Computer Science Engineering Assignment Writing Essay Help Question
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Prepare an essay for Computing Machine Cycle and its operations??
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The CPU of a computer continuously performs a series of steps at the rate of millions per second from the point the computer is started till it is shut down. This series of steps is the basic operation of a CPU and is called a machine cycle or a processor cycle.(Miller,R 2003. p. 53-54) This machine cycle comprises of four steps:-
- Fetch- In this step, data or command called operation code or opcode is fetched from a location in the main memory as directed by the program counter of the control unit and stored in the Instruction Register (IR) for future use. Register is a memory built in the CPU for quick access to frequently used information. The program counter is then incremented to point to the next instruction after the one just fetched.
- Decode- The opcode which is machine language instruction fetched from main memory is broken down into instruction sets by the control unit in this step and sent to the Arithmetic Logic Unit (ALU). Basically the machine language is decoded into binary code which an arithmetic logic unit and understand and work upon.
· Storing- The result of the execution is stored in the memory or in a register for future
use. If the information is used frequently, it might be stored on the CPU registers but the information is large, it is transferred to the main memory. No actual processing happens in this step.
A machine cycle can be divided into 2 parts, instruction cycle and execute cycle. The first two steps, fetch and decode make for an instruction time or I-time and the next two steps, execute and store make an execution time or E-time. I-time .and E-time together makes a machine cycle. All processors deploy the same machine cycle with some variations but the basic steps remain the same. The speed and performance of the computer or a CPU is measured in terms of instructions it can process in a second. Hertz (Megahertz or gigahertz) is the unit that measures number of machine cycles per second. In 8085 machine, nanoseconds and microseconds are used to measure machine cycles. One million cycles per second make 1 MHz. Typically a CPU can have 1.6 GHz to 3.6GHz speed. However, there are other factors such as memory and connected hardware which determine the performance of the computer.
Whenever an instruction is punched into the computer through any of the input device, it is the CPU or the processor which performs the fundamental operation of executing these instructions and giving the desired output. All instructions are broken down to small instructions and processors prioritize and execute them. Based on the OS and hardware, multiprocessing or parallel processing can be used to execute complex instructions in shortest possible span of time.
Multiprocessing, generally refers to the dynamic assignment of parts of the same task to multiple processors in the same computer to increase speed of execution. All the processors work simultaneously on the same program using the same memory of the system. Unix is the most commonly used multiprocessing systems. The basic platform for multiprocessing allows different computer to use the same program at the same time. Parallel processing employs many processors in the same computer or connected by a network for performing different tasks using a shared memory. Some supercomputers can have more than a couple of hundred processors all working at the same time. In parallel processing, number of calculations can be done at the same time thereby reducing the overall processing time. Parallel processing is effective in areas of weather forecasting, seismic science, advanced graphics and virtual reality. Single Instruction, Multiple Data (SIMD) and Multiple Instruction, Multiple Data (MIMD) programming models can use parallel processing technique. SIMD uses same set of instructions on different type of data while MIMD has independent processors which can give unique instructions for each data. Many SIMD processors can be clubbed together using grid technique to obtain a highly efficient super processor. While parallel processing removes dependency on one processor, it requires complex operating systems and large memory.
Multiprocessing can be divided as Symmetric multiprocessing (SMP) and Massively Parallel processing (MPP). SMP or tightly coupled multiprocessors share memory and I/O data path. Though SMP may involve more than one location, all the processors are controlled by a single OS. SMP usually does not have more than 16 processors. A typical example of SMP is wide networks in corporate where the data can be accessed from multiple locations using multiple processors from the same shared memory. In symmetrical multiprocessing, all the processors are equal in term of performing operations. Whereas in asymmetrical multiprocessing, processors work in a master slave configuration ie instruction is given to a main processor which delegates sub-instructions to other processors. The complete operation is controlled and coordinated by the main processor. Massively parallel processing uses several dozen processors which have their individual operating system and memory and are connected to each other via high speed communication system.
Thread basically is a set of instruction to be performed on any data that can execute independently of other programs. Multi-threading refers to multiprocessing of instructions from the same program using more than one processor. Hyper-threading technology developed by Intel Corp. (Intel Corp, 2008) and launched in February 2002 has significantly improved the performance of its Pentium 4 and Xeon processors. HT technolgy uses concurrency i.e. simultaneously executing multiple and structurally independent programs along with multithreading and latency. Hyper-threading or HT technology enables a single processor to execute two series, or threads, of instructions at the same time leading to a significant improvement in performance and system responsiveness. It allows the single processor to work as two logical processors and handle data instructions in parallel rather than one at a time. HT technology not only improves the overall system performance and reaction time but also enables increased number of users on a platform. Intel’s HT technology can be used on desktops, laptops, and workstation networks subject to the basic system requirements being met. The system needs HT enabled chipsets, system BIOS, HT enabled
Intel claims that performance of their Xeon Processor MP with HT technology has improved 30% on common server application benchmarks.(Intel Corp, 2008). Other strategic benefits of HT technology are as follows:
· Multiple users performing completely independent tasks on the same platform.
· Significant increase in the number of operations that can be performed simultaneously without comprising on speed and efficiency.
· Since the tasks are performed on independent threads, there is a considerable increase in throughput.
· Overall improvement in system performance and response time.
· Compatible with existing dual-processor and multi-processor systems.
Computer system uses data and information for processing from two types of locations viz. storage and memory. Memory is temporary storage of data and instructions while performing certain operations while storage refers to a more permanent location to store data. Memory usually erases when the system is shut down as compared to storage which is captured till further instruction to erase or modify the information. In terms of volatility, memory which is more volatile such as Random Access Memory (RAM) is termed as primary storage and non-volatile storage such as Read Only Memory (ROM) are called secondary storage. RAM is physically found on motherboards in the form chips. Typically, a RAM can have about 256 MB to 2GB of memory. However, there can be high end version with more storage capacity. Though this primary memory is easily accessible and hence improves speed manifold, it come with a drawback. The data stored in this memory will be erased when the computer is switched off. RAM is not only highly volatile but also very expensive in nature. Dynamic Random Access Memory (DRAM) is another type of RAM with stores information only for nanoseconds and needs to be refreshed regularly. RAM is measured in terms of megabytes, gigabytes and terabytes.Virtual memory is lesser expensive and only slightly slower to access than the RAM. When the data to be stored temporarily increases from the capacity of RAM, the OS uses some space on the hard disk called a paging space to store this data. RAM and virtual memory though are easily available; they are not as fast as the processors in modern computers. This can lead to a slowdown in the process. This hurdle is overcome by storing the data instantly required by the CPU in the CPU itself. Level 1 or primary cache memory stored in the CPU duplicates the most frequently used information from the main memory into itself for instant use by the CPU. The secondary or level 2 cache memory is stored in memory card near the CPU. Static Random Access Memory (SRAM) is used as cache memory. SRAM can be synchronous to match the speed of the CPU or it can be asynchronous. The dedicated circuit on the motherboard connects level 1 and level 2 cache memory to CPU, reducing the overall time in accessing data from the RAM or secondary storage devices. However, cache memory is very small in capacity; level 1 cache can be around 2 KB to 64 KB while level 2 cache can be somewhere between 256 KB to 2 MB. Registers is the type of memory that is frequently needed by the CPU or the arithmetic logic unit and is stored in the CPU itself. It is the most quickly accessible by the CPU but is very small in capacity and is measured in bits and kilobytes.
While RAM, virtual memory and cache memory are vital to the speed and performance of a system, they are very expensive, have small storage capacity and are extremely volatile. Large amounts and less frequently accessed of data is stored on alternate storage devices which are more permanent or non-volatile in nature. Read Only Memory (ROM), hard disks, CDs and DVDs are some examples of non-volatile memory.
In case of many users accessing the storage medium or storing large amounts of data on hard disks, the system becomes cumbersome and performance is affected. Remote storage is a convenient and cost-effective way of transferring the excess data to a removable storage devise or a devise not directly connected to your PC but connected via the network of the internet. Remote storage system monitors the space on the hard disk with respect to the defined attributes about volume and accessibility and automatically copies the files to alternate storage device when the threshold is reached. This frees up the space on local hard disk. The data is copied on to a library of magneto-optical tapes or hard drives on servers accessed through networks or internet. Remote storage has beneficial in more than one ways to organizations and individual requiring large storage spaces. These benefits are summarized below:
· Cost effective – Since data is stored on lesser expensive medium than hard disks, it results is cost reductions for organizations.
· Shared data- When the data is stored on network servers, it is accessible to all users and saves time and duplicity of storage by different users.
· Back up of data- Since data is copied on an additional resource, is is readily available in case of disaster.
· Increased storage space- For applications with little storage capacity such as mobiles, remote storage comes handy to store audio-visual files and large communication data.
On the basis of location of storing the data, remote storage is categorized as online storage or network storage.(Morley, Parker 2009. p 125)
Online storage- When the remote storage device is accessed via the internet, it is called at online storage. This type of storage is highly beneficial when large files such as digital pictures are to be shared through the internet. Online storage gives freedom of mobility to the user because the files can be accessed from anywhere via the internet. There are many sites which offer complementary online storage while there are sites which are dedicated to this purpose only. Such sites usually need a membership or charge some amount to store the data same as paying some rent to occupy a space. Online libraries, dictionaries, blogs etc are examples of functional uses of online remote storage.
Smart Cards are the next generation cards than the machine readable bar code or magnetic strip cards. Smart card is about the size of a credit card which has an embedded microchip in it with a processor, memory and storage. It stores data and performs operations on that data using the inbuilt processor. The data usually contains pre-entered information like an identity of an individual or an amount loaded in it which can be used for identification purposes. Data entered on the card can be processed and new information can be stored on it. Some high-end smart cards can also store biometric information like fingerprints in the microchip which enhance the security feature of the card manifold. Smart cards is a revolution in the field of data storage, transactions and security and are being accepted rapidly around the world for generic to more complex and specific purposes. Some of the significant features of smart card technology making it useful for varied applications are listed below:
Wireless communication and SIM cards – Subscriber Identity Modules (SIM) required for all mobile phones under Global System for Mobile communication (GSM) uses smart card technology exhaustively. The identity of the user, his preferences, activities and settings are stored in the SIM card. This technology has brought about a revolution in the telecommunications industry.·
Based on how the data is written and read from a card and the type of chip embedded in it, smart cards are classified as contact cards, contactless cards and multicomponent cards. The most common form of smart cards are contact cards in which the data is stored in a chip on the card and there are electric contacts located outside the card which connect to the card read or CAD( Card Accepting Device) when inserted in it. Contactless cards, also known as proximity cards use radio frequency to communicate between the card and the card reader without physically inserting the card. Vault cards or multicomponent cards employ a customized identification technique and are usually unique to a certain industry. Fingerprint indentifying smart cards are an example of vault cards.
The basic difference between a digital camera technology and a conventional film camera technology is that digital camera uses sensors which convert light into electrical charges instead of a chemical record. They depend on chemical and mechanical processes to capture images and reproduce images while digital cameras have built in computers in them and record images electronically. The images are converted into electrons using sensors made out of silicon. Sensors can be Charge Coupled Devices (CCD) or Complementary Metal Oxide Semiconductors (CMOS). CCDs and CMOS differ in terms of quality of image, speed, power usage, noise while processing and cost. The light falling on these sensors, which are made up of an array of pixels, is converted into electrons or an electrical signal. CCD sensors transfer individual pixel’s charge through a limited number of output nodes to convert to voltage, store it in buffer and then convert it to digital signal. Since every pixel’s charge is read independently, the quality of the image is superior. Such images are highly used in precision related applications such as scientific and industrial applications. However, CCD sensors use more power and are expensive to produce. CMOS has a circuitry to convert charge to voltage for every pixel by incorporating amplifiers and analog-to-digital converters in the chip itself. . Electric charges differ for intensity and brightness of light. Once the sensor captures the image, it passes through a color filter array which creates a color spectrum using basic colors red, blue and green. This electrical signal is converted to digital code using an analog to digital converter. This digital image is stored temporarily on a buffer memory and can be transferred to a more permanent storage device such as a memory card. The performance of the camera and quality of the image highly depends on resolution of the camera or the number of pixels. Each sensor is a grid of photo sites or picture elements “pixels” that absorb light and convert them into electrons. Higher the number of pixels on the sensors means more details of the image being captured resulting in better image quality.
Though the pixel captures every detail of the image, they cannot capture color and hence captures image in grayscales. Every sensor is has a color filter (such as a Bayer filter) placed over it which can allow the penetration of light in three basic colors i.e., red, blue and green. The camera then uses approximation to produce colors of the original image.
Digital cameras use four types of lenses depending on the magnitude and kind of zoom required: fixed-focus, fixed-zoom, optical zoom lenses with automatic focus and digital zoom lenses. The aperture i.e. the opening for light to pass through and shutter are used to control the amount of light reaching the sensors. Digital cameras use digital shutter instead of a mechanical shutter. Since digital cameras have extendable memory, they can store large number of images unlike conventional film cameras. Digital cameras use data compression to optimize storage and the images are stored in TIFF format or JPEG format.
Monochrome display was most commonly used in first generation of desktops till the 1970s. Monochrome monitors used CRT (cathode ray tube) technology to display a single color on a solid background, thus using only two colors to display text on the monitor such as green text on a black background.
Monochrome CRT use an electron gun in a vacuum tube to fire electrons on a phosphor coated screen which glows when stuck by the electrons. The electron gun is placed between intertwined coils which generate a magnetic field. This is used to deflect beams and thus control the intensity of the electron beam. Color CRT monitors employ three electron guns for each primary color red, blue and green which emit electron on the phosphor screen. The three guns are placed in a triangular shape or delta shape. The electrons hit the screen coated with phosphorous with different intensity to generate four basic colors. The electron beams pass through a metal plate called a shadow mask pierced with 3 holes. This leads the beams hit the phosphorous screen at an angle which and form a color dot pixel on the phosphorous screen. The screen is pattered in such a way that only a particular color beam can hit it after passing though the holes. The electron guns can also be aligned in a straight line called an aperture grill instead of a delta pattern for higher resolution CRTs.
· Storing- The result of the execution is stored in the memory or in a register for future
use. If the information is used frequently, it might be stored on the CPU registers but the information is large, it is transferred to the main memory. No actual processing happens in this step.
A machine cycle can be divided into 2 parts, instruction cycle and execute cycle. The first two steps, fetch and decode make for an instruction time or I-time and the next two steps, execute and store make an execution time or E-time. I-time .and E-time together makes a machine cycle. All processors deploy the same machine cycle with some variations but the basic steps remain the same. The speed and performance of the computer or a CPU is measured in terms of instructions it can process in a second. Hertz (Megahertz or gigahertz) is the unit that measures number of machine cycles per second. In 8085 machine, nanoseconds and microseconds are used to measure machine cycles. One million cycles per second make 1 MHz. Typically a CPU can have 1.6 GHz to 3.6GHz speed. However, there are other factors such as memory and connected hardware which determine the performance of the computer.
Whenever an instruction is punched into the computer through any of the input device, it is the CPU or the processor which performs the fundamental operation of executing these instructions and giving the desired output. All instructions are broken down to small instructions and processors prioritize and execute them. Based on the OS and hardware, multiprocessing or parallel processing can be used to execute complex instructions in shortest possible span of time.
Multiprocessing, generally refers to the dynamic assignment of parts of the same task to multiple processors in the same computer to increase speed of execution. All the processors work simultaneously on the same program using the same memory of the system. Unix is the most commonly used multiprocessing systems. The basic platform for multiprocessing allows different computer to use the same program at the same time. Parallel processing employs many processors in the same computer or connected by a network for performing different tasks using a shared memory. Some supercomputers can have more than a couple of hundred processors all working at the same time. In parallel processing, number of calculations can be done at the same time thereby reducing the overall processing time. Parallel processing is effective in areas of weather forecasting, seismic science, advanced graphics and virtual reality. Single Instruction, Multiple Data (SIMD) and Multiple Instruction, Multiple Data (MIMD) programming models can use parallel processing technique. SIMD uses same set of instructions on different type of data while MIMD has independent processors which can give unique instructions for each data. Many SIMD processors can be clubbed together using grid technique to obtain a highly efficient super processor. While parallel processing removes dependency on one processor, it requires complex operating systems and large memory.
Multiprocessing can be divided as Symmetric multiprocessing (SMP) and Massively Parallel processing (MPP). SMP or tightly coupled multiprocessors share memory and I/O data path. Though SMP may involve more than one location, all the processors are controlled by a single OS. SMP usually does not have more than 16 processors. A typical example of SMP is wide networks in corporate where the data can be accessed from multiple locations using multiple processors from the same shared memory. In symmetrical multiprocessing, all the processors are equal in term of performing operations. Whereas in asymmetrical multiprocessing, processors work in a master slave configuration ie instruction is given to a main processor which delegates sub-instructions to other processors. The complete operation is controlled and coordinated by the main processor. Massively parallel processing uses several dozen processors which have their individual operating system and memory and are connected to each other via high speed communication system.
Thread basically is a set of instruction to be performed on any data that can execute independently of other programs. Multi-threading refers to multiprocessing of instructions from the same program using more than one processor. Hyper-threading technology developed by Intel Corp. (Intel Corp, 2008) and launched in February 2002 has significantly improved the performance of its Pentium 4 and Xeon processors. HT technolgy uses concurrency i.e. simultaneously executing multiple and structurally independent programs along with multithreading and latency. Hyper-threading or HT technology enables a single processor to execute two series, or threads, of instructions at the same time leading to a significant improvement in performance and system responsiveness. It allows the single processor to work as two logical processors and handle data instructions in parallel rather than one at a time. HT technology not only improves the overall system performance and reaction time but also enables increased number of users on a platform. Intel’s HT technology can be used on desktops, laptops, and workstation networks subject to the basic system requirements being met. The system needs HT enabled chipsets, system BIOS, HT enabled
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