Chapter-4a(transforming Data Into Information)

Chapter:4A Processing Data

Bits A binary digit. In the computer, electronics, and communications fields, “bit” is generally understood as a shortened form of “binary digit.” In a numerical binary system, a bit is either a 0 or 1. Bits are generally used to indicate situations that can take one of two values or one of two states, for example, on and off, true or false, or yes or no. If, by convention, 1 represents a particular state, then 0 represents the other state. For example, if 1 stands for “yes,” then 0 stands for “no.”

Bytes It is made up of eight binary digits (bits).

TEXT CODES ASCII Acronym for the American Standard Code for Information Interchange. Pronounced ask-ee, ASCII is a code for representing English characters as numbers, with each letter assigned a number from 0 to 127. For example, the ASCII code for uppercase M is 77. Most computers use ASCII codes to represent text, which makes it possible to transfer data from one computer to another.

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ASCII The standard ASCII character set uses just 7 bits for each character. There are several larger character sets that use 8 bits, which gives them 128 additional characters. The extra characters are used to represent non-English characters, graphics symbols, and mathematical symbols. Several companies and organizations have proposed extensions for these 128 characters.

EBCDIC Abbreviation of Extended BinaryCoded Decimal Interchange Code. Pronounced eb-sih-dik, EBCDIC is an IBM code for representing characters as numbers. Although it is widely used on large IBM computers

UNICODE A standard for representing characters as integers. Unlike ASCII, which uses 7 bits for each character, Unicode uses 32 bits, which means that it can represent more than 4 billion unique characters. This is a bit of overkill for English and Western-European languages, but it is necessary for some other languages, such as Greek, Chinese and Japanese. Many analysts believe that as the software industry becomes increasingly global, Unicode will eventually replace ASCII as the standard character coding format.

How Computer Process Data

CPU The CPU is the brains of the computer. Sometimes referred to simply as the processor or central processor, the CPU is where most calculations take place. In terms of computing power, the CPU is the most important element of a computer system.

CPU Two typical components of a CPU are: The arithmetic logic unit (ALU), which performs arithmetic and logical operations. The control unit (CU), which extracts instructions from memory and decodes and executes them, calling on the ALU when necessary.

Control Unit A computer is a device that accepts information and manipulates it for some result based on a program or sequence of instructions on how the data is to be processed.

Dual-Core Processor Dual-core refers to a CPU that includes two complete execution cores per physical processor. It combines two processors and their caches and cache controllers onto a single integrated circuit (silicon chip). It is basically two processors, in most cases, reside side-by-side on the same die.

ALU In computing, an arithmetic logic unit (ALU) is a digital circuit that performs arithmetic and logical operations. The ALU is a fundamental building block of the central processing unit of a computer, and even the simplest microprocessors contain one for purposes such as maintaining timers.

Simple Operations by ALU Most ALUs can perform the following operations: Integer arithmetic operations (addition, subtraction, and sometimes multiplication and division) ------Bitwise logic operations (AND, NOT, OR, XOR) -----Bit-shifting operations (shifting or rotating a word by a specified number of bits to the left or right, with or without sign extension).

ALU

MEMORY

Nonvolatile memory. Non-volatile memory, NVM or non-volatile storage, is computer memory that can retain the stored information even when not powered. Examples of non-volatile memory include readonly memory, flash memory, most types of magnetic computer storage devices (e.g. hard disks, floppy disk drives, and magnetic tape), optical disc drives.

Flash Memory. A very popular non-volatile, rewritable memory chip. Evolving from the EEPROM chip, flash was invented by Toshiba and named after its ability to erase a block of a data "in a flash." Extremely durable, flash is widely used for storage modules such as USB drives and digital camera memory cards .

Volatile memory Volatile memory, also known as volatile storage or primary storage device, is computer memory that requires power to maintain the stored information

SIMM Acronym for single in-line memory module, a small circuit board that can hold a group of memory chips. Typically, SIMMs hold up to eight (on Macintoshes) or nine (on PCs) RAM chips. On PCs, the ninth chip is often used for parity error checking. Unlike memory chips, SIMMs are measured in bytes rather than bits. SIMMs are easier to install than individual memory chips. .

Parity Checking Assume, for example, that two devices are communicating with even parity (the most common form of parity checking). If the number of set bits is even, it sets the parity bit to 0; if the number of set bits is odd, it sets the parity bit to 1. In this way, every byte has an even number of set bits. On the receiving side, the device checks each byte to make sure that it has an even number of set bits. If it finds an odd number of set bits, the receiver knows there was an error during transmission

SIMM

DIMM Short for dual in-line memory module, a small circuit board that holds memory chips. A single in-line memory module (SIMM) has a 32-bit path to the memory chips whereas a DIMM has 64-bit path. Because the Pentium processor requires a 64-bit path to memory, you need to install SIMMs two at a time. With DIMMs, you can install memory one DIMM at a time.

Registers A, special, high-speed storage area within the CPU. All data must be represented in a register before it can be processed. For example, if two numbers are to be multiplied, both numbers must be in registers, and the result is also placed in a register. (The register can contain the address of a memory location where data is stored rather than the actual data itself. The number of registers that a CPU has and the size of each (number of bits) help determine the power and speed of a CPU. For example a 32-bit CPU is one in which each register is 32 bits wide. Therefore, each CPU instruction can manipulate 32 bits of data.

Memory and Computing Power

The computers Internal Clock Also called clock rate, the speed at which a microprocessor executes instructions. Every computer contains an internal clock that regulates the rate at which instructions are executed and synchronizes all the various computer components. The CPU requires a fixed number of clock ticks (or clock cycles) to execute each instruction. The faster the clock, the more instructions the CPU can execute per second. Clock speeds are expressed in megahertz (MHz) or gigahertz ((GHz).

BUS A collection of wires through which data is transmitted from one part of a computer to another. You can think of a bus as a highway on which data travels within a computer. When used in reference to personal computers, the term bus usually refers to internal bus. This is a bus that connects all the internal computer components to the CPU and main memory. There's also an expansion bus that enables expansion boards to access the CPU and memory. All buses consist of two parts -- an address bus and a data bus. The data bus transfers actual data whereas the address bus transfers information about where the data should go. The size of a bus, known as its width, is important because it determines how much data can be transmitted at one time. For example, a 16-bit bus can transmit 16 bits of data, whereas a 32-bit bus can transmit 32 bits of data. Every bus has a clock speed measured in MHz. A fast bus allows data to be transferred faster, which makes applications run faster. On PCs, the old ISA bus is being replaced by faster buses such as PCI.

ISA BUS (Pronounced as separate letters or as eyesa). Short for Industry Standard Architecture bus, the bus architecture used in the IBM PC/XT and PC/AT. The AT version of the bus is called the AT bus. Starting in the early 90s, ISA began to be replaced by the PCI local bus architecture. Most computers made today include both an AT bus for slower devices and a PCI bus for devices that need better bus performance..

PCI BUS Short for Peripheral Component Interconnect, a local bus standard developed by Intel Corporation. Most modern PCs include a PCI bus . PCI is also used on newer versions of the Macintosh computer. PCI is a 64-bit bus, though it is usually implemented as a 32-bit bus. It can run at clock speeds of 33 or 66 MHz.

Local Bus Local buses can support only a few devices, they provide very fast output.

Address Bus It is a set of wires which connects only the CPU and RAM and carries only memory address.

AGP Short for Accelerated Graphics Port, an interface specification developed by Intel Corporation. AGP is based on PCI, but is designed especially for the throughput demands of 3-D graphics. Rather than using the PCI bus for graphics data, AGP introduces a dedicated point-to-point channel so that the graphics controller can directly access main memory.

USB Short for Universal Serial Bus, an external bus standard that supports data transfer rates of 12 Mbps. A single USB port can be used to connect up to 127 peripheral devices, such as mice, modems, and keyboards. USB also supports Plug-and-Play installation and hot plugging.

Plug and Play Refers to the ability of a computer system to automatically configure expansion boards and other devices. You should be able to plug in a device and play with it, without worrying about setting DIP switches, jumpers, and other configuration elements.

Cache Memory A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations.

Cache Memory When a program is running and the CPU needs to read a data from RAM,, the CPU checks first to see whether the data is in cache memory. If the data is not there, the CPU reads data from RAM into its register, but it also loads a copy of the data into cache memory. The next time the CPU needs the data, it finds it in the cache memory and saves the time needed to load then data from RAM.

Cache Memory