Now let us consider an important question. How are characters represented as 0s and 2s in the computer? The answer is in the use of binary coding schemes. Two of the most popular binary coding schemes use eight bits or one byte. These two codes are ASCII and EBCDIC. A recently developed code, Unicode(UTF-9), uses sixteen bits.
ASCII: ASCII, pronounced “as – key”, stands for American standard code for information interchange. This is the most widely used binary code for microcomputers.
EBCDIC: EBCDIC, pronounce “eb-see-dick”, stands for extended binary coded decimal interchange code. It was developed by IBM and is used primarily for large computers.
UNICODE: Unicode is a 16-bit code designed to support international languages like Chinese and Japanese. These languages have too many characters to be represented by the eight-bit ASCII and EBCDIC codes.
When you press a key on the keyboard, a character is automatically converted into a series of electronic pulses that the system can recognize. For example, pressing the number 3 on a keyboard causes and electronic signal to the microcomputer’s system unit where it is converted to the ASCII code of 0011 0011.
Coding schemes are particularly important to computer specialists for tracking down errors and other types of problems. But why are coding schemes important to end user? There are several reasons. One of the, most important is that the data created by a computer system using one coding scheme cannot be directly accessed and used by another computer system using a different coding scheme. Generally, this is not a problem if both computers are microcomputers since both would most likely use ASCII code. And most microcomputer applications store data using this code. However, problems occur when data is shared between microcomputers and larger computers that use EBCDIC code. The data must be translated from one coding scheme to the other before processing can begin. Fortunately, special conversion programs are available to help with this translation.
Sunday, July 29, 2007
electronic data and instruction
Data and instructions are represented electrically with a binary, or two state, numbering system. ASCII, EBCDIC and Unicode are binary coding schemes. Have you ever wondered why it is said that we live in a digital world? It’s because computers cannot recognize information the same way you and I can. People follow instructions and process data using letters, numbers, and special characters. For example, if we wanted someone to add the numbers 3 and 5 together and record the answer, we might say “please add 3 and 5”. The system unit, however, is electronic circuitry and cannot directly process such a request.
Our voices create analog, or continuous signals, that vary to represent different tones, pitches and volume. Computers, however, can recognize only digital electronic signals. Before any processing can occur within the system unit, a conversion must occur from what we understand to what the system unit can electronically process.
What is the important fundamental statement you can make about electricity? It is simply this: it can be either on or off. Indeed, there are many forms of technology that can make use of this two- state on/ off, yes /no, present/absent arrangement. For instance a light switch may be on or off, or an electric circuit open or closed. A specific location on a tape or disk may have a positive charge or negative charge. This is the reason, then, that a two state or binary system is used to represent data and instructions.
The decimal system that we are all familiar with has 10 digits (0,1,2,3,4,5,6,7,8,9). The binary system, however, condition consists of only two digits – 0, and 1. Each 0 or 1 is called a bit – short for binary digit. In the system unit, the 0 can be represented by electrically being off and the 1 by electrically being on. In order to represent numbers, letters and special characters, bits, are combined into groups of eight called bytes. Each byte typically represents one character.
Our voices create analog, or continuous signals, that vary to represent different tones, pitches and volume. Computers, however, can recognize only digital electronic signals. Before any processing can occur within the system unit, a conversion must occur from what we understand to what the system unit can electronically process.
What is the important fundamental statement you can make about electricity? It is simply this: it can be either on or off. Indeed, there are many forms of technology that can make use of this two- state on/ off, yes /no, present/absent arrangement. For instance a light switch may be on or off, or an electric circuit open or closed. A specific location on a tape or disk may have a positive charge or negative charge. This is the reason, then, that a two state or binary system is used to represent data and instructions.
The decimal system that we are all familiar with has 10 digits (0,1,2,3,4,5,6,7,8,9). The binary system, however, condition consists of only two digits – 0, and 1. Each 0 or 1 is called a bit – short for binary digit. In the system unit, the 0 can be represented by electrically being off and the 1 by electrically being on. In order to represent numbers, letters and special characters, bits, are combined into groups of eight called bytes. Each byte typically represents one character.
High capacity floppy disks
while the traditional floppy disk is very reliable and still widely used to store data , it has very limited capacity. While 1.44 MB is fine for many text and spreadsheet files, it is not sufficient to hold larger files. For example, many Powerpoint presentation files exceed 1.44 MB. Most multimedia applications require even greater capacity. High capacity disks, also known as floppy disk cartridges, are rapidly replacing the traditional floppy disk. Like the traditional floppy, the high capacity disks are 3 ½ inches in diameter. However, they are able to store more information, are thicker, and require special disk drives. The three best known high capacity disks are Zip, HiFD, and SuperDisks.
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