SCSI connections may connect both internal devices, which are inside the chassis of your computer and use the computer’s power supply, and external devices. Integrated derive Electronics (IDE) connections, on the other hand, are typically only internal and connect hard disks, CD-ROM derives, and other peripherals inside a PC. A PC motherboard can support two IDE controllers, and each controller in turn can support two devices (a master and a slave).
Thursday, June 26, 2008
Small Computer System Interface (SCSI)
The Small Comuter System Interface (SCSI) is built into all current models. You can connect as many as eight devices (ID numbers from 0 to 7) to the SCSI port, but one of them must be the computer itself with ID 7, and one is usually your internal hard disk with ID 0.
Framework for Multimedia Systems
The framework presented here provides an overall picture of the development of distributed multimedia systems from which a system architecture can be developed. The framework highlights the dominant feature of multimedia systems: the integration of multimedia computing and communications, including raditional telecommunications and telephony functions.
Low-cost multimedia technology is evolving to provide richer information processing and communications systems. These systems, though tightly interrelated, have distinct physical facilities, logical models, and functionality. Multimedia information systems extend the processing, storage, and retrieval capabilities of existing information systems by introducing new media data types, including image, audio, and video. These new data types offer perceptually richer and more accessible representations for many kinds of information. Multimedia communication systems extend I existing point-to-point connectivity by permitting synchronised multipoint group communications.
Introduction to Multimedia Technology
A complex weave of communications, electronics, and computer technologies is emerging to create a new multimedia fabric for the next decade. The nature of this cloth is still evolving as an assortment of industries-telecommunications, consumer electronics, computers, cable and broadcast television, and information providers-compete for the emerging market. The potentially biggest near-term market will be the home and consumer, as recent developments such as consumer-oriented computer products, interactive television, and video-on-demand suggest. However, in time many expect the new technologies to be as pervasive as today’s television and telephone and the impact to reach to the sum of computers, telecommunications, and electronics, touching all parts of society from industry to government, education to recreation.
The concepts behind what is emerging today date back to over four decades to a series of visionary thinkers who foresaw the evolution of computers towards richer personalised devices that would become an extension of the individual. In 1945 Vannevar Bush, then the Director of the Office of Scientific Research and Development in the U.S. government, suggested, that one of the future devices available for individuals would be a memex, “a device in which one stores all his books, records, and communications, and which is mechanised so that it can be consulted with exceeding speed and flexibility. It is an enlarged intimate supplement to his memory.” The memex would additionally be an associative device, so that related items could be easily located.
Multimedia Systems
Multimedia technology is breaking down the traditional boundaries between devices for computing, personal communications, and consumer entertainment. Major industries are rethinking their market strategy and forming a web of new alliances connecting entertainment, telecommunications, computing, publishing, and other global enterprises. Multimedia devices are expected to replace ubiquitous appliances such as the telephone and television and change many of the activities associated with them. The large scale of these trends and the many participants in these developments has added to the complexity of the possibilities. This chapter provides a contemporary account of the major technology forces affecting this convergence and identifies the significant near-term issues that lie ahead.
Entertainment
When the average person talks about consumer electronics, TV is what first comes to mind. Television is a very young industry. The first black and white broadcasts started in 1941.Color TV sets were not available at consumer prices until 1964. Cable TV was not widely available in most areas of the united States until the 1980s. Today, the average cable system has more than forty channels to choose from .CNN, MTV, HBO, and the like were not available in the 1960s and only just started in the 1970s,MTS stereo television broadcasts and stereo TV sets have only been available in the 1990s.In Europe and Japan commercial and cable TV has not flourished the way it has in the United States due to regulatory constraints and language barriers. Most countries have fewer than five TV channels.
Consumer electronics in the early 1980s introduced inexpensive home VCRs. The war between Beta and VHS was hot and heavy. Eventually VHS won due to JVC’s aggressive licensing and VHS’s eight-hour capability, The picture quality was poor, and the technology was inferior, but strong marketing won out. Camcorders, another recent innovation, have replaced the 8 mm and super8movie cameras in a very few years. The compact disc (CD) was introduced by philips and Sony in 1981.Today, it’s almost impossible to get a real record (as in LP). Similar changes have occurred in tape recording technology and electronic musical synthesisers.
Communications
In 1980, the Bell System in the United States was still a monopoly. On January 1, 1982, Judge Harold Green dissected the Bell System into Regional Bell Operating Companies (RBOCs), commonly referred to as “Baby Bells”. Bell Labs and Western Electric were also restructured (as American Bell and later renamed AT&T Consumer Products) so as not to have an unfair advantage with the Bell name. With deregulation in place, any number of companies could sell a telephone or provide long-distance service. Years later, most of the cheap $5 phones are a thing of the past. After the FCC opened up the 46-MHz band, use of cordless phones has grown significantly. The FCC has now also opened up a new 900 MHz band for cordless phones, which has extended range and less interference with radio-controlled toys than the 49 MHz band.
In the rest of the world, most countries still have a government monopoly on the phone system, though this is changing because of influence from the U.S. market. The united Kingdom is probably the most progressive non-U.S. market. Cellular phones have been terrified so inexpensively in the united kingdom that most people own cellular phones, Many U.S. companies, such as US West, have set up U.K. subsidiaries to sell cable TV and phone service at 15 percent lower rates than the local monopoly, The monopoly position does have its advantages however, For new technology to take hold in the United States, each of the RBOCs must endorse the new technology and the market must show a need. In other countries, the PTT may proclaim that a certain technology will be adopted (like integrated services Digital network (ISDN) for instance), and there is a government mandate to make it happen. For this reason, Europe is much father ahead in deploying ISDN than the united States.
In the united States, the Federal Communication commission (FCC) has a reasonable scope of influence to open doors for multimedia communications. In 1992, the FCC allocated a new frequency band at 218-219 MHz for interactive video applications. This new band will be used for a nationwide interactive TV service called TV-Answer, which is based on a radio frequency (RF) cellular-like modem. Since most cable networks today are transmit- only. This new RF channel can provide the return communications path for these new services. Home shopping is one obvious use of this technology.
Digital signature
Digital signature is a sequence of bits that are calculated mathematically while signing a given document. Since it is easy to copy, alter or move a file on computers without leaving any trail, one needs to be very careful in designing a signature scheme. In keeping with the properties of a handwritten signature, a digital signature should depend on some secret known only to the signer and on the content of the message should be able to distinguish between a forgery and a valid signature without requiring the signer to reveal any secret information. A general digital scheme consists of three algorithms:
1. A key generation algorithm
2. A signing algorithm
3. A verification algorithm
Cryptography: The process or skill of communicating in or deciphering secret writings or ciphers.
Working of digital signature:
Public key cryptography gives reliable method for digital signing and signature verification system based on public/private key pairs. A person can sign a given digital message with private key. The two steps involved are:
1. Calculate the hash value
In the first step of the process, a hash value of the message is calculated by applying some cryptographic hashing algorithm. The calculated hash value is a sequence of bits, usually with affixed length, extracted in some manner from the message. All reliable algorithms for message digest calculation apply such mathematical that when just a single bit from the input message is changed, a completely different digest is obtained.
2. Calculate the digital signature
In the second step of digitally signing a message, the information obtained in the first step hash-value of the message is encrypted with the private key of the person who signs the message and thus an encrypted hash-value, also called digital signature is obtained.
Verifying signed data
A digital signature is associated with a X.509 certificate which contains the sender’s public key. This key is used to decrypt the digital signature into the original hash value on the recipient’s computer. To verify the digital signature, the same hashing algorithm is used to generate a hash value based on the original data. The decrypted hash value is compared to the generated hash value. If the values match, the digital signature is valid.
1. Calculate the current hash value
2. Calculate the original hash value
3. Compare the current and the original hash-value
Benefits of digital signature:
Authenticity
Although digital signatures alone cannot prevent the content from being manipulated during delivery, using digital signatures provides a mechanism to detect tampering of it occurs. If the data is altered in any way after being digitally signed, the recipient can tell via properties of the signature that the data sent does not match the data received.
Acknowledgement
Data can be signed by the recipient as well as the sender. When a recipient signs the data and returns it to the sender, this signature is an acknowledgement. Digital signatures used in this way also provide no repudiation; the ability to prove that the data was sent by the signer.
Computers
The past ten years have brought much change to the world of computers, communications, and consumer products. Let’s review how far we’ve come. In 1980, personal computers were Apple IIs, Radio Shack TRS80s, Commodore Pets, and perhaps lesser known SOL20s and Exidy Sorcerers. Mini-computers were PDP 11/70 and VAX 11/780. Remarkably, punch cards were still around for those “big jobs.” The Commodore 64 appeared in 1981 and eventually won the home computer war against the likes of game machines such as the Atari 2600 VCS and Atari 5200, Mattel Intellivision, and others because it was a “real” computer instead of just a game machine. The C64 and its successor, the C128, also won over other similar home computers such as the Atari 400/800 and the various flavors of Radio Shack TRS80 models. This was a crazy time for the birth of the home computer. Many companies came and went in an attempt to provide the next hot consumer product.
In 1988, Sharp introduced an electronic organiser call the Wizard. With application programs on solid-state “credit cards”, the Wizard was basically an electronic address book and appointment scheduler. Palmtop computers were introduced in 1990 by Atari with the Portfolio and in 1991 by Hewlett-Packard with the 95LX. There were intended to take the Wizard concept one step further by adding a bigger display, a mini-QWERTY keyboard, and MS-DOS compatibility. Also in 1993 Hewlett-Packard upped the ante with a newer palmtop called 100LX and a subnotebook called the Omnibook 300.
The Newton and CD-I concepts are the first generation of the new convergence of computers, communications, and consumer products. They are not traditional televisions or phones or computers, but a hybrid of each. As new technologies become available, the fine line between these products gets even fuzzier.
WEB PAGE SET UP
Creation of a personal web page
A personal homepage is your means of putting your own information on the world wide web (www). A web page is nothing more than a text file written with special tags that format the contents, point to other pages, andinsert images and sounds. The tags arecalled hypertext markup language, or html.
There are a variety of ways to generate a web page:
• We may create our text file in many different ways using a text editor such as notepad (windows), simpletext(mac) or pico(unix).
• There are many software packages, such as dream weaver, that you can use to generate the html code for you. Additionally most word processing packages such as ms word, will usually save to the HTML format as well.
• We may choose to use a template (an existing frame of a document) and just fill in the details.
We will now discuss some of the basic HTML tags used:
HEAD TAG
1.BASEFONT Tag
It defines the font size to be used in html document.
2.BASE Tag
It is useful for setting some global parameters of an html document.
3.META Tag
This tag is used to include additional information about the document and can be used to pass additional information to a browser. There is no ending tag for and a document can have multiple tags. The attribute the meta tag are NAME, CONTENT, and HTTP-EQUIV.
CONTENT=”woodworking, cabinetmaking, handmade furniture”>
HTML and colors
There are two ways of defining colors in HTML documents. One involves simple color names , such as blue, cranberry, green, orange etc. However, since different browsers have different lists and since the definitions of individual colors may vary from browser to browser, we recommend using the color numbering scheme. For eg:
000000 means 00or no red, 00 of green, and 00of blue. So, 000000 represents black.# sign is to denote that they represent a color.
BODY TAG
The text and HTML code that goes between the body beginning and ending tags is rendered and displayed in the document area of the browser’s window.
1.TEXT color
The text attribute is used to change the default text color for an entire document.
2. BACKGROUND color
The BGCOLOR attribute is used to set the background of an HTML document to a single color.
3.HYPERLINK colors
Three attributes are used for changing the color of a hyperlink, where the color depends on the current state of the hyperlink. The three possible states are: unvisited, visited , and currently thinking of visiting.
LINK unvisited hyperlink
VLINK visited hyperlink
ALINK a hyperlink the user is thinking of visiting. The A stands for active hyperlink.
VLINK=”#808080”
ALINK=”#FFFF00”>
HTML FONT COLORS
It allows us to change the color of any portion of text.
I am going swimming today
WAP TO SHOW THE WORKING OF STATIC MEMBERS
#include
#include
class test
{private:
int code;
static int count;
public:
void setcode()
{code=++count;}
void showcode()
{cout<<"code--"<
static void showcount()
{cout<<"count--"<
};
int test::count;
void main()
{clrscr();
test t1,t2;
test::showcount();
t1.setcode();
t1.showcode();
test::showcount();
t2.setcode();
t2.showcode();
test::showcount();
getch();
UNFORMATTED INPUT OUTPUT
Overloaded operators >> and <<
The operators ‘>>’ and ’<<’ are overloaded respectively in the istream and ostream class. The following is the general format of reading data from the keyboard.
Cin>>variable1>> variable2>> ......>> variablenN
The input data are separated by white spaces and should match the type of data in the cin list. Spaces and new lines will be skipped. The operator reads the data character by character and assigns it to the indicated location. The reading variable will be terminated at the encounter of a white space or a character that does not match the destination type. For example:
Int code;
Suppose the following data is given as input: 4258D
The operator will read the characters up to 8 and the value 4258 is assigned to code.
Put() and get() functions
The classes istream and ostream define two member functions get() an put() respectively to handle the single character input/output operations. We can use both types of get() functions get(char*) and get(void) prototypes to fetch character including the blank spaces, tab and the newline character. The get(char*) version assigns the input character to its argument and the get(void) version returns the input character.
Example :
Char c;
Cin.get(c);
While(c != ‘\n’)
{
cout<<>
Cin.get(c);
}
This code reads and displays a line of text (terminated by a newline character). Remember, the operator >> can also be used to read a character. The above while loop will not work properly if the statement cin>>c; is used in place of cin.get(c);
The get(void) version is used as follows:
.....
Char c;
C=cin.get; // cin.get(c) replaced
.......
The value returned by the function get() is assigned to the variable c.
The function put(), a member of ostream class, can be used to output a line of text, charater by character. For example,
Cout.put(‘x’);
Displays the character x and
cout.put(ch);
displays the value of variable ch.
Getline() and write() functions
We can read and display a line of text more efficiently using the line oriented input output functions getline() and write(). The getline() function reads a whole line of text that end s with a newline character .
Syntax: cin.getline(line,size);
Eg: char name[20];
Cin.getline(name,20);
Assume that the input was
Bjarne stroustrup
This input will be read correctly and assigned to the character array name. Let us suppose the input was : object oriented programming
In this the input will be terminated after reading the first 19 characters.
The write() function displays an entire line and has the following form:
Cout.write(line,size)
The first argument line represents the name of the string to be displayed and the second argument size indicates the number of characters to display. Note that it does not stop dislaying the charaters automatically when the null character is encountered. If the size is greater than the length of line, then it displays beyond the bound of line.
Subscribe to:
Posts (Atom)