Technology Guide 1 Notes.doc

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Department
Administrative Studies
Course
ADMS 2511
Professor
Cristobal Sanchez- Rodriguez
Semester
Fall

Description
Technology Guide 1 - decisions about hardware focus on three interrelated factors: appropriateness for the task, speed and cost - advantageous to understand the basics about hardware - regardless of your major you will be using hardware throughout your career - you will have input concerning the hardware you are using, such as whether it is performing adequately for your needs, an dif not what the problems are that you are having with it and many other concerns - you will also have input into decisions such as when your financial area or organization upgrades its hardware - the budget for hardware sometimes is allocated to functional areas or departments, meaning that you might be making hardware decisions yourself Hardware: physical equipment used for the input, processing, output and storage activities of a computer system Consists of the following: - Central processing unit (CPU): manipulates the data and controls the tasks performed by the other compnents - Primary Storage: temporarily stores data and program instructions during processing - Secondary Storage: external to the CPU, stores data and programs for future use - Input Technologies: accept data, and instructions and convert them to a form the computer can understand - Output technologies: present data and information in a form people can understand - Communication Technologies: provide for the flow of data from external computer networks (e.g. the internet and intranets) to the CPU and from the CPU to computer networks The Central Processing Unit - the central processing unit (CPU): performs the actual computation or ‘number crunching’ inside any computer - the CPU is a microprocessor (for example an Itanium 2 by Intel) made up of millions of microscopic transistors embedded in a circuit on a silicon wafer or chip - microprocessors often called chips - microprocessor has different parts which perform different functions: - the Control Unit: sequentially accesses program instructions, decodes them, and controls the flow of data to and from the ALU, the registers, the caches, primary storage, secondary storage and various output devices - the Arithmetic Logic Unit (ALU): performs the mathematical calculations and makes logical comparisons - the Registers: are high speed storage areas that store very small amounts of data and instructions for short periods of time How the CPU works - in the cpu, inputs enter and are stored until needed - when needed, they are retrieved and processed and the output is stored and then delivered somewhere - the inputs consist of data and brief instructions about what to do with the data. These instructions come from software in other parts of the computer. Data might be entered by the user through the keyboard for example, or read from a data file in another part of the computer. The inputs are stored in registers until they are sent to the next step in the processing - data and instructions travel in the chip via electrical pathways called buses. The size of the bus – analogous to the width of a highway – determines how much information can flow at any time. - the control unit directs the flow of the data and instructions within the chip - the arithmetic logic unit (ALU) receives the data and instructions from the registers and makes the desired computation. The data and instructions have been translated into binary form that is only 0’s and 1’s. the CPU can process only binary data. - The data in its original form and the instructions are sent to storage registers and then are sent back to a storage place outside the chip, such as the computers hard drive. Meanwhile the transformed data goes to another register and then on to other parts of the computer (to the monitor for display or to storage for example) - This cycle of processing known as a Machine Instruction Cycle, occurs billions of times per second. - processing speed depends on clock speed, word length, bus width and the number of transistors on the chip - the clock speed is the preset speed of the clock that times all chip activities, measured in megahertz (MHz millions of cycles per second) and gigahertz (GHz billions of cycle per second) - the word length is the number of binary units, or bits (0’s and 1’s) that the CPU can process in one machine cycle - current chips can handle 64 bit word lengths, meaning that a chip can process 64 bits of data in one machine cycle. Larger the word length the faster the chip. - the bus width is the size of the physical paths down which the data and instructions travel as electrical impulses. The wider the bus, the more data that can be moved and the faster the processing - the distance between transistors is known as line width which is expressed in nanometers (billonths of a metre) - creating CPU;s with 45 nanometre line widths (0.45 microns) enabling the chip to have one billion transistors - the smaller the line width, the more transistors that can be packed onto a chip, and the faster the chip Advances in Microprocessor Design - innovations in chip designs are coming at a faster and faster rate as described by Moore’s Law - Gordon Moore (1965) co founder of intel corporation, predicted that microprocessor complexity would double approximately every two years - advances predicted from Moore’s Law come mainly from the following changes: - producing increasingly miniaturized transistors - making the physical layout of the chip’s components as compact and efficient as possible - using materials for the chip that improve the conductivity (flow) of electricity. Chips traditionally have been made of silicon, which is a semiconductor of electricity, that is electrons can flow through it at a certain rate. Materials such as gallium arsenide and silicon germanium allow even faster electron travel, although they are more expensive - placing multiple processors on a single chip. Chips with more than one processor are called multicore chips. For example, the Cell chip, produced by a consortium of Sony, Toshiba, and IBM contains nine processors. The cell chip enables graphics rich computing, and is also used in TV sets and home theatres capable of downloading and showing large numbers of high definition programs. A floating point operation (FLOP) is an arithmetic operation performed on floating point numbers (which contain a fractional part, such as a decimal). Measuring the number of floating point operations per second is measure of the computer’s performance, similar to the number of instructions per second. - in addition to increased speeds and performance, Moore’s Law has had an impact on costs for example in 1997 monitor cost about $4000, but now in 2007 it costs $1700. - although organizations certainly benefit from microprocessors that are faster, they also benefit from chips that are less powerful but are smaller and less expensive - these chips known as microcontrollers, are embedded in countless products and technologies, from cellular telephones to toys to automobile sensors. - microprocessors and microcontrollers are similar except that microcontrollers usually cost less and work in less demanding applications - such smaller systems enable many new applications for example, sensors have been placed in youths hockey helemets to study the effect of concussions during hockey games - the information is sent to small portable receivers in the arena - also microcontrollers automate toys, including stuffed animals and lego robots. Computer Memory - a computers memory can affect the types of programs it can run, the work it can do, its speed, the cost of the machine, and the cost of processing data - there are two basic categories of computer memory, the first is primary storage. - it is called ‘primary’ because it stores small amounts of data and information that will be used immediately by the CPU - the second is secondary storage which stores much larger amounts of data and information (an entire software program for example) for extended periods of time Memory Capacity - CPU’s process only binary units – 0’s and 1’s- which are translated through computer languages into bits - a particular combination of bits represents a certain alphanumeric character or a simple mathematical operation - eight bits are needed to represent any one of these characters - the eight bit string is known as a byte - the storage capacity of a computer is measured in bytes - bits typically are used as units of measure only for telecommunications capacity, as in how many million bits per second can be sent through a particular medium - the hierarchy of terms used to describe memory capacity is as follows: - Kilobyte: kilo means one thousand, so a kilobyte (KB) is a approx 1000 bytes (precisely 1024 bytes) - Megabyte: mega means one million, so a megabyte (MB) is approx one million bytes. Most personal computers have hundreds of megabytes of RAM memory - Gigabyte: giga means one billion, so a gigabyte (GB) is approx one bullion bytes. The storage capacity of a hard drive (type of secondary storage) in modern personal computers is hundreds of gigabytes. - Terabyte: a terabyte (TB) is approx 1000 gigabytes or one trillion bytes. - Petabyte: a petabyte (PB) is approx 1000 terabytes or one quadrillion bytes - Exabyte: an Exabyte (EB) is approx 1000 petabytes or one quintillion bytes - Zettabyte: (ZB) approx 1000 exabytes or one sextillion bytes - if your computer has 320 GB of storage capacity on its hard drive it can store approx 320 billion bytes of data. - if the average page of text has about 2000 bytes then your hard drive could store some 160 million pages of text Primary Storage: - primary storage or main memory, stores three types of information for very brief periods of time (1) data to be processed by the CPU, (2) instructions for the CPU as to how to process the data and (3) operating system programs that manage various aspects of the computers operation. - primary storage takes palce in chips mounted on the computers main circuit board, called the motherboard which are located as close as physically possible to the CPU chips - as with the CPU, all the data and instructions in primary storage have been translated into binary code - there are four main types of primary storage: (1) registers (2) random access memory (RAM) (3) cache memory and (4) read only memory (ROM) - logic of primary storage is that those components that will be used immediately are stored in very small amounts as close to the CPU as possible - as with CPU chip design the shorter the distance the electrical impulses (data) have to travel, the faster they can be transported and processed. 1. Registers: - part of the CPU - have the least capacity, storing extremely limited amounts of instructions and data only immediately before and after processing 2. Random Access Memory: - is the part of primary storage that holds a software program and small amounts of data for processing - when you start most software programs on your computer (such as Microsoft Word), the entire program is brought from secondary storage into RAM. - as you use the program, small parts of the programs instructions and data are sent into the registers and then to the CPU - compared with the registers, RAM stores more information and is located farther away from the CPU - however when compared with secondary storage, RAM stores less information and is much closer to the CPU - getting data and instructions as close to the CPU as possible is vital to the computers speed - RAM is a type of microprocessor chip - RAM is temporary and most cases volatile, RAM chips lose their contents if the current is lost or turned off as in a power surge, burnout, or electrical noise generated by lighting or nearby machines - RAM chips are located directly on the mother board or in other chips located on peripheral cards that plug into the main circuit board - two main types of RAM are dynamic RAM (DRAM) and static RAM (SRAM) - DRAM memory chips offer the greatest capacities and the lowest cost per bit, but they are relatively slow - SRAM costs more than DRAM but it is faster - for this reason, SRAM is the preferred choice for performance sensitive applications - emerging technology is magnetic RAM (MRAM) which uses magnetism rather than electricity to store data - another advantage is that MRAM is non volatile - DRAM wastes lots of electricity since needs to be supplied with constant current to store data where as MRAM requires only a tiny amount of electricity - MRAM combines high speed of SRAM the storage capacity of DRAM and the non volatility of flash memory 3. Cache Memory - type of high speed memory enables the computer to temporarily store blocks of data that are used more often and that a processor can access more rapidly than main memory (RAM) - many modern computer applications (Microsoft vista example) are complex and have huge numbers of instructions therefore takes a lot of RAM capacity to store the entire instruction set - also many applications might exceed your RAM but in either case, the processor must go to secondary storage to retrive the necessary instructions - to alleviate this problem, software is often written in smaller blocks of instructions - as these blocks are needed they can be brought from secondary storage into RAM - this process is still slower, however. - cache memory is a place closer to the CPU than RAM where the computer can temporarily store those blocks of instructions that are used more often - blocks used less often remain in RAM until they are transferred to cache, blocks used infrequently remain in secondary storage - cache memory is faster than RAM because the instructions travel a shorter distance to the CPU 4. Read Only Memory: - when lose data, usually lose from RAM, cache or the registers at the time because these types of memory are volatile - Read only memory (ROM) is the place – type of chip – where certain critical instructions are safeguarded - ROM is non volatile so it retinas these instructions when the power to the computer is turned off - read only designation means that these instructions can only be read by the computer and can not be changed by the user - example of ROM is the instructions needed to start or boot the computer after it has been shut off Secondary Storage - designed to store very large amounts of data for extended periods of time - can have memory capacity of several terabytes or more Characteristics - it is non volatile - takes more time to retrieve data from secondary storage than it does from RAM - cheaper than primary storage - can take place on a variety of media, each with its own technology - overall trends in secondary storage are toward more direct access methods, higher capacity with lower costs and increased portability *Good diagram on page 340 outlines primary memory compared with secondary storage as to the cost, size, and speed (which one is better)* 1. Magnetic Media - magnetic storage uses patterns of magnetization to store information in a non volatile way on tape or disks - Magnetic Tape: kept on a large open real or in smaller cartridge or cassette - old technology, still remains popular since it is the cheapest storage medium and can handle enormous amounts of data - but it is the slowest method of retrieving data since all the data is placed on the tape sequentially - Sequential Access: means that the system might have to run through the majority of the tape before it comes to the desired place of data - magnetic tape storage, often used for information that an organization must maintain but uses only rarely or does not need immediate access to - industries with huge numbers of files for instance, insurance companies, use magnetic tape systems - modern versions of these systems use cartridges and often a robotic system that selects and loads the appropriate cartridge automatically - also tape systems like digital audio tapes (DAT) for smaller applications such as storing copies of all the contents of a personal computers secondary storage (‘backing up’ the storage) - Magnetic Disk: form of secondary storage on a magnetized disk that is divided into tracks and sectors that provide addresses for various pieces of data - allow much more rapid access to data than the magnetic tape - these are also called hard drives or fixed disk drives, and most commonly used mass storage devices because of their low cost, high speed, and large storage capacity - hard disk drives read from, and write to, stacks of rotating (at up to 15000, RPM) magnetic disk platters mounted in rigid enclosures, and sealed against environmental and atmospheric contamination - these disks are permanently mounted in a unit that may be internal or external to the computer - Hard drives store data on platters that are divided into concentric tracks. - Each track is further divided into segments called sectors. - To access a given sector, a read/write head pivots across the rotating disks to locate the right track, which is calculated from an index table. - The head then waits as the disk rotates until the right sector is underneath it - Because the head floats just above the surface of the disk (less than 25 microns), any bit of dust or contamination can disrupt the device. - When this happens, it is called a disk crash,and it usually results in catastrophic loss of data. For this reason, hard drives are hermetically sealed when they are manufactured - Every piece of data has an address attached to it, corresponding to a particular track and sec tor. Any piece of desired data can be retrieved in a nonsequential manner, by direct access. - This is why hard disk drives are sometimes called direct access storage devices. - The read/write heads use the data's address to quickly find and read the data (see Figure TG1.5). - Unlike magnetic tape, the system does not have to read through all the data to find what it wants. - Modern personal computers typically have internal hard drives with storage capacity rang ing from hundreds of gigabytes to several terabytes. - Data access is very fast, measured in mil liseconds, though still much slower than RAM. - Because they are somewhat susceptible to mechanical failure, and because users may need to take all of their hard drive's contents to another location, many users back up their hard drives contents with either a portable hard disk drive system or thumb drives - most PC’s and workstations use one of two high performance disk interface standards: Enhances Integrated Drive Electronics (EIDE) or Small Computer Systems Interface (SCSI) - EIDE offers good performance, inexpensive and supports upto four disks, tapes, CD – ROM drives - SCSI drives are more expensive than EIDE drives, but they offer a faster interface and support more devices - SCSI interfaces are therefore used for graphics workstations, server based storage and large databases 2. Optical Storage Devices - do not store data via magnetism - a laser reads the surface of a reflective plastic platter - optical disk drives are slower than magnetic hard drives but they are les ussceptile to damage from contamination and are less fragile - optical disks can store a great deal of information, both on a routine basis and when combined into storage systems - optical disk storage systems are often implemented in the form of optical jukeboxes, which store many disks and operate much like the automated phonograph record changes for which they are named - types of optical disks include compact disks read only memory (CD-ROM) and digital video disk (DVD) 3. Compact disk, Read Only Memory: CD ROM storage devices feature high capacity, low cost, and high durability - since CD ROM is a read only medium, it cannot be written on - compact disk, rewritable (CD-RW) storage devices are recordable and rewritable 4. Digital Video Disk: DVD is a five inch disk with the capacity to store about 135 minutes of digital video - provides, sharp detail, true color, no flicker and no snow - also perform as computer storage disks, providing storage capabilities of 17 gigabytes - can read current CD ROMs but current CD ROM players can not read DVDs - access speed of a DVD drive is faster than that of a typical CD ROM drive 5. Holographic Memory: an optical technology that uses a three dimensional medium to store data - InPhase Tehcnologies Inc has produced a write once, read many (WORM) optical disk that stores 300 gigabytes - each disk has 63 times the capacity of a DVD and can store more than 35 hours of broadcast quality video 6. Flash Memory Devices: Flash memory is non-volatile computer memory that can be electrically erased and reprogrammed. - This technology can be built into a system or installed on a personal computer card. - Flash memory devices (or memory cards) are electronic storage devices that contain no moving parts and use 30 times less battery power than hard drives. - more smaller and durable than hard drives - flash devices store less data than hard drives and are more expensive - flash devices are used with digital cameras, handheld and laptop computers, tele phones, music players, and video game consoles - Apple (www.apple.com/car)eplaced the micro hard-drive-based iPod Mini with the flash-based iPod Nano for four reasons: (1) rapid improvements in the storage capacity of flash memory chips, (2) rapid decreases in cost, (3) much longer battery life, and (4) smaller size - One popular flash memory device is the thumb drive (also called memorystick, jump drive,or flashdrive) - These devices fit into Universal Serial Bus (USB) ports on personal computers and other devices and they can store many gigabytes. Thumb drives have replaced magnetic floppy disks for portable storage Enterprise Storage Syste
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