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Class Library access to Internet sites with objectionable content. The Supreme Court upheld this law in 2003 (United States v. American Library Association). Circularity circularity the problem that arises when a computer cannot finish a task until it has already finished it—an impossible situation. For example, in a spreadsheet, a circularity problem arises if you enter [...]

Chicago Chicago the code name by which Windows 95 was identified before its release. Compare CAIRO; LONGHORN; MEMPHIS; WHISTLER; BLACKCOMB. child  child an object created with the properties of another object (called the PAR- ENT). Updating the properties of the parent object affects the children, but changing the properties of the child does not affect the parent. See VECTOR GRAPHICS; OBJECT-ORIENTED PROGRAMMING. child process child process a [...]

CCD CCD image sensor 82 FIGURE 51. CCD image sensor (in webcam with lens removed) CCD image sensor CCD image sensor (charge-coupled device) the electronic image sensor most often used in digital cameras, video cameras, and scanners. A lens forms an image on an array of cells (Figure 52), each of which contains a photoconductive layer that [...]

bring forward; forward one comparable commands that send the selected object down one layer. See also ARRANGE; BRING TO FRONT; TO FRONT; DRAW PROGRAM; SEND BACKWARD; BACK ONE; SEND TO BACK; TO BACK. bring to front; to front comparable commands that send the selected object to the top layer. See also ARRANGE; BRING FORWARD; FORWARD ONE; DRAW PROGRAM; SEND BACKWARD; BACK ONE; SEND TO BACK; TO BACK. FIGURE 40. [...]

Binary Number 21 × 13 63 21 273 First, find 3 × 21. Then, find 10 × 21, and add these two results together to get the final product. Note that the product has more digits than either of the two original numbers. You can follow the same procedure to multiply two binary numbers: 10101 × 01101 10101 00000 10101 10101 [...]

BAT file (batch file) Baseband baseband the range of frequencies needed to convey a signal itself, with- out a higher-frequency carrier. For example, the video signal from a TV camera is a baseband signal. When modulated onto a radio-frequency carrier so that it can share a cable with many other TV signals, it becomes a broadband [...]

AWK AWK a programming language for scanning text files and processing lines or strings that match particular patterns, now largely superseded by Perl. AWK was developed by A. V. Aho, P. J. Weinberger, and B. W. Kernighan, and the name “AWK” is an acronym composed of their ini- tials. Compare PERL; PYTHON; REXX. AWT AWT (Abstract Window Toolkit) a set of tools [...]

ASC 30 walk, for instance, and to find and grasp objects—even though human beings do these things naturally. AI also includes natural language processing—getting computers to understand speech, or at least typewritten input, in a language such as English. In the late 1950s it was expected that computers would soon be programmed to accept natural-language input, [...]

alpha alpha (α) a measure of the opacity, or visibility, of an object in a graphical image. A transparent object has an alpha of 0 and is invisible; most objects have an alpha of 1 and completely cover the objects behind them. alpha channel (in paint programs) a CHANNEL that defines a selection. Instead of specifying a color of [...]

ALGOL ALGOL (Algorithmic Language) a pair of programming languages that had a strong impact on programming language design. The first, ALGOL 60 (developed by an international committee around 1960), was an immediate ancestor of Pascal and introduced many Pascal-like fea- tures that have been adopted by numerous other languages, including: • recursion; • begin and end keywords to allow grouping [...]

9 accessibility acceptable-use policy a policy established by the owner of a computer sys- tem, or by an Internet service provider, concerning acceptable use of the computer and network facilities. Acceptable-use policies should gener- ally include the following points: 1. Users are accountable for what they do. Deliberate snooping, harassment, or interference with other users will [...]

Conceptually a computer system is made up of layers. The hardware is the lowest level in all such systems. The kernel running at the next level uses the hardware instructions to create a set of system call for use by outer layers. The system programs above the kernel are therefore able to use either system [...]

The region in the memory that a process is allowed to access is known as process address  space. To ensure correct operation of a computer system, we need to ensure that a process cannot access memory outside its address space. If we don’t do this then a process may, accidentally or deliberately, overwrite the address [...]

Single-user systems A computer system that allows only one user to use the computer at a given time is known as a single-user  system. The goals of such systems are maximizing user convenience and responsiveness, instead of maximizing the utilization of the CPU and peripheral devices. Single-user systems use I/O devices such as keyboards, mice, [...]

There are two views about this. The top-down view is that it is a program that acts as an intermediary between a user of a computer and the computer hardware, and makes the computer system convenient to use. It is because of the operating system that users of a computer system don’t have to deal [...]

Templates are a major code reuse feature. History of C++ language reveals that the template feature was introduced later, relative to other features. But it is a very important feature. We will realize that it makes a lot more sense to keep total code base very small and very concise. It also helps ensure that [...]

Pointers Pointer is a special type of variable that contains a memory address. It is not a variable that contains a value, rather an address of the memory that is contained inside a pointer variable. In C++ language, variables can be without type. Either we can have a void pointer or these can be typed. [...]

Constructor is a special function, called whenever we instantiate an object of a class. If we do not define a constructor function in a class, the C++ provides a default constructor. It is executed at the time of instantiating an object. To understand the basic function of constructor, we have to go back. While writing [...]

This lecture is a sequel of the previous discussion on ‘Classes’ and ‘Objects’. The use of ‘classes and objects’ has changed our way of thinking. Instead of having function- oriented programs i.e. getting data and performing functions with it, we have now data that knows how to manipulate itself. This way, now the programming is [...]

The first problem may be the unreferenced memory. To understand this phenomenon, suppose,  we  allocate memory from  heap and  there  is  a  pointer pointing to  this memory. However,  it  is  found  that this pointer does  not exist any more in  our program. What will happen to the memory we had allocated. That chunk of memory [...]

Earlier, whenever we declared arrays, the size of the arrays was predefined. For example we declared an array of size 100 to store ages of students. Besides, we need 20, 25 or 50 number of students to store their ages. The compiler reserves the memory to store 100 integers (ages). If there are 50 integers [...]

We have so far been dealing with bytes using different data types. In this lecture, we will see what a bit is? Bit is the basic unit of memory. Eight bits form a byte. As you know that data is stored in computers in 0’s and 1’s form. An integer uses four bytes and the [...]

We have four basic data types i.e. char, int, float and double. Character strings are arrays of characters. Suppose, there is a word or name like Amir to store in one entity. We cannot store it into a char variable because it can store only one character. For this purpose, a character array is used. [...]

In general, we should minimize the use of break statement in loops. The switch statement is an exception in this regard where it is necessary to use the break statement after every case. Otherwise, there may be a logical error. While writing loops, we should try to execute the loops with the condition test and [...]

There can be little doubt that the French elevators placed in the east and west piers to carry visitors to the first stage of the Tower had the important secondary function of saving face. That an engineer of Eiffel’s mechanical perception would have permitted their use, unless compelled to do so by the Exposition Commission, [...]

The Hydraulic Elevator The rope-geared hydraulic elevator, which was eventually to become known as the “standard of the industry,” is generally thought to have evolved directly from an invention of the English engineer Sir William Armstrong (1810-1900) of ordnance fame. In 1846 he developed a water-powered crane, utilizing the hydraulic head available from a reservoir [...]

Elevator Development before the Tower While power-driven hoists and elevators in many forms had been used since the early years of the 19th century, the ever-present possibility of breakage of the hoisting rope restricted their use almost entirely to the handling of goods in mills and warehouses.[3] Not until the invention of a device which [...]

From Goosse Quills to Fountain Pens and Lead Pencils Whenever there was a convenient goosepond on the way to school, the children of less than one hundred years ago used to stop there to hunt for goose quills. They carried these to the teacher, and with his penknife—which took its name from the work it [...]

How Indian Rubber Goes Through the Factory Courtesy U. S. Tire Co. Splitting Para biscuits, mixing the rubber, rolling the rubber fabric on cylinders, and building tires on the tire machines. There are many little conveniences made of rubber which we should greatly miss, such as the little tips put into pencil ends for erasing [...]

The Yale Lock which comes from America, works on a quite different system. Its most noticeable feature is that it permits the use of a very small key, though the number of combinations possible is still enormous (several millions). In our illustrations (Figs. 219, 220, 221) we show the mechanism controlling the turning of the [...]