The History of Computer hardware
Major developments in hardware have taken place over the past 60 years. To make these developments more clear, computes are often categorized into “generations” to mark technological breakthroughs. Beginning in the 1940s, first generation computers used vacuum tube technology. They were bulky and unreliable, generated excessive heat, and where difficult to program. Second-generation computers operated on integrated circuits, which enabled computers to be even smaller, faster, more reliable, and more sophisticated.
Remote data entry and telecommunication were introduced during this generation. Fourth-generation computers continued several trends that further improved speed and ease of use: miniaturization, very large scale integration (VLSI) circuits, widespread use of personal computers, and optical discs (disc written or encoded and read using laser optical device). The current fifth-generation computers include parallel processing (computer containing hundreds or thousands of CPUs for rapid data processing), gallium arsenide chips that run at higher speeds and consume less power than silicon chips, and optical technologies.
Because silicone can’t emit light and has speed limitations, commuter designers have concentrated on technology using gallium arsenide, in which electrons move almost five times faster than silicon. Devices made with this synthetic compound can emit light, withstand higher temperatures, and survive much higher dose of radiation than silicon devices. The major problems with gallium arsenide are difficulties in mass production.
This material is softer and more fragile than silicon, so it breaks more easily during slicing and polishing. Because of high costs and difficulty of production, the USA military is currently the major user of this technology. However, research continues to eliminate some shortcomings of this technology.
The field of optical technologies involves the application and properties of light, including its interactions with laser, fibre optics, telescopes, and so forth. These technologies offer faster processing speed, parallelism (seven thousand light beams can pass through an ordinary device), AND interconnection-much denser arrays of interconnection are possible because light rays don’t affect each other.
Optical computing is in its infancy, and more research is needed to produce a full-featured optical computer. Nevertheless, storage devices using this technology are revolutionizing the computer field by enabling massive amounts of data to be stored in very small spaces.
Classes of Computers
usually, computers are classified based on cost, amount of memory, speed and sophistication. using these criteria, computers, minicomputers, mainframes, or supercomputers. Super computers are the most powerful; they also have the highest storage capabilities and the highest price.
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The Power of Computers
Computers draw their power form three factors that far exceed human capacities: speed, accuracy and storage.
Speed
Computers process data with amazing speed. They are capable of responding to request faster that humans can, which improves efficiency. Today’s high-speed computers make it possible for knowledge workers to perform tasks much faster than with slower computers of the past. Typically, computer speed is measured as the number of instructions performed during the following fractions of a second:
- Millisecond: 1/1,000 of a second
- Microseconds: 1/1,000,000 of a second
- Nanosecond: 1/1,000,000,000 of a second
- Picosecond: 1/1,000,000,000,000 of a second
Accuracy
Unlike humans, computers don’t make mistakes. To understand computer accuracy more clearly, take a look at these two numbers:
4.0000000000000000000000001
4.0000000000000000000000002
To humans, these two numbers are so close that they are usually considered equal. To a computer, however, these two numbers are completely different. This degree of accuracy is critical in many computer applications. On a space mission, for example, computers are essential for calculating reentry times and locations for space shuttles. A small degree of inaccuracy could lead the space shuttle to land in Canada instead of the United States.
Storage and Retrieval
Storage means saving data in computer memory, and retrieval is accessing data from memory. Computers can store vast quantities of data and locate a specific item quickly, which makes knowledge workers more efficient in performing their jobs.
In computers, data is stored in bits. A bit is a single value of 0 or 1, and 8 bits equal 1 byte. A byte is the size of a character. For example, the word computer consists of 8 characters or 8 bytes (64 bits).
Every character, number, or symbol on the keyboard is represented as a binary number in computer memory. Binary system consists of 0s and 1s, with a 1 representing “on” and a 0 representing “off”, similar to a light switch. Computers and communication systems use data codes to represent and transfer data between computers and network systems. The most common data code for text files, PC applications, and the Internet is American Standard Code for Information Interchange (ASCII), developed by the American National Standards Institute. In an ASCII file, each alphabetic, numeric, or special character is represented with a 7-bit binary number (a string of 0s or 1s). Up to 128 characters can be defined. There are two additional data codes used by many operating systems: Unicode and Extended ASCII. Unicode is capable of representing 256 characters, and Extended ASCII is an 8-bit code that also allows representing 256 characters.
Before the ASCII format, IBM’s Extended Binary Coded Decimal Interchange Code (EBCDIC) was popular. In an EBCDIC file, each alphabetic, numeric, or special character is represented with an 8-bit binary number.
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