi Kuna
Latin

Basa Latén


The lung is an organ in many vertebrates (animals having a spine, or backbone). It takes blood oxygen from the air, and expels carbon dioxide. Most vertebrates with lungs have two of them.

In animals, the lungs are the area where gas exchange takes place. Without gas exchange, oxygen would not pass into the blood from the lungs so the body cells would not be able to receive the oxygen needed for respiration.

The alveoli are moist to allow oxygen to move from the lung through the alveoli into blood vessels and red blood cells. Carbon dioxide passes from the blood into the alveoli. The oxygen-filled blood goes back to the heart and the carbon dioxide in the alveoli is pushed out of the lungs and into the air we breathe out.

Bird lung
Birds lungs are smaller than mammal lungs, and do not have alveoli, instead they have millions of para-bronchi. These para-bronchi end up in tiny capillaries or very small blood vessels and they pass close to the body's blood vessels, so diffusion can occur and the oxygen and carbon dioxide is exchanged. The oxygen and carbon dioxide in birds lungs are continuously  diffused into and out of the blood, not like in mammals where diffusion can only happen in the alveoli. Air does not go into and back out of the lungs as in mammals. Instead, muscular air sacs push the air forward through bird lungs.

Reptile lung
Reptile lungs open and close because of the ribs surrounding them pressing down on them and then opening up with the help of muscles. The liver is also attached to the bottom of the lungs and when a muscle which is attached to the liver pulls, the liver moves away from the lungs and pulls them, making them bigger.

Amphibian lung
Frog lungs are very simple compared to most other lungs, they are simply balloons, with moist outsides allowing for diffusion. But frogs do not move around much and so do not need lots of oxygen, but they can also take in oxygen through their moist outer skin if a big demand of oxygen is needed (e.g. Fight or flight response)

Other websites
 A revision site directed towards IGSCE students
 A to Z list of diseases of the Lung
 List of Lung Cancer information sites
 In depth articles on the lung
 In depth article on the anatomy of a lung

Anatomy of the respiratory system

Lung


Cellular respiration is what cells do to break up sugars to get energy they can use. Cellular respiration takes in food and uses it to create ATP, a chemical which the cell uses for energy.

Usually, this process uses oxygen, and is called aerobic respiration. It has four stages known as glycolysis, Link reaction, the Krebs cycle, and the electron transport chain. This produces ATP which supplies the energy that cells need to do work.

When they do not get enough oxygen, the cells use anaerobic respiration, which does not use oxygen.  However, this process produces lactic acid, and is not as efficient as when oxygen is used.

Aerobic respiration, the process that does use oxygen, produces much more energy and does not produce lactic acid.  It also produces carbon dioxide as a waste product, which then enters the circulatory system.  The carbon dioxide is taken to the lungs, where it is exchanged for oxygen.

The simplified formula for aerobic cellular respiration is:

C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy (as ATP)
The word equation for this is:Glucose (sugar) + Oxygen → Carbon dioxide + Water + Energy (as ATP)

Aerobic cellular respiration has four stages. Each is important, and could not happen without the one before it. The steps of aerobic cellular respiration are:
 Glycolysis (the break down of glucose)
 Link reaction
 Krebs cycle
 Electron transport chain, or ETC

Glycolysis

In glycolysis, glucose in the cytoplasm is broken into two molecules of pyruvate. Ten enzymes are needed for the ten intermediate compounds in this process.
 Two energy-rich ATP kick-start the process.
 At the end are two pyruvate molecules, plus
 Substrate level - Four molecules of ATP are made in reaction number 7 & 10
 In cells which use oxygen, the pyruvate is used in a second process, the Krebs cycle, which produces more ATP molecules.

Productivity of the cycle
Biology textbooks often state that 38 ATP molecules can be made per oxidised glucose molecule during cellular respiration (two from glycolysis, two from the Krebs cycle, and about 34 from the electron transport chain). However, the process actually makes less energy (ATP) because of losses through leaky membranes. Estimates are 29 to 30 ATP per glucose.

Aerobic metabolism is about (see sentence above) 15 times more efficient than anaerobic metabolism. Anaerobic metabolism yields 2 mol ATP per 1 mol glucose. They share the initial pathway of glycolysis but aerobic metabolism continues with the Krebs cycle and oxidative phosphorylation. The post glycolytic reactions take place in the mitochondria in eukaryotic cells, and in the cytoplasm in prokaryotic cells.

Link reaction

Pyruvate from glycolysis is actively pumped  into mitochondria. One carbon dioxide molecule and one hydrogen molecule are removed from the pyruvate (called oxidative decarboxylation) to produce an acetyl group, which joins to an enzyme called CoA to form acetyl CoA. This is essential for the Krebs cycle.

Krebs cycle

Acetyl CoA joins with oxaloacetate to form a compound with six carbon atoms. This is the first step in the ever-repeating Krebs cycle. Because two acetyl-CoA molecules are produced from each glucose molecule, two cycles are required per glucose molecule. Therefore, at the end of two cycles, the products are: two ATP, six NADH, two FADH, and four CO2. The ATP is a molecule which carries energy in chemical form to be used in other cell processes.  This process is also known as the TCA cycle (Tricarboxylic (try-car-box-ILL-ick) acid cycle), the citric acid cycle, or the Krebs cycle after the biochemist who elucidated its reactions.

Electron transport chain (ETC)

This is where most of the ATP is made. All of the hydrogen molecules which have been removed in the  steps before (Krebs cycle, Link reaction) are pumped inside the mitochondria using energy that electrons release. Eventually, the electrons powering the pumping of hydrogen into the mitochondria mix with some hydrogen and oxygen to form water and the hydrogen molecules stop being pumped.

Eventually, the hydrogen flows back into the cytoplasm of the mitochondria through protein channels. As the hydrogen flows, ATP is made from ADP and phosphate ions.

:

References

Related pages
Metabolism
Photosynthesis

Metabolism

Cellular respiration


Echidna (Greek: from "Snake") is a monster of Greek mythology, half woman, half serpent. Her parents were either the sea deities Phorcys and Ceto (according to Hesiod's Theogony) or Tartarus and Gaia (in the account of the mythographer Apollodorus); in Hesiod, Tartarus and Gaia are the parents of Echidna's husband, Typhon. Among Echidna's progeny by the 100-headed Typhon, were Ladon (the dragon who protected the Golden Apples of the Hesperides), another dragon who protected the Golden Fleece, the Hydra, the goatlike Chimera, and the infernal hounds Orthus and Cerberus. The Sphinx and the Nemean lion, both sired by Orthus, were also among her offspring.

Greek legendary creatures

Echidna (mythology)


Primary colors (or primary colours in Commonwealth English) are sets of colors that can be combined to make a useful range of colors. The primary colors are those which cannot be created by mixing other colors in a given color space.

For subtractive combination of colors, as in mixing of pigments or dyes for printing, the CMYK set of primaries is often used. In this system the primary colors are cyan, magenta,and yellow. Other sets include the RYB system of red, yellow, blue, especially used by artists.

For additive combination of colors, as in overlapping projected lights or in television and computer screens, the primary colors normally used are red, green, and blue.

Biological basis
Primary colors are not a fundamental property of light but are related to the physiological response of the eye to light (the way the eye works). For humans, three primary colors are usually used, since human color vision is trichromatic.

Fundamentally, light is a continuous spectrum of the wavelengths that can be detected by the human eye, an infinite-dimensional stimulus space. However, the human eye normally contains only three types of color receptors, called cone cells. Each color receptor respond to different ranges of the color spectrum. Humans and other species with three such types of color receptors are known as trichromats.

The additive primaries are red, green,
and blue. Because of the response curves of the three different color receptors in
the human eye, these colors are optimal in the sense that the largest range
of colors — a gamut — visible by humans can be generated by mixing light of these colours.
Additive mixing of red and green light, produce shades of yellow or orange. Mixing green and blue produces shades of cyan, and mixing red and blue produces shades of purple and magenta. Mixing equal proportions of the additive primaries results in shades of grey; when all three colors are fully saturated, the result is white. The color space that is generated is called the RGB ("red, green, blue") color space.

Subtractive primaries

Media that use reflected light and colorants to produce colors are using the subtractive color method of color mixing. In the printing industry, to produce the varying colors, apply the subtractive primaries yellow, cyan, and magenta together in varying amounts. Subtractive color works best when the surface or paper, is white, or close to it.

Mixing yellow and cyan produces shades of green; mixing yellow with magenta produces shades of red, and mixing magenta with cyan produces shades of blue. In theory, mixing equal amounts of all three pigments should produce shades of grey, resulting in black when all three are fully saturated, but in practice they tend to produce muddy brown colors. For this reason, a fourth "primary" pigment, black, is often used in addition to the cyan, magenta, and yellow colors.

The color space generated is the so-called CMYK color space. The abbreviation stands for "Cyan, Magenta, Yellow, and Black" — K stands for "Kohle" (German for coal) and is used to represent black as 'B' could be confused with 'Blue'.

In practice, mixtures of actual materials like paint tend to be less precise. Brighter, or more specific colors can be created using natural pigments instead of mixing, and natural properties of pigments can interfere with the mixing. For example, mixing magenta and green in acrylic creates a dark cyan - something which would not happen if the mixing process were perfectly subtractive.

Reference

Color

Primary color


Camille Saint-Saens (French: Camille Saint-Saëns) (born Paris 9 October 1835, died Algiers, 16 December 1921) was a French composer, pianist and organist. He was one of the greatest composers of his day. He composed lots of music of different kinds. Among his best works are his Symphony no 3 (with organ) , Piano Concerto no 2, Violin Concerto no 3, Cello Concerto no 1, the opera Samson and Delilah and the Danse Macabre. His most popular work, however, is the Carnival of the Animals. Saint-Saens hated being thought of as "the composer of the Carnival of the Animals". He said he had only written it for a bit of fun and he did not want anyone to perform it. Today it still remains one of the most popular pieces for children.

Life
Three months after Saint-Saens was born his father died. Saint-Saens was often ill with tuberculosis when he was very small and this carried on throughout his life. He was brought up by his mother and his aunt. this illness still didn't hold Saint-Saens back. at the age of two his aunt taught him the piano. When he was ten he played piano concertos by Beethoven and Mozart at a public concert, playing everything from memory. He was very good at school and was interested in lots of subjects including science and philosophy. In 1858 he published some duets for harmonium and piano and he used the money to buy a telescope.

He studied music at the Paris Conservatoire and was a brilliant student, although he did not win the Prix de Rome. He soon became known as a composer, pianist and organist and he made many friends, among them Gounod, Berlioz and Rossini. Liszt thought he was the greatest organist in the world. Like Liszt, Saint-Saëns was often very kind to other composers and helped them to become known by playing and conducting their music. He was the first person to conduct Liszt's symphonic poems in France. He himself wrote symphonic poems such as Le Rouet d'Omphale (1871) and Danse Macabre (1874). The idea of music which describes a story was quite a new idea at that time. He also helped people to like Bach whose music had been forgotten for a long time.

In the 1860s his fame spread and he also did some teaching at the École Niedermeyer which educated young musicians for church music. His pupils included Faure, Messager and Gigout who all became lifelong friends. He also founded the Société Nationale de Musique which helped new music to be performed. Faure, Cesar Franck and Lalo were all members. The society gave first performances of works by Saint-Saens, Chabrier, Debussy, Dukas and Ravel and others.

Saint-Saens married a 19-year-old girl. The marriage was not a success. They had two sons who died within six weeks of one another: the baby from an illness and the two-year-old from falling out of a fourth floor window. Saint-Saens blamed his wife and they eventually divorced.

For many years Saint-Saens travelled all over the world as a famous musician. Eventually he became less popular in France, but in England and the United States he was still very much admired. He played for Queen Victoria and spent some time studying original manuscripts of Handel in the library of Buckingham Palace. He was awarded the title of Doctor by the Universities of Oxford and Cambridge and was made a Commander of the Victorian Order because he had composed a march for the coronation of King Edward VII in 1902. He died in Algiers in 1921. His funeral was in the cathedral there, and his body was then taken back to Paris where he was given a state funeral at the church of Madeleine.

His music
Saint-Saens was more famous in the concert hall than he was in the theatre. He wrote 13 operas, but only one of them is still regularly performed: Samson et Dalila (Samson and Delilah). One of the arias from this opera, Mon cœur s'ouvre à ta voix, is especially famous.

Saint-Saens wrote many concertos, symphonies, sonatas and chamber music. He often uses the style of dance music and creates a happy atmosphere by repeating certain patterns. His music is late Romantic, but based on the classical traditions rather than following the style of Wagner like many other French composers were doing at the time.
 Camille Saint-Saëns' "Organ-Symphony" (together with works of Debussy and Fauré). Spanish Radio and Television Symphony Orchestra.

20th-century French composers
Romantic composers
French pianists
French organists
1835 births
1921 deaths

Camille Saint-Saëns


Celestial navigation is a method of navigation where a person figures out their location and direction using the stars in the night sky. It has been used by sailors to help them find their way in the night. They look for familiar stars or constellations, which will help them find their way.

Celestial navigation involves comparing the angle of certain stars to other stars and how high they are above the Earth's horizon. By doing this, a person can find their longitude.

Navigation
Astronomy

Celestial navigation


Transistor nyaéta parangkat sémikonduktor nu miboga tilu terminal, bisa digunakeun keur nguatkeun, nyaklar, nytabilkeun voltase, modulasi sinyal, sarta loba deui kagunaan séjénna. Transistor mangrupa blok wangunan dasar tina integrated circuit (IC) analog atawa digital -- sirkuit nu dipaké ngoperasikeun komputer, telepon sélulér, jeung éléktronika modéren séjénna.

Pangwanoh

Kecap transistor mangrupa kecap pondokna tina transfer varistor. Dingaranan kitu sabab hiji sinyal asupan digunakeun keur ngarobah résistansi dina jalur sinyal kaluaran (varistor nyaéta variable resistor).

Transistor kabagi jadi dua kategori utama: bipolar junction transistor (BJT) jeung field effect transistor (FET). Panerapan arus dina BJT jeung tegangan dina FET antara asupan jeung terminal common bakal nambah konduktivitas antara terminal common jeung kaluaran, antukna arus pangaturannana ngalir di antarana.
Keur leuwih jéntré ngeunaan operasi dua tipe transistor ieu, tempo field effect transistor jeung bipolar junction transistor.

Dina sirkuit analog, transistor dipaké dina panguat, (panguat arus saarah, panguat sora, panguat frékuénsiradio), jeung Sumber daya nu diregulasi linier. Transistor ogé dipaké dina sirkuit digital nu mana fungsina minangka sakelar. Sirkuit digital ngawengku lawang logika, random access memory (RAM), mikroprosesor, jeung pamroses sinyal digital (digital signal processors) (DSP).

Pentingna transistor
The transistor is considered by many to be one of the gréatest inventions in modérn history, ranking in importance with the printing press, automobile and telephone. It is the key active component in practically all modérn electronics. Its importance in today's society rests on its ability to be mass produced using a highly automated process (fabrication) that achieves vanishingly low per-transistor costs.

Although millions of individual (known as discrete) transistors are still used, the vast majority of transistors are fabricated into integrated circuits (also called microchips or simply chips) along with diodes, resistors, capacitors and other electronic components to produce complete electronic circuits. A logic gate comprises about twenty transistors wheréas an advanced microprocessor, as of 2006, can use as many as 1.7 billion transistors (MOSFETs)  .

The transistor's low cost, flexibility and reliability have made it a universal device for non-mechanical tasks, such as digital computing. Transistorized circuits have replaced electromechanical devices for the control of appliances and machinery as well. It is often less expensive and more effective to use a standard microcontroller and write a computer program to carry out a control function than to design an equivalent mechanical control function.

Because of the low cost of transistors and hence digital computers, there is a trend to digitize information. With digital computers offering the ability to quickly find, sort and process digital information, more and more effort has been put into making information digital. As a result, today, much media data is delivered in digital form, finally being converted and presented in analog form by computers. Aréas influenced by the Digital Revolution include television, radio, and newspapers.

Sajarah

The first patents for the transistor principle were registered in Germany in 1928 by Julius Edgar Lilienfeld. In 1934 German physicist Dr. Oskar Heil patented the field-effect transistor. It is not cléar whether either design was ever built, and this is generally considered unlikely.

On 22 December 1947 William Shockley, John Bardeen and Walter Brattain succeeded in building the first practical point-contact transistor at Bell Labs. This work followed from their war-time efforts to produce extremely pure germanium "crystal" mixer diodes, used in radar units as a frequency mixer element in microwave radar receivers. éarly tube-based technology did not switch fast enough for this role, léading the Bell téam to use solid state diodes instéad. With this knowledge in hand they turned to the design of a triode, but found this was not at all éasy. Bardeen eventually developed a new branch of surface physics to account for the "odd" behaviour they saw, and Bardeen and Brattain eventually succeeded in building a working device.

Bell Telephone Laboratories needed a generic name for the new invention: "Semiconductor Triode", "Solid Triode", "Surface States Triode", "Crystal Triode" and "Iotatron" were all considered, but "transistor," coined by John R. Pierce, won an internal ballot. The rationale for the name is described in the following extract from the company's Technical Memoranda calling for votes:

Bell put the transistor into production at Western Electric in Allentown, Pennsylvania. They also licensed it to a number of other electronics companies, including Texas Instruments, who produced a limited run of transistor radios as a sales tool. Another company liked the idéa and also decided to take out a license, introducing their own radio under the brand name Sony. éarly transistors were "unstable" and only suitable for low-power, low-frequency applications, but as transistor design developed, these problems were slowly overcome. Over the next two decades, transistors gradually replaced the éarlier vacuum tubes in most applications and later made possible many new devices such as integrated circuits and personal computers.

Shockley, Bardeen and Brattain were honored with the Nobel Prize in Physics "for their researches on semiconductors and their discovery of the transistor effect". Bardeen would go on to win a second Nobel in physics, one of only two péople to receive more than one in the same discipline, for his work on the exploration of superconductivity.

In August 1948 German physicists Herbert F. Mataré (1912– ) and Heinrich Walker (ca. 1912–1981), working at Compagnie des Freins et Signaux Westinghouse in Paris, France applied for a patent on an amplifier based on the minority carrier injection process which they called the "transistron." Since Bell Labs did not maké a public announcement of the transistor until June 1948, the transistron was considered to be independently developed. Mataré had first observed transconductance effects during the manufacture of germanium duodiodes for German radar equipment during WWII. Transistrons were commercially manufactured for the French telephone company and military, and in 1953 a solid-state radio receiver with four transistrons was demonstrated at the Düsseldorf Radio Fair.

Tipe

|- align = "center"
|  || PNP ||  || P-channel
|- align = "center"
|  || NPN ||  || N-channel
|- align = "center"
| BJT || || JFET ||

Transistors are categorized by:
 Semiconductor material: germanium, silicon, gallium arsenide, silicon carbide
 Structure: BJT, JFET, IGFET (MOSFET), IGBT, "other types"
 Polarity: NPN, PNP, N-channel, P-channel
 Maximum power rating: low, medium, high
 Maximum operating frequency: low, medium, high, radio frequency (RF), microwave (The maximum effective frequency of a transistor is denoted by the term , an abbreviation for "frequency of transition." The frequency of transition is the frequency at which the transistor yields unity gain).
 Application: switch, general purpose, audio, high voltage, super-beta, matched pair
 Physical packaging: through hole metal, through hole plastic, surface mount, ball grid array

Thus, a particular transistor may be described as: silicon, surface mount, BJT, NPN, low power, high frequency switch.

Bipolar junction transistor
The bipolar junction transistor (BJT) was the first type of transistor to be mass-produced. Bipolar transistors are so named because they conduct by using both majority and minority carriers. The three terminals are named emitter, base and collector. Two p-n junctions exist inside a BJT: the base/collector junction and base/emitter junction. The BJT is commonly described as a current-operated device because the emitter/collector current is controlled by the current flowing between base and emitter terminals. Unlike the FET, the BJT is a low input-impedance device. The BJT has a higher transconductance than the FET. Bipolar transistors can be made to conduct with light (photons) as well as current. Devices designed for this purpose are called phototransistors.

Field-effect transistor
The field-effect transistor (FET), sometimes called a unipolar transistor, uses either electrons (N-channel FET) or holes (P-channel FET) for conduction. The three main terminals of the FET are named source, gate and drain. On some FETs a fourth connection to the body (substrate) is provided, but normally the body is connected internally to the source.

A voltage applied between the gate and source controls the current flowing between the source and drain. In FETs the source/ drain current flows through a conducting channel néar the gate. This channel connects the source region to the drain region. The channel conductivity is varied by the electric field generated by the voltage applied between the gate/source terminals. In this way the current flowing between the source and drain is controlled. Like bipolar transistors, FETs can be made to conduct with light (photons) as well as voltage. Devices designed for this purpose are called phototransistors.

FETs are divided into two families: junction FET (JFET) and insulated gate FET (IGFET). The IGFET is more commonly known as metal-oxide-semiconductor FET (MOSFET), from their original construction as a layer of metal (the gate), a layer of oxide (the insulation), and a layer of semiconductor. Unlike IGFETs, the JFET gate forms a PN diode with the channel which lies between the source and drain. Functionally, this makes the N-channel JFET the solid state equivalent of the vacuum tube triode which, similarly, forms a diode between its grid and cathode. Also, both devices operate in the depletion mode, they both have a high input impedance, and they both conduct current under the control of an input voltage.

MESFETs are JFETs, in which the reverse biased PN junction is replaced by a semiconductor-metal Schottky-junction. These, and the HEMFETs (high electron mobility FETs), in which a two-dimensional electron gas with very high carrier mobility is used for charge transport, are especially suitable for use at very high frequencies (microwave frequencies; several GHz).

FETs are further divided into depletion-mode and enhancement-mode types. Mode refers to the polarity of the gate voltage with respect to the source at the threshold of conduction. For N-channel depletion-mode FETs the gate is negative with respect to the source while for N-channel enhancement-mode FETs the gate is positive, at the threshold of conduction. For both modes, if the gate voltage is made more positive the source/drain current will incréase. For P-channel devices the polarities are reversed. Néarly all JFETs are depletion-mode types and most IGFETs are enhancement-mode types.

Tipe transistor séjénna
 Unijunction transistors can be used as simple pulse generators. They comprise a main body of either P-type or N-type semiconductor with ohmic contacts at éach end (terminals Base1 and Base2). A junction with the opposite semiconductor type is formed at a point along the length of the body for the third terminal (Emitter).
 Dual gate FETs have a single channel with two gates in cascode; a configuration that is optimized for high frequency amplifiers, mixers, and oscillators.
 Transistor arrays are used for general purpose applications, function generation and low-level, low-noise amplifiers. They include two or more transistors on a common substrate to ensure close paraméter matching and thermal tracking, characteristics that are especially important for long tailed pair amplifiers.
 Darlington transistors comprise a medium power BJT connected to a power BJT. This provides a high current gain equal to the product of the current gains of the two transistors. Power diodes are often connected between certain terminals depending on specific use.
 Insulated gate bipolar transistors (IGBTs) use a medium power IGFET, similarly connected to a power BJT, to give a high input impedance. Power diodes are often connected between certain terminals depending on specific use. IGBTs are particularly suitable for héavy-duty industrial applications. The Asea Brown Boveri (ABB) 5SNA2400E170100  illustrates just how far power semiconductor technology has advanced. Intended for three-phase power supplies, this device houses three NPN IGBTs in a case méasuring 38 by 140 by 190 mm and weighing 1.5 kg. éach IGBT is rated at 1,700 volts and can handle 2,400 amperes.
 Single-electron transistors (SET) consist of a gate island between two tunnelling junctions. The tunnelling current is controlled by a voltage applied to the gate through a capacitor.
 Complete list of transistor types T-Transistor.com

Bahan sémikonduktor
The first BJTs were made from germanium (Ge) and some high power types still are. Silicon (Si) types currently predominate but certain advanced microwave and high performance versions now employ the compound semiconductor material gallium arsenide (GaAs) and the semiconductor alloy silicon germanium (SiGe). Single element semiconductor material (Ge and Si) is described as elemental.

Characteristics of the most common semiconductor materials used to maké transistors are given in the table below:

The junction forward voltage is the voltage applied to the emitter-base junction of a BJT in order to maké the base conduct a specified current. The current incréases exponentialally as the junction forward voltage is incréased. The values given in the table are typical for a current of 1 mA (the same values apply to semiconductor diodes). The lower the junction forward voltage the better, as this méans that less power is required to "drive" the transistor. The junction forward voltage for a given current decréases with temperature. For a typical silicon junction the change is approximately −2.1 mV/°C.

The electron mobility and hole mobility columns show the average speed that electrons and holes diffuse through the semiconductor material with an electric field of 1 volt per méter applied across the material. In general, the higher the electron mobility the faster the transistor. The table indicates that Ge is a better material than Si in this respect. However, Ge has four major shortcomings compared to silicon and gallium arsenide: its maximum temperature is limited, it has relatively high leakage current, it cannot withstand high voltages and it is less suitable for fabricating integrated circuits. Because the electron mobility is higher than the hole mobility for all semiconductor materials, a given bipolar NPN transistor tends to be faster than an equivalent PNP transistor type. GaAs has the fastest electron mobility of the three semiconductors. It is for this réason that GaAs is used in high frequency applications. A relatively recent FET development, the high electron mobility transistor (HEMT), has a heterostructure (junction between different semiconductor materials) of aluminium gallium arsenide (AlGaAs)-gallium arsenide (GaAs) which has double the electron mobility of a GaAs-metal barrier junction. Because of their high speed and low noise, HEMTs are used in satellite receivers working at frequencies around 12 GHz.

Max. junction temperature values represent a cross section taken from various manufacturers' data sheets. This temperature should not be exceeded or the transistor may be damaged.

Al-Si junction refers to the high-speed (aluminum-silicon) semiconductor-metal barrier diode, commonly known as a Schottky diode. This is included in the table because some silicon power IGFETs have a parasitic reverse Schottky diode formed between the source and drain as part of the fabrication process.

Kemasan

Transistors come in many different packages (chip carriers) (see images). The two main categories are through-hole (or leaded), and surface-mount, also known as surface mount device (SMD). The ball grid array (BGA) is the latest surface mount package (currently only for large transistor arrays). It has solder "balls" on the underside in place of léads. Because they are smaller and have shorter interconnections, SMDs have better high frequency characteristics but lower power rating.

Transistor packages are made of glass, metal, ceramic or plastic. The package often dictates the power rating and frequency characteristics. Power transistors have large packages that can be clamped to heat sinks for enhanced cooling. Additionally, most power transistors have the collector or drain physically connected to the metal can/metal plate. At the other extreme, some surface-mount microwave transistors are as small as grains of sand.

Often a given transistor type is available in different packages. Transistor packages are mainly standardized, but the assignment of a transistor's functions to the terminals is not: different transistor types can assign different functions to the package's terminals. Even for the same transistor type the terminal assignment can vary (normally indicated by a suffix letter to the part number- i.e. BC212L and BC212K).

Panggunaan
In the éarly days of transistor circuit design, the bipolar junction transistor, or BJT, was the most commonly used transistor. Even after MOSFETs became available, the BJT remained the transistor of choice for digital and analog circuits because of their éase of manufacture and speed. However, the MOSFET has several desirable properties for digital circuits, and since major advancements in digital circuits have pushed MOSFET design to state-of-the-art. MOSFETs are now commonly used for both analog and digital functions.

Saklar
Transistors are commonly used as electronic switches, for both high power applications including switched-mode power supplies and low power applications such as logic gates.

Panguat
From mobile phones to televisions, vast numbers of products include amplifiers for sound reproduction, radio transmission, and signal processing. The first discrete transistor audio amplifiers barely supplied a few hundred milliwatts, but power and audio fidelity gradually incréased as better transistors became available and amplifier architecture evolved.

Transistors are commonly used in modérn musical instrument amplifiers, where circuits up to a few hundred watts are common and relatively chéap. Transistors have largely replaced valves in instrument amplifiers.
Some musical instrument amplifier manufacturers mix transistors and vacuum tubes in the same circuit, to utilize the inherent benefits of both devices.

Komputer
The "first generation" of electronic computers used vacuum tubes, which generated large amounts of héat and were bulky, and unreliable. The development of the transistor was key to computer miniaturization and reliability. The "second generation" of computers, through the late 1950s and 1960s féatured boards filled with individual transistors and magnetic memory cores. Subsequently, transistors, other components, and their necessary wiring were integrated into a single, mass-manufactured component: the integrated circuit. Transistors incorporated into integrated circuits have replaced most discrete transistors in modérn digital computers.

Kauntungan transistor dibandingkeun jeung solobong vakum
Before the development of transistors, vacuum tubes (or in the UK thermionic valves or just valves) were the main active components in electronic equipment. The key advantages that have allowed transistors to replace their vacuum tube predecessors in most applications are:
 Smaller size (despite continuing miniaturization of vacuum tubes)
 Highly automated manufacture
 Lower cost (in volume production)
 Lower possible operating voltages (but vacuum tubes can operate at higher voltages)
 No warm-up period (most vacuum tubes need 10 to 60 seconds to function correctly)
 Lower power dissipation (no héater power, very low saturation voltage)
 Higher reliability and gréater physical ruggedness (although vacuum tubes are electrically more rugged. Also the vacuum tube is much more resistant to nucléar electromagnetic pulses (NEMP) and electrostatic discharge (ESD))
 Much longer life (vacuum tube cathodes are eventually exhausted and the vacuum can become contaminated)
 Complementary devices available (allowing circuits with complementary-symmetry: vacuum tubes with a polarity equivalent to PNP BJTs or P type FETs are not available)
 Ability to control large currents (power transistors are available to control hundreds of amperes, vacuum tubes to control even one ampere are large and costly)
 Much less microphonic (vibration can modulate vacuum tube characteristics, though this may contribute to the sound of guitar amplifiers)

" Nature abhors a vacuum tube " Myron Glass (see John R. Pierce), Bell Telephone Laboratories, circa 1948.

Gallery
A wide range of transistors has been available since the 1960s and manufacturers continually introduce improved types. A few examples from the main families are noted below. Unless otherwise stated, all types are made from silicon semiconductor. Complementary pairs are shown as NPN/PNP or N/P channel. Links go to manufacturer datasheets, which are in PDF format. (On some datasheets the accuracy of the stated transistor category is a matter of debate.)

 2N3904/2N3906, BC182 /BC212 and BC546/BC556: Ubiquitous, BJT, general-purpose, low-power, complementary pairs. They have plastic cases and cost roughly ten cents U.S. in small quantities, making them popular with hobbyists.
 AF107: Germanium, 0.5 watt, 250 MHz PNP BJT.
 BFP183: Low power, 8 GHz microwave NPN BJT.
 LM394: "supermatch pair", with two NPN BJTs on a single substrate.
 2N2219A/2N2905A: BJT, general purpose, medium power, complementary pair. With metal cases they are rated at about one watt.
 2N3055/MJ2955: For yéars, the venerable NPN 2N3055 has been the "standard" power transistor. Its complement, the PNP MJ2955 arrived later. These 1 MHz, 15 A, 60 V, 115 W BJTs are used in audio power amplifiers, power supplies, and control.
 2SC3281/2SA1302: Made by Toshiba, these BJTs have low-distortion characteristics and are used in high-power audio amplifiers. They have been widely counterfeited  .
 BU508: NPN, 1500 V power BJT. Designed for television horizontal deflection, its high voltage capability also makes it suitable for use in ignition systems.
 MJ11012/MJ11015: 30 A, 120 V, 200 W, high power Darlington complementary pair BJTs. Used in audio amplifiers, control, and power switching.
 2N5457/2N5460: JFET (depletion mode), general purpose, low power, complementary pair.
 BSP296/BSP171: IGFET (enhancement mode), medium power, néar complementary pair. Used for logic level conversion and driving power transistors in amplifiers.
 IRF3710/IRF5210 : IGFET (enhancement mode), 40 A, 100 V, 200 W, néar complementary pair. For high-power amplifiers and power switches, especially in automobiles.

Pabrik transistor
 APT
 Fairchild Semiconductor
 Infineon Technologies
 IRF
 IXYS Corporation
 ON Semiconductor
 Panasonic Semiconductors
 Powerex
 Rohm
 Sanyo Transistors
 Semikron
 STMicroelectronics
 Toshiba Semiconductor
 Zetex Semiconductors

Tempo ogé
 Transistor avalans
 Band gap
 Bipolar junction transistor
 Compound transistor
 Transistor Darlington
 Field effect transistor
 FREDFET
 IGBT
 NPN
 PNP
 Sémikonduktor
 Transkonduktansi
 Transrésistansi
 Transistor count
 Modél transistor
 Transistor tilu lawang
 Solobong vakum
 Hukum Moore
 Very-large-scale integration

Référénsi

Patén
  — J. Bardeen et. al.
  — W. Shockley

Buku

  The invention of the transistor & the birth of the information age

Séjénna

Tumbu luar

 [http://www.audiouk.com/info/transistor.htm AudioUK's Milestones]. Photograph of first working transistor
 [http://www.pbs.org/transistor/ Transistorized]. Historical and technical information from the Public Broadcasting Service
 IEEE Virtual Museum, Let's Get Small: The Shrinking World of Microelectronics. All about the history of transistors and integrated circuits.
 [http://www.lucent.com/minds/transistor/ The Transistor Legacy Then and Now] . From Lucent Technologies (Bell Telephone Laboratories/AT&T)
 [http://www.aps.org/apsnews/1100/110004.cfm This Month in Physics History: November 17 to December 23 1947: Invention of the First Transistor]. From the American Physical Society
 [http://www.sciencefriday.com/pages/1997/Dec/hour1_121297.html 50 Years of the Transistor] . From Science Friday, December 12 1997
 [http://www.ck722museum.com/ The CK722 Museum]. Website devoted to the "classic" hobbyist germanium transistor
 [http://users.arczip.com/rmcgarra2/index.html Bob's Virtual Transistor Museum & History] . Treasure trove of transistor history
 [http://people.msoe.edu/~reyer/regency/ 1954 to 2004, the TR-1's Golden Anniversary]. In depth coverage of the Regency radio.
 The Bell Systems Memorial on Transistors.
 [http://www.ee.washington.edu/circuit_archive/parts/cross.html Jerry Russell's Transistor Cross Reference Database] .
 Pictures of TO and SOT packages
 How transistors work
 Transistor Flow Control - Scientific American Magazine (October 2005)

Transistor
Éléktronika

Transistor


The Universal Serial Bus (USB) is technology that allows a person to connect an electronic device to a computer. It is a fast serial bus type.

It is mostly used on personal computers. USB is also used on other devices, such as smartphones and video game consoles. USB connects different devices using a standard interface.

Most people use USB for computer mice, keyboards, scanners, printers, digital cameras, and USB flash drives. There are over six billion USB devices around the world.

The standard was made to improve plug and play devices. This means that a device can be plugged into a free socket, and simply work. The computer will notice the device. The computer sometimes installs special software to use the device. The device can be removed after it stops being used. This technology is called "hot swapping". "Hot swapping" means it can be plugged and unplugged while the power is on. The computer does not need to be turned off for people to change the devices.

USB can provide a small amount of power to the attached device through the USB cord. Devices that only need a little power can get it from the bus, and do not need a separate electric power plug. That allows gadgets like USB battery chargers, lights, and fans. They can also power external hard drives and SSD.

As of 2022, almost all computers have USB and have replaced older standerds. Those include the parallel port, serial port and SCSI. These old standards are rare nowadays, but very few computers in the world still use these old connectors for a few jobs where USB cannot replace them.

Brief history

The first version of the Universal Serial Bus was created in 1995. This new technology became an instant success. Since the introduction of USB, people that make electronic devices thought about how it could be used in the future. Today, USB connects a computer or other devices like laptops and MP3 players to peripheral devices.

The bus was introduced by seven companies which represent the leaders in the industry of information technology: Compaq, IBM, Intel, Microsoft, NEC, Northern Telecom, and Digital Equipment Corporation (DEC).

Several years earlier, adopters and developers of USB held a meeting called Plugfest at a special hotel in California to test their devices. They selected a hotel that included rooms for sleeping and for testing. The meeting lasted three days. During the meeting, the representatives of about 50 companies connected their USB devices to one general host system.

The logo of the USB device also has its own history. The USB logo was in development for several months.

 1994 - Seven companies united to begin the development of USB.
 1995 - 340 companies formed the USB Implementation Forum.
 1996 - More than five hundred USB products were already developing around the world.
 1997 - USB Implementation Forum became richer with 60 more companies.
 1998 - USB becomes the most popular technology on the market of electronics.
 2000 - The introduction of USB 2.0. Today it represents the most widely used USB device.
 2005 - USB becomes wireless.
 2008 - USB 3.0 is introduced. It is over 10 times faster than USB 2.0.
 2013 - USB 3.1 is introduced. It is about twice as fast as USB 3.0.
 2015 - USB Type-C is introduced. It is a reversible connector, which means that you can plug it in both ways.
 2019 - USB 4 is introduced. It is over 8 times faster than USB 3.0.

Different standards
Currently, five different USB standards are used: USB 1.0, USB 1.1, USB 2.0, USB 3.0 and USB 3.1. USB 3.1 was released in 2016 and doubled the speed of 3.0. It optionally uses a different connector called USB Type-C, which is reversible (meaning you can plug it in both ways). USB 1.0 is now rarely used.

USB offers five different transfer speeds: 1.5 MBit per second (called low speed), 12 MBit per second (Full Speed), 480 MBit/second (Hi Speed), 5Gbit per second (called super speed),  and 10 Gbit/s ("super speed+"). Hi speed is only available in USB 2.0 and later, and Super speed is only available in USB 3.0. These speeds are raw bit rates (in Million bits per second). The actual data rate is usually lower due to protocol overhead.

In order to use the hi speed transfer rate, the USB controller and the connected device both need to support it. USB is backwards compatible. Faster and slower USB devices and controllers can be connected together, but they will run at the slower speed.

USB Hubs

As of 2022, almost all computers sold today have USB ports, and most of them support USB 3.0 or later and have at least one USB-C port. Apple Macbooks only have USB-C ports. The number of ports they have is usually limited, though. Between two and four ports are common. USB allows connecting USB hubs to add more USB ports.

The hubs themselves are also compliant to one of the USB standards. Devices connected to a USB 2.0 hub will only go as fast as USB 2.0 rates. Devices connected to a later controller can use different standards.

USB Connectors

USB was designed to be easy to use. The engineers learned from other connectors before they designed USB connectors. There are 3 connectors.
 Type A, commonly used at computer end of cable
 Micro-A (rare)
 Type B, at peripheral end, rare except for printers
 Micro-B, at peripheral end, for most smartphones
 Type C, at either end. As of 2022, many computers, phones and peripherals use it.

Usability
 It's not possible to plug in a USB A or B connector the wrong way. They can not go in upside down, and it is obvious from the look and kinesthetic feeling, when it goes in properly. Sometimes, however, a user doesn't understand or see how the connector goes, so it might be necessary to try both ways.
 Type C USB connectors can be plugged in both ways. It does not matter which way the connector is plugged in.
 There is no need to push or pull very hard to plug or unplug it. This was in the specification. USB cables and small USB devices are held in place by the gripping force from the receptacle. USB does not need screws, clips, or other fasteners. The force needed to make or break a connection is small. This allows connections to be made in awkward positions or by those with motor disabilities.
 Before the advent of Type C, the connectors enforced the directed topology of a USB network. USB does not support cyclical networks, so the connectors from incompatible USB devices are themselves incompatible. Unlike other communications systems (e.g. RJ-45 cabling) gender-changers were almost never used before the advent of USB-On-The-Go (OTG), making it difficult to create a cyclic USB network.

Durability
 The connectors are designed to be tough. Early connector designs were fragile, with pins or other delicate components which could easily bend or break, even if treated gently. The electrical contacts in a USB connector are protected by a plastic tongue. The entire connecting assembly is usually further protected by an enclosing metal sheath. As a result, USB connectors can safely be handled, inserted, and removed, even by a small child.
 The connector construction always ensures that the external sheath on the plug contacts with its counterpart in the receptacle before the four connectors within are connected. This sheath is typically connected to the system ground, allowing otherwise damaging static charges to be safely discharged by this route (rather than via delicate electronic components). This means of enclosure also means that there is a (moderate) degree of protection from electromagnetic interference afforded to the USB signal while it travels through the mated connector pair (this is the only location when the otherwise twisted data pair must travel a distance in parallel). As well, the power and common connections are made after the system ground but before the data connections. This type of staged make-break timing allows for safe hot-swapping and has been used for connectors in the aerospace industry.
 The newer USB micro receptacles are designed to allow up to 10,000 cycles of insertion and exertion between the receptacle and plug, compared to 500 for the standard USB and Mini-USB receptacle. This is done by adding a locking device and by moving the leaf-spring connector from the jack to the plug, so that the most-stressed part is on the cable side of the connection. This change was made so that the connector on the (relatively inexpensive) cable would bear the most wear instead of the micro-USB device.

Compatibility
 The USB standard specifies relatively big tolerances for compliant USB connectors. This is done to minimize incompatibilities in connectors produced by different vendors (a goal that has been very successfully achieved). Unlike most other connector standards, the USB specification also defines limits to the size of a connecting device in the area around its plug. This was done to prevent a device from blocking adjacent ports due to its size. Compliant devices must either fit within the size restrictions or support a compliant extension cable which does.
 Two-way communication is also possible. Usually cables have only plugs, and hosts and devices have only receptacles: hosts having type-A receptacles and devices type-B. Type-A plugs only join with type-A receptacles, and type-B with type-B. However, an extension to USB called USB On-The-Go allows a single port to act as either a host or a device — chosen by which end of the cable plugs into the socket on the unit. Even after the cable is hooked up and the units are talking, the two units may "swap" ends under program control. This facility targets units such as PDAs where the USB link might connect to a PC's host port as a device in one instance, yet connect as a host itself to a keyboard and mouse device in another instance.

How USB works
A USB system has an asymmetric design. It is made of a host, several downstream USB ports, and multiple peripheral devices connected in a star topology. Additional USB hubs may be included in the tiers, allowing branching into a tree structure with up to five tier levels.

A USB host can have multiple host controllers. Each host controller provides one or more USB ports. Up to 127 devices, including the hub devices, may be connected to a single host controller.

USB devices are linked in series through hubs. There is always one hub known as the root hub. The root hub is built into the host controller. There are special hubs, called "sharing hubs". These allow multiple computers to access the same peripheral devices. They work by switching the access between PCs, either manually or automatically. They are popular in small-office environments. In network terms, they converge rather than diverge branches.

A physical USB device can have several logical sub-devices that are referred to as device functions. A single device may provide several functions, for example, a webcam (video device function) with a built-in microphone (audio device function).

USB device communication is based on pipes (logical channels). Pipes are connections from the host controller to a logical entity on the device named an endpoint. The term endpoint is occasionally used to incorrectly refer to the pipe. A USB device can have up to 32 active pipes, 16 into the host controller and 16 out of the controller.

Each endpoint can transfer data in one direction only, either into or out of the device, so each pipe is uni-directional. Endpoints are grouped into interfaces and each interface is associated with a single device function. An exception to this is endpoint zero, which is used for device configuration and which is not associated with any interface.

When a USB device is first connected to a USB host, the USB device enumeration process is started. The enumeration starts by sending a reset signal to the USB device. The speed of the USB device is determined during the reset signaling. After reset, the USB device's information is read by the host, then the device is assigned a unique 7-bit address. If the device is supported by the host, the device drivers needed for communicating with the device are loaded and the device is set to a configured state. If the USB host is restarted, the enumeration process is repeated for all connected devices.

The host controller polls the bus for traffic, usually in a round-robin fashion, so no USB device can transfer any data on the bus without an explicit request from the host controller.

Host controllers
The computer hardware that contains the host controller and the root hub has an interface for the programmer. It is called Host Controller Device (HCD) and is defined by the hardware implementer.

For USB 1.0 and 1.1, there were two different HCD implementations, Open Host Controller Interface (OHCI) and Universal Host Controller Interface (UHCI). OHCI was developed by Compaq, Microsoft and National Semiconductor, UHCI by Intel.

VIA Technologies licensed the UHCI standard from Intel; all other chipset implementers use OHCI. UHCI relies more on software. This means UHCI is slightly more processor-intensive than OHCI but easier and cheaper to make. Because there were two different implementations, operating system vendors and hardware vendors  needed to develop and test on both of them. This increased cost.

The USB specification does not specify any HCD interfaces and is not concerned with them. In other words, USB defines the format of data transfer through the port, but not the system by which the USB hardware communicates with the computer it sits in.

During the design phase of USB 2.0, the USB-IF insisted  that there was only one implementation. The USB 2.0 HCD implementation is called the Enhanced Host Controller Interface (EHCI). Only EHCI can support hi-speed (480 Mbit/s) transfers. Most of PCI-based EHCI controllers have other HCD implementations called 'companion host controller' to support Full Speed (12 Mbit/s) and may be used for any device that claims to be a member of a certain class. An operating system is supposed to implement all device classes, so it can provide generic drivers for any USB device. Device classes are decided upon by the Device Working Group of the USB Implementers Forum.

USB device classes
Device classes include:

 Use class information in the Interface Descriptors. This base class is defined to be used in Device Descriptors to indicate that class information should be determined from the Interface Descriptors in the device.

Related pages
 FireWire

References

Computer hardware
Computer buses
USB

USB


The Vijayanagara empire was an Indian empire. From 1336 and afterwards, it was in the Deccan, in the peninsula and in southern India. It was founded by Harihara (Hakka) and his brother Bukka Raya.  The empire is named after its capital city Vijayanagara, now Hampi in modern Karnataka, India.  It began in 1336 and ended in 1660, though in its last century it began losing its power. Stories of the empire's creation and history are not certain, though tales of the empire's wealth and power were described by European travellers such as the Portuguese travelers Domingo Paes and Nuniz, and the Venetian traveler Niccolò Da Conti.

Dynasties and kings
This list is based on the book by Robert Sewell (A Forgotten Empire).

Sangama Dynasty
Harihara I (Deva Raya) 	1336-1343/56(some accounts claim that there was brief period of other ruler probably a 3rd brother)
Bukka I	1343/56-1379
Harihara II	1379-1399
Bukka II	1399-1406
Deva Raya I	1406-1412
Vira Vijaya	1412-1419
Deva Raya II	1419-1444
(unknown)	1444-1449
Mallikarjuna	1452-1465	(Dates uncertain)
Rajasekhara	1468-1469	(Dates uncertain)
Virupaksha I	1470-1471	(Dates uncertain)
Praudha Deva Raya	1476-?	(Dates uncertain)
Rajasekhara	1479-1480	(Dates uncertain)
Virupaksha II	1483-1484	(Dates uncertain)
Rajasekhara	1486-1487	(Dates uncertain)

Saluva Dynasty
Narasimha	1490-?
Narasa (Vira Narasimha)	?-1509
Krishna Deva 	1509-1529
Achyuta	1529-1542
Sadasiva (puppet ruler in the hands of Ram Raya)	1542-1567

Tuluva dynasty
Rama (ruled in practice)	1542-1565
Tirumala (ruled in practice)	1565-1567
Tirumala (crowned ruler)	1567-1575
Ranga II	1575-1586
Venkata I	1586-1614

Aravidu (dates are not known), includes these rulers. There is certainly more than one ruler under each name.
Ranga
Venkata
Rama

Other websites
 History of Karnataka - Mr. Arthikaje
 Indian Inscriptions - Archeological Survery Of India
 A Forgotten Empire: Vijayanagar: A Contribution to the History of India
 http://freeindia.org/biographies/greatlkings/hakkabukka/index.htm(Biography of Hakka and Bukka.)
 Vijayanagar Empire, Dr. Jyotsna Kamat
 Hampi - History and Tourism

History of India
Former empires
1336 establishments
1660 disestablishments
14th-century establishments in India
Disestablishments in India
Former countries in South Asia

Vijayanagara Empire


Nigeria's present national anthem, "Arise, O compatriots" was adopted in 1978.

Arise, O compatriots, Nigeria's call obey
To serve our fatherland
With love and strength and faith
The labour of our heroes past
Shall never be in vain
To serve with heart and might
One nation bound in freedom, peace and
unity.

Oh God of creation, direct our noble cause
Guide our leaders right
Help our youth the truth to know
In love and honesty to grow
And living just and true
Great lofty heights attain
To build a nation where peace and justice
shall reign

It replaced the anthem "Nigeria We Hail Thee", adopted on independence in 1960. The words were written by a British expatriate, Lilian Jean Williams, while the music was composed by Frances Benda.

Nigeria, we hail thee,
Our own dear native land,
Though tribe and tongue may differ,
In brotherhood we stand,
Nigerians all, and proud to serve
our sovereign motherland.

Our flag shall be a symbol,
That truth and justice reign,
In peace or battle honoured,
And this we count as gain
To hand on to our children
A banner without stain

O Lord of all creation,
Grant this our one request
Help us to build a nation
Where no man is oppressed
And so, with peace and plenty,
Nigeria may be blessed.

Itokasi

Àwọn àmì-ìdámọ̀ oníbínibí ilẹ̀ Nàìjíríà

Dìde, Èyin Ará


Dina matematika, probability density function dipaké keur ngagambarkeun probability distribution di watesan integrals. Lamun probability distribution mibanda densiti f(x), saterusna interval tak terhingga [x, x + dx] mibanda probabiliti f(x) dx. Probability density function bisa ogé ditempo tina versi "smoothed out" histogram: if one empirically méasures values of a variabel acak repéatedly and produces a histogram depicting relative frequencies of output ranges, then this histogram will resemble the random variable's probability density (assuming that the variable is sampled sufficiently often and the output ranges are sufficiently narrow).

Formally, a probability distribution has density f(x) if f(x) is a non-negative Lebesgue-integrable function R → R such that the probability of the interval [a, b] is given by

for any two numbers a and b. This implies that the total integral of f must be 1. Conversely, any non-negative Lebesgue-integrable function with total integral 1 is the probability density of a suitably defined probability distribution.

Contona, sebaran seragam dina interval [0,1] mibanda probabiliti densiti f(x) = 1 keur 0 ≤ x ≤ 1 jeung nol dimamana. Standar sebaran normal mibanda probabiliti densiti

.

Lamun variabel acak X dibérékeun sarta distribusina kaasup kana fungsi probabiliti densiti f(x), mangka nilai ekspektasi X (lamun éta aya) bisa diitung ku

Not every probability distribution has a density function: the distributions of discrete random variables do not; nor does the Cantor distribution, even though it has no discrete component, i.e., does not assign positive probability to any individual point.

A distribution has a density function if and only if its cumulative distribution function F(x) is absolutely continuous. In this case, F is almost everywhere differentiable, and its derivative can be used as probability density. If a probability distribution admits a density, then the probability of every one-point set {a} is zero.

It is a common mistake to think of f(a) as the probability of {a}, but this is incorrect; in fact, f(a) will often be bigger than 1 - consider a random variable with a uniform distribution between 0 and 1/2.

Dua densiti f jeung g for the same distribution can only differ on a set of Lebesgue measure zero.

Tempo oge:
 likelihood
 probability mass function
 exponential family

Rujukan
 Wikipédia basa Inggris, disalin ping 17 Agustus 2004.

Fungsi dénsitas probabilitas


ACM, singkatan dari Association for Computing Machinery (Asosiasi untuk Permesinan Komputer), adalah sebuah serikat ilmiah dan pendidikan komputer pertama di dunia yang didirikan pada tahun 1947. Anggota ACM sekitar 78.000 terdiri dari para profesional dan para pelajar yang tertarik akan komputer. Dia bermarkas besari di Kota New York.

Aktivitas

ACM diatur menjadi 170 bagian("chapter") lokal dan 34 grup minat khusus (special interest group, SIG), di mana mereka melakukan kebanyakan kegiatan mereka.

Banyak dari SIG, seperti SIGGRAPH, SIGPLAN dan SIGCOMM, mensponsori konferensi teratur yang menjadi terkenal sebagai acara utama untuk memperkenalkan inovasi baru dalam bidang tertentu. SIG juga menerbitkan sejumlah jurnal khusus, majalah, dan surat berita.

ACM juga mensponsori acara yang berhubungan dengan ilmu komputer seperti
ACM International Collegiate Programming Contest (ICPC) yang mendunia, dan telah mensponsori beberapa acara lainnya, seperti pertandingan catur antara Garry Kasparov dan komputer IBM Deep Blue.

Journal of the ACM, and general magazines for computer professionals, Communications of the ACM and Queue. Many of the great debates in the history of computing have taken place in the pages of Communications. Examples include the famous "GOTO considered harmful" letter, the issue of what to call the then-fledgling field of computer science, and the issue of changing ACM's name (since the "machinery" in question is no longer the size of a house and is now measured in micrometres). All three attempts at changing ACM's name have failed.

ACM has made almost all of its publications available online at its Digital Library and also has a Guide to Computing Literature. It also offers insurance and other services to its members.

Digital Library

ACM has created a digital library where it has made all of its publications available. ACM's digital library is the world's largest collection of information on computing machinery and contains an archive of journals, magazines, conference proceedings online, and the recent issues of ACM's publications. Online services include a forum called Ubiquity and Tech News digest, both containing the latest information about the IT world.

Competition

ACM's primary competitor is the IEEE Computer Society. It is difficult to generalize accurately about the distinction between the two, but ACM focuses on theoretical computer science and end-user applications while IEEE focuses more on hardware and standardization issues. Another blunt way to state the difference is that ACM is for computer scientists and IEEE is for electrical engineers, although the largest IEEE subgroup is its Computer Society. Of course, there is significant overlap between the two organizations, and they occasionally cooperate on projects like developing computer science curricula.

Leadership

The President of the ACM for 2004–2006 is David A. Patterson of the University of California, Berkeley, Amerika Serikat.

Infrastructure

ACM has four "Boards" that make up various committees and subgroups, to help Headquarters staff maintain quality services and products. These boards are as follows:

 Publications
 SIG Governing Board
 Education
 Membership Services Board

ACM's Committee on Women in Computing

ACM's committee on women in computing is set up to support, inform, celebrate, and work with women in computing. Dr. Anita Borg was a great supporter of ACM-W. ACM-W provides various resources for women in computing as well as high school girls interested in the field. ACM-W also reaches out internationally to those women who are involved and interested in computing.
-->

Lihat pula

 Garis waktu penghitungan 750 BC-1949
 Skema pengklasifikasian ACM
 Penghargaan Grace Murray Hopper, diberikan oleh ACM
 Penghargaan Turing
 Kecerdasan Buatan

Pranala luar

 ACM official website
 ACM portal for publications

ACM
Organisasi internasional
Asosiasi profesional
Organisasi berhubungan dengan komputer

Association for Computing Machinery


A stimulant is any of a group of drugs that can increase alertness and awareness, usually for a short time only. Most stimulants have more side-effects than other drugs. Some are classified as illegal drugs, most can cause addiction. For this reason, most legal stimulants are only available on prescription. Stimulants act on the nerves: Stimulants cause more neurotransmitters to the synapse (this is the gap between different nerves)

Most stimulants fall into one of the following groups:
 Amphetamine and its derivates: Methylphenidate, Methamphetamine, Pseudoephedrine Ephedrine, Ecstasy
 Xanthines: Caffeine, Theophylline, Theobromine
 Piperazine and its derivates: Benzylpiperazine, Trifluoromethylphenylpiperazine
 Various others: Cocaine, Nicotine, Modafinil

Some of the substances mentioned above can be used to treat certain diseases. Some are mostly used as illegal drugs.

Psychoactive drugs

Stimulant


Espionage or spying is a practice of getting information about an organization, society, or country that is meant to be secret or confidential, without permission. Espionage usually involves having access to where the needed information is stored or to the people that know the information. In wartime, espionage is a war crime. The person who does it is called a "spy" or more vaguely an "agent". A double agent is one who trades information to both sides, and is (without their knowledge) being employed by both sides.

Espionage


An optical drive is usually a CD drive or DVD drive. Optical means it uses lenses. The drive uses a light called a laser. A laser is the most exact and powerful sort of light but the laser in the drive is very, very small. The CD or DVD disk is similar to a mirror and the laser light reflects off it. The disk has very small (microscopic) codes written on it. The drive has a very small camera lens beside the laser which can read the codes. Another part of the drive is plugged in to the computer by a wire (inside) and the code goes through the wire as a signal to the computer.

List of optical drives
CD drive
DVD drive
Blu-ray Disc drive
HD-DVD drive
LaserDisc drive

Computer science
Machines
Electronics

Optical disc drive


Lancashire is a ceremonial county in the North West of England. Its two cities are Lancaster and Preston. Before 1974, Liverpool and Manchester were part of the administrative county of Lancashire.

Rivalry
The county has developed a fierce rivalry with Yorkshire, the next county east. This comes from rivalry in sport, such as in cricket, and comes from the War of the Roses.

Places
A big attraction in Lancashire is Blackpool, an English seaside resort, which has a theme park called Blackpool Pleasure Beach. It has the second largest rollercoaster in Europe ("The Big One") and Blackpool Tower, a tower which was made to look like the Eiffel Tower in Paris.

Lancashire has market towns (like Chorley) and small villages (like Bretherton, Croston and Eccleston). It is just south of an area of outstanding natural beauty called the Lake District. Lancashire also has a lot of pleasant countryside such as White Coppice and the Rivington Moors.

Food
A famous food from Lancashire is "Lancashire hotpot" which is made of meat, onion or other vegetables and potatoes. It is often found on many pub menus in the county and in other places in Britain.

People
The people of Lancashire are known for their friendly nature. Humour is also an important part of Lancashire life.

Ceremonial counties of England

Lancashire