# Introduction to Computers/Processor

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## Logic gates (on and off makes computers work)
### Vacuum tube

A vacuum tube is a small glass tube the size of a light-bulb. It was invented in 1907. It was meant to amplify and act like a switch. It facilitated the flow of electrons. The vacuum tube was replaced in computers by the transistor in 1948.
Because a vacuum must be provided in the form of an evacuated enclosure in which the electrons can move without collisions with gas molecules, these devices were originally called vacuum tubes or electron tubes in the US, and thermionic valves in Britain.

### Transistor

A transistor is an electrically operated logic gate or switch that alternates between "on" and "off" millions of times per second. May be used in many different digital and analog functions due to its fast response and accuracy. Transistors are made of semiconductor material. Most transistors are made of silicon, and some from germaniumGermanium is a chemical element with the symbol Ge and atomic number 32. It is a lustrous, hard-brittle, grayish-white metalloid in the carbon group, chemically similar to its group neighbors silicon and tin. Source Article. There are usually at least three terminals that connect to an electronic circuit. This allows electron flow when turned "on", but not allowing it when it is turned off. Only an electrically charged center will allow electrons to flow. Transistors are used to amplify or switch electronic signals.
Transistor

### Integrated circuit

An integrated circuit is a mini electronic circuit which consists of multiple transistors. More transistors close together increased capability and consumed little power. Integrated circuitsAn integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. were invented in 1958.
Integrated circuits contain solid state technology, which is usually silicon. This is due to the technological advancements of integrated circuits which are now created in a single step. The main advantages of integrated circuits were their cost and performance.

### Microprocessor

8085 microprocessor is an 8-bit microprocessor with a 40 pin dual in line package. The address and data bus are multiplexed in this processor which helps in providing more control signals. 8085 microprocessor has 1 Non-maskable interrupt and 3 maskable interrupts. It provides serial interfacing with serial input data (SID) and serial output data (SOD).

## Binary

Binary numeral system is using two symbols, usually "0" and "1". A binary number can be represented by bits. Binary refers to the system of information transfer through the processor. The binary code occurs in digits of 0 and 1. The processor understands these codes as off and on respectively.
Binary system has two digits 0 and 1. In the computer 0 represented by the electrical current off and 1 by current being on.

### Bit - b

A bit is short for binary digit. Each bit can be a 0 or a 1. A computer understands 0's as an electrical circuit that is turned off and 1's as an electrical circuit that is turned on. All information and programs on a computer are represented by these bits.
A bit is the smallest representative value of data.
In the binary system 0 or 1 is called a bit.
The bit is also a unit of measurement, the information capacity of one binary digit. It has the symbol bit, and less formally "b". The unit is also known as the Shannon, with symbol "Sh".
The first known binary numbers were introduced by an Indian mathematician Pingala and it was written in Hindu numbers.

### Byte - B

A byte is 8 bits, a number between 0 and 255 (2$^8$=256). It is symbolized by a capital B.
These bits are combined in groups to represent numbers, letters, or special characters. Bytes are also used to represent the capacity of the computer's memory, whether in KB or MB. In system programming languages, the byte is one of the basic integral data types.

### Kilobyte - kB

Otherwise known as K, KB, Kbyte and kB. A kilobyte is used as computer storage that is equal to 1000 bytes.
In reality a kilobyte equals 1024 bytes. 2$^{10}$ = 1024 bytes.
In older computers, this was a much more common unit of measurement for memory than it is currently.

### Megabyte - MB

1MB = 1024 KB
1 MB equals about 500 pages of text.
A KB consists of 1024 bytes , a MB of 1024 KB (GB of 1024 MB, TB of 1024 GB).

### Gigabyte - GB

The most common size for RAM nowadays (in 2009) is 1 GB (1024 MB) sticks which is in the main stream pricing range.

### Terabyte - TB

1 TB = 1024 GB
Mostly used size in large databases of banking and telecommunication applications, and as of the year 2010 it is now standard in top tier computers.

## Codes
### Extended Binary Coded Decimal Interchange Code - EBCDIC

Extended Binary Coded Decimal Interchange Code (EBCDIC): a binary code used with large computers, such as mainframes. This code uses 8 bits (0's or 1's) for each character and was developed by IBM in 1963 and 1964.
EBCDIC code pages and ASCII-based code pages are incompatible with each other.
It was designed by IBM to extend the Binary-coded decimal. EBCDIC

### American Standard Code for Information Interchange - ASCII

Pronounced: "ask-ee". A type of binary code that uses 1 byte (8 bits) for each character. A total of 256 characters. ASCII is the most common code used in microcomputers. ASCII stands for American Standard Code for Information Interchange
It is a "numerical representation of a character" and can be viewed in a table format (view at link)
Text-only files containing no graphics and no formatting such as boldface and italic. ASCII format is used to transfer documents between computers, such as PC and Macintosh. Such files may use the .txt (for text) extension.

### Unicode

Unicode is a type of binary coding which uses an exclusive number for every character. It uses up to 4 bytes (currently 21 bits) for each of these characters, instead of the 1 byte per character of EBCDIC. Unicode can handle 2,097,152 (2$^{21}$) character combinations (instead of the 256 characters of ASCII) which means most of the world's written languages can be represented by a single character set.
In text processing, Unicode takes the role of providing a unique code point — a number, not a glyph — for each character. In other words, Unicode represents a character in an abstract way and leaves the visual rendering (size, shape, font or style) to other software, such as a web browser or word processor.

## CPU (the brains and its helpers)
### Control unit

As a component of a CPU (Central Processing Unit), the control unit is sometimes known as the "brain within the brain." This is because the control unit regulates the flow of information within a processor. It also manages all the endeavors other units participate in within it. This can be summed up in the saying, "it controls what happens inside the processor, which in turn controls the rest of the PC." The control unit directs electronic signals as well.
The main operation of most CPU's is to complete a sequence of instructions, which are stored, called programs. The programs are represented by a series of numbers that are kept in a computers memory. There are four steps in the operation: fetch, decode, execute and writeback. (Using Information Technology: A practical Introduction to Computers & Communications, p. 208)

### ALU

ALU represents Arithmetic Logic Unit
* It is a digital circuit that does arithmetic operations such as addition, subtraction, multiplication and division.
* The ALU is a big part of the central processing unit(CPU).
* It also does logical operations such as comparing two pieces of data to see whether one is equal, greater than, or less than (=,>,<).
* It is the fundamental piece for the CPU, even simple processors have ALU's.
In 1945 John von Neumann wrote a report with the ALU concept in it.

### Construction

The die size refers to the physical size of the processor. Manufactures are racing to miniturize consumer electronics to reduce the cost, power consumption and increase CPU efficiency. The 32 nm processor is the next evolution after the 45 nm Pyren Intel CPU.
Toshiba and NEC Electronics will work together on advanced chip manufacturing technologies to help them continue the steady miniaturization of consumer electronics products.
Due to the increasing cost of manufacturing such processing chips, many companies have made joint venture to share the costs of manufacturing. Toshiba and NEC Electronics may make the 32 nm processor a complete joint venture down to the manufacturing.

## Speed
### Multicore

Multicore is a processor which has two or more processors combined onto one piece of silicon. This helps to enhance speed and performance by dividing the work between each processor.
An advantage of having two or more cores is that a computer can perform several tasks simultaneously, rather than having tasks queued in line, however, they will still freeze up under tense or error operation.

### Gigahertz

Although not necessarily dealing with computers, it here refers to how many times a set of bits (words) are presented to the processor in a second. The processor receives information in waves. Each of the 32 (or 64 according to the word size) receptacles receive either a zero or a one (electric charge or no charge) in one cycle. Then the next cycle comes with its own set of bits. The rate at which these waves enter into the processor is measured in cycles per second (Hertz or Hz). Computers are so fast these days that it is measured in billions (Giga) of cycles per second (GHz).
Hertz is named after the German physicist Heinrich Rudolf HertzHeinrich Rudolf Hertz (22 February 1857 – 1 January 1894) was a German physicist who first conclusively proved the existence of the electromagnetic waves predicted by James Clerk Maxwell's equations of electromagnetism. .

### Word size

Word size is the numbers of bits processed by the processor in one cycle. Modern PC's had processors with word sizes of 16 bits, then they increased to 32 bits (pentium 2$^5$=32), and now 64 bits. When the PC processor has more bits it can transfer the data within each microprocessor quicker than that with a lower amount of bits.

### Cache

If the processor is a doctor, and RAM is the big waiting room with everyone in it, cache is like the examining room that you still have to wait in before the doctor arrives.
Cache briefly stores data which the Processor will use soon. This is done so that while working the computer does not have to consistently search through the motherboard, speeding the process up. There are three types of caches. They include level 1, level 2 and level 3.
The first level cache is called the internal cache which is part of the microprocessor chip and contains the least kilobytes of the three, which operates faster even though it has lower capacity. It was the first developed (thus the number), but didn't satisfy our need for the volume of data that we needed to process quickly. So Level 2 cache was developed. It is external cache (separate from the microprocessor), but has more memory (from 64 kB to 2MB). The level 3 cache is also separate from the microprocessor but only in high end computers. The processor which has a higher cache are faster & also costlier.

## Future
### Moore’s law

In 1965, Gordon E. Moore observed that the number of transistors placed on an affordable integrated circuit were increasing exponentially, doubling approximately every two years. The capability to measure digital electronic devices (such as memory capacity and processing speed) is directly linked to Moore's law. He predicted this rate would continue; the rate was sustained until about 2012 when it began to slow somewhat.
Moore's law is an important part of computer history. The most popular formulation is of the doubling of the number of transistors on integrated circuits every two years. At the end of the 1970s, Moore's Law became known as the limit for the number of transistors on the most complex chips
It includes things other than just the number of transistors, but also processing speed, memory size, and image resolution in digital cameras.

### Optical

Optical circuits are circuits using 'light' not electricity.
Optical circuit is one or more circuits made of solid state components. Usually made on a semiconductor or dielectric substrate. It is made up of light sources, optical filters, and photodetectors. It allows a circuit to interact with another while remaining electrically separated from the other.
Simply any optical component within the computer uses light instead of electricity.

### Nano

Nanotechnology is described as a field of applied science and technology whose unifying theme is the control of matter on the atomic and molecular scale; normally 1 to 100 nanometers, and the fabrication of devices with critical dimensions that lie within that size range.
One nanometer (nm) is one billionth, or 10$^{-9}$ of a meter. Nanometer to a meter is the same as that of a marble to the size of the earth.

### SETI

We can detect complex radio signals from outer space, but most or all are believed to be created naturally from quasars for example.
SETI (search for extra terrestrial intelligence) is a non profit organization that uses modern computer technology to look for intelligent patterns within the radio signals. It is a search for other lifeforms in our universe.
You can contribute by joining the team and allowing your computer to process data while you're not using it. The data is then returned to the server for further analysis. It is also a favorite tool for "FOLDERS" to contribute their processing power.