2.1.1+Systems+Fundamentals

2.1 Basics: hardware and networks 2.1.1 Systems fundamentals

Social and ethical issues Students must study and evaluate the social and ethical issues involved in the use of IT systems. These may include: • the economic value of information • environmental issues related to the production of computer components and supplies • environmental issues related to the disposal of obsolete hardware and computer supplies • health issues and ergonomics related to the use of hardware • password protection, security, biometrics and authorized access • issues related to viruses on both stand-alone and network systems • greater dependence of organizations on IT  • increase in teleworking and the virtual office • the need for ongoing training and retraining • the economic and psychological implications of planned IT obsolescence in hardware, software and services, which has been forced on consumers by the IT industry • organizational policies and standards, for example, e-mail, surveillance and monitoring policies.

Syllabus details Knowledge of technology In order to study and evaluate the social and ethical issues involved in the use of IT systems, the student must have an understanding of related technological concepts. These may include: • key terms—data, information, hardware components, for example, input devices, output devices, processing, storage, memory (RAM, ROM), MHz, dpi, bit, KB, MB, GB, TB, ASCII, compatibility, OCR, OMR, bar code, baud, verification and validation, encryption/decryption, firewall, virus, Trojan horse, worm, logic bomb, platform, peripheral • use, advantages and disadvantages of analogue and digital data • operating systems (multitasking, boot) and utilities, for example, defragment, disk format, virus scan programs • responsible computer use (for example, regular back-ups, virus checking, security, storage, housekeeping) • a responsible and systematic approach to implementing or upgrading IT systems, for example, analysis, design, implementation, testing, evaluation, training, policies and standards.


 * Chapter 2 **


 * ** architecture ** || Design that determines how individual components of the CPU are put together on the chip. More generally used to describe the way individual components are put together to create a complete computer system. ||
 * ** ASCII ** || American Standard Code for Information Interchange, a code that represents characters as 8-bit codes. Allows the binary computer to work with letters, digits, and special characters. ||
 * ** backward compatible ** || Able to run software written for older CPUs. Also, when referring to a software program, able to read and write files compatible with older versions of the program. ||
 * ** bay ** || An open area in the system box for disk drives and other peripheral devices. ||
 * ** binary ** || A choice of two values, such as yes and no or zero and one. ||
 * ** bit ** || Binary digit, the smallest unit of information. A bit can have two values: 0 or 1. ||
 * ** bus ** || Group of wires on a circuit board. Information travels between components through a bus. ||
 * ** byte ** || Grouping of 8 bits. ||
 * ** central processing unit (CPU) ** || Part of the computer that processes information, performs arithmetic calculations, and makes basic decisions based on information values. ||
 * ** cluster ** || A grouping of multiple processors or servers to, for example, improve graphic rendering speeds or increase reliability. ||
 * ** compatible (compatibility) ** || The ability of a software program to run on a specific computer system. Also, the ability of a hardware device to function with a particular type of computer. ||
 * ** data ** || Information in a form that can be read, used, and manipulated by a computer. ||
 * ** digit ** || A discrete, countable unit. ||
 * ** digital ** || Information made up of discrete units that can be counted. ||
 * ** expansion slot ** || An area inside the computer's housing that holds special- purpose circuit boards. ||
 * ** file ** || An organized collection of related information stored in a computer- readable form. ||
 * ** GB (gigabyte) ** || Approximately 1000MB. ||
 * ** information ** || Anything that can be communicated. ||
 * ** input device ** || Device for accepting input, such as a keyboard. ||
 * ** KB (kilobyte) ** || About 1000 bytes of information. ||
 * ** MB (megabyte) ** || Approximately 1000K, or 1 million bytes. ||
 * ** memory ** || Stores programs and the data they need to be instantly accessible to the CPU. ||
 * ** microprocessor ** || Now known as a personal computer. ||
 * ** motherboard ** || The circuit board that contains a computer's CPU. Also called a system board. ||
 * ** multiprocessing ** || Employing two or more microprocessors in a computer in order to improve overall performance. Also known as symmetric multiprocessing. ||
 * ** nonvolatile memory ** || Memory that is not lost when the computer is turned off. An example is the read-only memory that contains start-up instructions and other critical information. ||
 * ** optical computer ** || A potential future alternative to silicon-based computing, in which information is transmitted in light waves rather than in electrical pulses. ||
 * ** output device ** || Device for sending information from the computer, such as a monitor or printer. ||
 * ** parallel processing ** || Using multiple processors to divide jobs into pieces and work simultaneously on the pieces. ||
 * ** PC card ** || A credit-card-size card that can be inserted into a slot to expand memory or add a peripheral to a computer; commonly used in portable computers. Sometimes called by its original name, PCMCIA. ||
 * ** peripheral ** || An external device, such as a keyboard or monitor, connected via cables to the system central processing unit. ||
 * ** PB (petabyte) ** || The equivalent of 1024 terabytes, or 1 quadrillion bytes. ||
 * ** port ** || Socket that allows information to pass in and out. ||
 * ** processor ** || Part of the computer that processes information, performs arithmetic calculations, and makes basic decisions based on information values. ||
 * ** RAM (random access memory) ** || Memory that stores program instructions and data temporarily. ||
 * ** ROM (read-only memory) ** || Memory that includes permanent information only. The computer can only read information from it; it can never write any new information on it. ||
 * ** storage device ** || Long-term repository for data. Disks and tape drives are examples. ||
 * ** symmetric multiprocessing ** || See multiprocessing. ||
 * ** system bus ** || A group of wires that transmits information between components on the motherboard. ||
 * ** TB (terabyte) ** || Approximately 1 million megabytes. ||
 * ** Unicode ** || A 65,000-character set for making letters, digits, and special characters fit into the computer's binary circuitry. ||

CPU
The **Central Processing Unit** (**CPU**) or **processor** is the portion of a computer system that carries out the instructions of a computer program, and is the primary element carrying out the computer's functions. This term has been in use in the computer industry at least since the early 1960s (Weik 2007). The form, design and implementation of CPUs have changed dramatically since the earliest examples, but their fundamental operation remains much the same. Early CPUs were custom-designed as a part of a larger, sometimes one-of-a-kind, computer. However, this costly method of designing custom CPUs for a particular application has largely given way to the development of mass-produced processors that are made for one or many purposes. This standardization trend generally began in the era of discrete transistor mainframes and minicomputers and has rapidly accelerated with the popularization of the integrated circuit (IC). The IC has allowed increasingly complex CPUs to be designed and manufactured to tolerances on the order of nanometers. Both the miniaturization and standardization of CPUs have increased the presence of these digital devices in modern life far beyond the limited application of dedicated computing machines. Modern microprocessors appear in everything from automobiles to cell phones and children's toys.

Arithmetic/logic unit (ALU)
The ALU is capable of performing two classes of operations: arithmetic and logic.[24] The set of arithmetic operations that a particular ALU supports may be limited to adding and subtracting or might include multiplying or dividing, trigonometry functions (sine, cosine, etc) and square roots. Some can only operate on whole numbers (integers) whilst others use floating point to represent real numbers—albeit with limited precision. However, any computer that is capable of performing just the simplest operations can be programmed to break down the more complex operations into simple steps that it can perform. Therefore, any computer can be programmed to perform any arithmetic operation—although it will take more time to do so if its ALU does not directly support the operation. An ALU may also compare numbers and return boolean truth values (true or false) depending on whether one is equal to, greater than or less than the other ("is 64 greater than 65?"). Logic operations involve Boolean logic: AND, OR, XOR and NOT. These can be useful both for creating complicated conditional statements and processing boolean logic. Superscalar computers may contain multiple ALUs so that they can process several instructions at the same time. Graphics processors and computers with SIMD and MIMD features often provide ALUs that can perform arithmetic on vectors and matrices.

Memory
Magnetic core memory was the computer memory of choice throughout the 1960s, until it was replaced by semiconductor memory. A computer's memory can be viewed as a list of cells into which numbers can be placed or read. Each cell has a numbered "address" and can store a single number. The computer can be instructed to "put the number 123 into the cell numbered 1357" or to "add the number that is in cell 1357 to the number that is in cell 2468 and put the answer into cell 1595". The information stored in memory may represent practically anything. Letters, numbers, even computer instructions can be placed into memory with equal ease. Since the CPU does not differentiate between different types of information, it is the software's responsibility to give significance to what the memory sees as nothing but a series of numbers. In almost all modern computers, each memory cell is set up to store binary numbers in groups of eight bits (called a byte). Each byte is able to represent 256 different numbers (2^8 = 256); either from 0 to 255 or -128 to +127. To store larger numbers, several consecutive bytes may be used (typically, two, four or eight). When negative numbers are required, they are usually stored in two's complement notation. Other arrangements are possible, but are usually not seen outside of specialized applications or historical contexts. A computer can store any kind of information in memory if it can be represented numerically. Modern computers have billions or even trillions of bytes of memory. The CPU contains a special set of memory cells called registers that can be read and written to much more rapidly than the main memory area. There are typically between two and one hundred registers depending on the type of CPU. Registers are used for the most frequently needed data items to avoid having to access main memory every time data is needed. As data is constantly being worked on, reducing the need to access main memory (which is often slow compared to the ALU and control units) greatly increases the computer's speed. Computer main memory comes in two principal varieties: random-access memory or RAM and read-only memory or ROM. RAM can be read and written to anytime the CPU commands it, but ROM is pre-loaded with data and software that never changes, so the CPU can only read from it. ROM is typically used to store the computer's initial start-up instructions. In general, the contents of RAM are erased when the power to the computer is turned off, but ROM retains its data indefinitely. In a PC, the ROM contains a specialized program called the BIOS that orchestrates loading the computer's operating system from the hard disk drive into RAM whenever the computer is turned on or reset. In embedded computers, which frequently do not have disk drives, all of the required software may be stored in ROM. Software stored in ROM is often called firmware, because it is notionally more like hardware than software. Flash memory blurs the distinction between ROM and RAM, as it retains its data when turned off but is also rewritable. It is typically much slower than conventional ROM and RAM however, so its use is restricted to applications where high speed is unnecessary. In more sophisticated computers there may be one or more RAM cache memories which are slower than registers but faster than main memory. Generally computers with this sort of cache are designed to move frequently needed data into the cache automatically, often without the need for any intervention on the programmer's part.

Input/output (I/O)
I/O is the means by which a computer exchanges information with the outside world. Devices that provide input or output to the computer are called peripherals. On a typical personal computer, peripherals include input devices like the keyboard and mouse, and output devices such as the display and printer. Hard disk drives, floppy disk drives and optical disc drives serve as both input and output devices. Computer networking is another form of I/O. Often, I/O devices are complex computers in their own right with their own CPU and memory. A graphics processing unit might contain fifty or more tiny computers that perform the calculations necessary to display 3D graphics. Modern desktop computers contain many smaller computers that assist the main CPU in performing I/O.

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