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  • Literature in programming and computer science

    - by Peter Turner
    I hope, gentle programmers, that you'll forgive me for not asking a "Soft Question" on theoreticalCS.SE and asking this here. It has recently come to my attention that bigendian came from Jonathan Swift's Gulliver's Travels. I was pretty surprised when listening to the book on my commute to hear something I'd only heard before in Comp Sci / Engineering classes. I thought it was some sort of nouveau-politically incorrect piece of holdover jargon like Master and Slave drives or Polish Notation. Are there any other incidents, not of politically incorrect jargon, but of literature influencing aspects of computers, programming or software development?

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  • Computer Networks UNISA - Chap 15 &ndash; Network Management

    - by MarkPearl
    After reading this section you should be able to Understand network management and the importance of documentation, baseline measurements, policies, and regulations to assess and maintain a network’s health. Manage a network’s performance using SNMP-based network management software, system and event logs, and traffic-shaping techniques Identify the reasons for and elements of an asset managements system Plan and follow regular hardware and software maintenance routines Fundamentals of Network Management Network management refers to the assessment, monitoring, and maintenance of all aspects of a network including checking for hardware faults, ensuring high QoS, maintaining records of network assets, etc. Scope of network management differs depending on the size and requirements of the network. All sub topics of network management share the goals of enhancing the efficiency and performance while preventing costly downtime or loss. Documentation The way documentation is stored may vary, but to adequately manage a network one should at least record the following… Physical topology (types of LAN and WAN topologies – ring, star, hybrid) Access method (does it use Ethernet 802.3, token ring, etc.) Protocols Devices (Switches, routers, etc) Operating Systems Applications Configurations (What version of operating system and config files for serve / client software) Baseline Measurements A baseline is a report of the network’s current state of operation. Baseline measurements might include the utilization rate for your network backbone, number of users logged on per day, etc. Baseline measurements allow you to compare future performance increases or decreases caused by network changes or events with past network performance. Obtaining baseline measurements is the only way to know for certain whether a pattern of usage has changed, or whether a network upgrade has made a difference. There are various tools available for measuring baseline performance on a network. Policies, Procedures, and Regulations Following rules helps limit chaos, confusion, and possibly downtime. The following policies and procedures and regulations make for sound network management. Media installations and management (includes designing physical layout of cable, etc.) Network addressing policies (includes choosing and applying a an addressing scheme) Resource sharing and naming conventions (includes rules for logon ID’s) Security related policies Troubleshooting procedures Backup and disaster recovery procedures In addition to internal policies, a network manager must consider external regulatory rules. Fault and Performance Management After documenting every aspect of your network and following policies and best practices, you are ready to asses you networks status on an on going basis. This process includes both performance management and fault management. Network Management Software To accomplish both fault and performance management, organizations often use enterprise-wide network management software. There various software packages that do this, each collect data from multiple networked devices at regular intervals, in a process called polling. Each managed device runs a network management agent. So as not to affect the performance of a device while collecting information, agents do not demand significant processing resources. The definition of a managed devices and their data are collected in a MIB (Management Information Base). Agents communicate information about managed devices via any of several application layer protocols. On modern networks most agents use SNMP which is part of the TCP/IP suite and typically runs over UDP on port 161. Because of the flexibility and sophisticated network management applications are a challenge to configure and fine-tune. One needs to be careful to only collect relevant information and not cause performance issues (i.e. pinging a device every 5 seconds can be a problem with thousands of devices). MRTG (Multi Router Traffic Grapher) is a simple command line utility that uses SNMP to poll devices and collects data in a log file. MRTG can be used with Windows, UNIX and Linux. System and Event Logs Virtually every condition recognized by an operating system can be recorded. This is typically done using event logs. In Windows there is a GUI event log viewer. Similar information is recorded in UNIX and Linux in a system log. Much of the information collected in event logs and syslog files does not point to a problem, even if it is marked with a warning so it is important to filter your logs appropriately to reduce the noise. Traffic Shaping When a network must handle high volumes of network traffic, users benefit from performance management technique called traffic shaping. Traffic shaping involves manipulating certain characteristics of packets, data streams, or connections to manage the type and amount of traffic traversing a network or interface at any moment. Its goals are to assure timely delivery of the most important traffic while offering the best possible performance for all users. Several types of traffic prioritization exist including prioritizing traffic according to any of the following characteristics… Protocol IP address User group DiffServr VLAN tag in a Data Link layer frame Service or application Caching In addition to traffic shaping, a network or host might use caching to improve performance. Caching is the local storage of frequently needed files that would otherwise be obtained from an external source. By keeping files close to the requester, caching allows the user to access those files quickly. The most common type of caching is Web caching, in which Web pages are stored locally. To an ISP, caching is much more than just convenience. It prevents a significant volume of WAN traffic, thus improving performance and saving money. Asset Management Another key component in managing networks is identifying and tracking its hardware. This is called asset management. The first step to asset management is to take an inventory of each node on the network. You will also want to keep records of every piece of software purchased by your organization. Asset management simplifies maintaining and upgrading the network chiefly because you know what the system includes. In addition, asset management provides network administrators with information about the costs and benefits of certain types of hardware or software. Change Management Networks are always in a stage of flux with various aspects including… Software changes and patches Client Upgrades Shared Application Upgrades NOS Upgrades Hardware and Physical Plant Changes Cabling Upgrades Backbone Upgrades For a detailed explanation on each of these read the textbook (Page 750 – 761)

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  • What You Said: How You Customize Your Computer

    - by Jason Fitzpatrick
    Earlier this week we asked you to share the ways you customize your computing experience. You sounded off in the comments and we rounded up your tips and tricks to share. Read on to see how your fellow personalize their computers. It would seem the first stop on just about everyone’s customization route is stripping away the bloat/crapware. Lisa Wang writes: Depending on how much time I have when I receive my new machine,I might do the following in a few batches, starting with the simplest one. Usually, my list goes like this:1.Remove all bloatware and pretty much unneeded stuffs.2.Change my wallpaper,login screen,themes, and sound.3.Installing my ‘must-have’ softwares-starting with fences and rocketdock+stacks plugin4.Setting taskbar to autohide, pinning some apps there5.Installing additional languages6.Tweaking all settings and keyboard shortcuts to my preferance7.Changing the icons(either manual or with TuneUp Styler) Interface tweaks like the aforementioned Fences and Rocket Dock made quite a few appearances, as did Rainmeter. Graphalfkor writes: How to Stress Test the Hard Drives in Your PC or Server How To Customize Your Android Lock Screen with WidgetLocker The Best Free Portable Apps for Your Flash Drive Toolkit

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  • Illumination and Shading for computer graphics class

    - by Sam I Am
    I am preparing for my test tomorrow and this is one of the practice questions. I solved it partially but I am confused with the rest. Here is the problem: Consider a gray world with no ambient and specular lighting ( only diffuse lighting). The screen coordinates of a triangle P1,P2,P3, are P1=(100,100), P2= (300,150), P3 = (200, 200). The gray values at P!,P2,P3 are 1/2, 3/4, and 1/4 respectively. The light is at infinity and its direction and gray color are (1,1,1) and 1.0 respectively. The coefficients of diffused reflection is 1/2. The normals of P1,P2,P3 are N1= (0,0,1), N2 = (1,0,0), and N3 = (0,1,0) respectively. Consider the coordinates of three points P1,P2,P3 to be 0. Do not normalize the normals. I have computed that the illumination at the 3 vertices P1,P2,P3 is (1/4,3/8,1/8). Also I computed that interpolation coefficients of a point P inside the triangle whose coordinates are (220, 160) are given by (1/5,2/5,2/5). Now I have 4 more questions regarding this problem. 1) The illumination at P using Gouraud Shading is: i) 1/2 The answer is 1/2, but I have no idea how to compute it.. 2) The interpolated normal at P is given by i) (2/5, 2/5,1/5) ii) (1/2, 1/4, 1/4) iii) (3/5, 1/5, 1/5) 3) The interpolated color at P is given by: i) 1/2 Again, I know the correct answer but no idea how to solve it 4) The illumination at P using Phong Shading is i) 1/4 ii) 9/40 iii) 1/2

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  • Determinism in multiplayer simulation with Box2D, and single computer

    - by Jake
    I wrote a small test car driving multiplayer game with Box2D using TCP server-client communcations. I ran 1 instance of server.exe and 2 instance of client.exe on the same machine that I code and compile the executables. I type inputs (WASD for a simple car movement) into one of the 2 clients and I can get both clients to update the simulation. There are 2 cars in the simulation. As long as the cars do not collide, I get the same identical output on both client.exe. I can run the car(s) around for as long as I could they still update the same. However, if I start to collide the cars, very quickly they go out of sync. My tools: Windows 7, C++, MSVS 2010, Box2D, freeGlut. My Psuedocode: // client.exe void timer(int value) { tcpServer.send(my_inputs); foreach(i = player including myself) inputs[i] = tcpServer.receive(); foreach(i = player including myself) players[i].process(inputs[i]); myb2World.step(33, 8, 6); // Box2D world step simulation foreach(i = player including myself) renderer.render(player[i]); glutTimerFunc(33, timer, 0); } // server.exe void serviceloop { while(all clients alive) { foreach(c = clients) tcpClients[c].receive(&inputs[c]); // send input of each client to all clients foreach(source = clients) { foreach(dest = clients) { tcpClients[dest].send(inputs[source]); } } } } I have read all over the internet and SE the following claims (paraphrased): Box2D is deterministic as long as floating point architecture/implementation is the same. (For any deterministic engine) Determinism is gauranteed if playback of recorded inputs is on the same machine with exe compiled using same compiler and machine. Additionally my server.exe and client.exe gameloop is single thread with blocking socket calls and fixed time step. Question: Can anyone explain what I did wrong to get different Box2D output?

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  • My computer will no longer suspend or shut off when I close the lid

    - by dave
    This is somewhat annoying. I have an old laptop and the screen on it is shot, so now I have an old monitor hooked up and it works fine. Before the upgrade I had it set so that when i closed the lid on the laptop everything would shutdown or suspend, when I lift the lid, everything would come back. Now, however, when i close the lid nothing happens, when i open the lid the screen flashes black and comes back. I have it set so that it should suspend when i close the lid. It's confusing...

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  • come on!teach u save photos from iphone to computer

    - by goodm
    i am using iphone ,when we have fun,we took a lot of nice pics ,but,that is a question,how to transfer photos from iphone to computer,now ,let me show you,step by step: Step 1: Download Tansee iPhone Transfer Photo free trial version here,and then install it. You also need iTunes above 7.3 installed.or download at: http://www.softseeking.com/prodail.aspx?proid=74 Step 2: Connect iPhone to your computer. Step 3: Launch Tansee iPhone Transfer Photo and all the photos in your iPhone will display automatically, Step 4: Select the photos to be transferred to your computer, the selected file will marked with red border. You can select photos by click on each one, or just drag a rectangle to select a bundle of photos. You can also select all photos by click right button of your mouse or click "File" to choose. Note: you can only select first 6 photos if you haven't purchase. Step 5: Click "Copy" button to select output path and start to transfer photos to your computer: iPhone Camera Photo & Camera Video: Click "Camera Roll", do as steps above can copy your iPhone Camera Photos and iPhone Camera Videos to PC. Options Setting 1.Backup File Format: To select backup photo file format, Tansee iPhone Transfer Photo support BMP and JPG file now. 2.Backup Path: To select directory for storing the backup photos. You can select backup directory for each photo during backup by check "Ask Every Time" or store all files in a specified directory by checking "Save Here" and select the directory in the edit box. 3.Backup Resolution: To select the photo size to be backup.

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  • Computer Networks UNISA - Chap 8 &ndash; Wireless Networking

    - by MarkPearl
    After reading this section you should be able to Explain how nodes exchange wireless signals Identify potential obstacles to successful transmission and their repercussions, such as interference and reflection Understand WLAN architecture Specify the characteristics of popular WLAN transmission methods including 802.11 a/b/g/n Install and configure wireless access points and their clients Describe wireless MAN and WAN technologies, including 802.16 and satellite communications The Wireless Spectrum All wireless signals are carried through the air by electromagnetic waves. The wireless spectrum is a continuum of the electromagnetic waves used for data and voice communication. The wireless spectrum falls between 9KHZ and 300 GHZ. Characteristics of Wireless Transmission Antennas Each type of wireless service requires an antenna specifically designed for that service. The service’s specification determine the antenna’s power output, frequency, and radiation pattern. A directional antenna issues wireless signals along a single direction. An omnidirectional antenna issues and receives wireless signals with equal strength and clarity in all directions The geographical area that an antenna or wireless system can reach is known as its range Signal Propagation LOS (line of sight) uses the least amount of energy and results in the reception of the clearest possible signal. When there is an obstacle in the way, the signal may… pass through the object or be obsrobed by the object or may be subject to reflection, diffraction or scattering. Reflection – waves encounter an object and bounces off it. Diffraction – signal splits into secondary waves when it encounters an obstruction Scattering – is the diffusion or the reflection in multiple different directions of a signal Signal Degradation Fading occurs as a signal hits various objects. Because of fading, the strength of the signal that reaches the receiver is lower than the transmitted signal strength. The further a signal moves from its source, the weaker it gets (this is called attenuation) Signals are also affected by noise – the electromagnetic interference) Interference can distort and weaken a wireless signal in the same way that noise distorts and weakens a wired signal. Frequency Ranges Older wireless devices used the 2.4 GHZ band to send and receive signals. This had 11 communication channels that are unlicensed. Newer wireless devices can also use the 5 GHZ band which has 24 unlicensed bands Narrowband, Broadband, and Spread Spectrum Signals Narrowband – a transmitter concentrates the signal energy at a single frequency or in a very small range of frequencies Broadband – uses a relatively wide band of the wireless spectrum and offers higher throughputs than narrowband technologies The use of multiple frequencies to transmit a signal is known as spread-spectrum technology. In other words a signal never stays continuously within one frequency range during its transmission. One specific implementation of spread spectrum is FHSS (frequency hoping spread spectrum). Another type is known as DSS (direct sequence spread spectrum) Fixed vs. Mobile Each type of wireless communication falls into one of two categories Fixed – the location of the transmitted and receiver do not move (results in energy saved because weaker signal strength is possible with directional antennas) Mobile – the location can change WLAN (Wireless LAN) Architecture There are two main types of arrangements Adhoc – data is sent directly between devices – good for small local devices Infrastructure mode – a wireless access point is placed centrally, that all devices connect with 802.11 WLANs The most popular wireless standards used on contemporary LANs are those developed by IEEE’s 802.11 committee. Over the years several distinct standards related to wireless networking have been released. Four of the best known standards are also referred to as Wi-Fi. They are…. 802.11b 802.11a 802.11g 802.11n These four standards share many characteristics. i.e. All 4 use half duplex signalling Follow the same access method Access Method 802.11 standards specify the use of CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) to access a shared medium. Using CSMA/CA before a station begins to send data on an 802.11 network, it checks for existing wireless transmissions. If the source node detects no transmission activity on the network, it waits a brief period of time and then sends its transmission. If the source does detect activity, it waits a brief period of time before checking again. The destination node receives the transmission and, after verifying its accuracy, issues an acknowledgement (ACT) packet to the source. If the source receives the ACK it assumes the transmission was successful, – if it does not receive an ACK it assumes the transmission failed and sends it again. Association Two types of scanning… Active – station transmits a special frame, known as a prove, on all available channels within its frequency range. When an access point finds the probe frame, it issues a probe response. Passive – wireless station listens on all channels within its frequency range for a special signal, known as a beacon frame, issued from an access point – the beacon frame contains information necessary to connect to the point. Re-association occurs when a mobile user moves out of one access point’s range and into the range of another. Frames Read page 378 – 381 about frames and specific 802.11 protocols Bluetooth Networks Sony Ericson originally invented the Bluetooth technology in the early 1990s. In 1998 other manufacturers joined Ericsson in the Special Interest Group (SIG) whose aim was to refine and standardize the technology. Bluetooth was designed to be used on small networks composed of personal communications devices. It has become popular wireless technology for communicating among cellular telephones, phone headsets, etc. Wireless WANs and Internet Access Refer to pages 396 – 402 of the textbook for details.

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  • What Is Spyware And How Does It Affect Your Computer

    Spyware is a type of malware (i.e., malicious software) that is installed on computers without the user';s consent. Spyware goes about collecting small amounts of information at a time about you. What... [Author: Daniel T. Driver - Computers and Internet - May 08, 2010]

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  • A Computer Novice Can Build A Website

    Well, you know how things have been lately, economic downturn, credit crunch - call it what you like, but work has been slow, so, I decided that what I really needed to do was get a website designed,... [Author: Barney Yarnell - Web Design and Development - June 18, 2010]

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  • Get Rid off Computer Virus

    When you hear those words like love bug, back orifice, Trojan horses, and the Davinci virus, you get the shock of your life especially when you see them on your PC. All these are greatly hyped Antivi... [Author: Sarah N Jones - Computers and Internet - April 21, 2010]

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  • bought computer with ubuntu program messed up

    - by linda stecker
    i recently got a dell inspiron B130 with an ubuntu prgm on it and the main users desktop is scattered allover the place , files everywhere but not in folders,how do i fix this? i am new working with this operating system ,used to windows versions. if i go into a guest profile the desktop is perfectly fine and everything works but i cannot make the system fix itself or don't really know where to start help??????? i have the user name and password and can get to terminal screen , but not sure how to remove and add myself to admin use

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  • To same computer Remote desktop thrue WRT54G router

    - by Kangarooo
    Cant access from my Same comp same comp to test if all is ok. Tryd all mentioned posibilities. Tryd my ip xxx.xxx.xxx.xxx / localhost with / without :5900 added with / without in "Remote desktop" checked "Configure network automatically to accept connection" with / without in router WRT54G enabled port 5900 forwardet to my comp 192.168.1.3 UPNP is enabled. I can connect to one other comp witch isnt using router and checked "Configure network automatically to accept connection" and to one thrue TENDA W311R+ router where ive put port forwarding to 5900 and there works xxx.xxx.xxx.xxx:5900 Whats wrong? What ive missed?

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  • how Computer Networks is related to Web/Desktop Java programming

    - by C4CodeE4Exe
    Being a Java programmer , I am wondering how could my work experience would help me learning networking skills. I know C language is used in network socket programming. I know if one knows how to program in one language its not tough to learn another language. Question is I am not able to find much on networks when it comes to Java(may be my knowledge is limited). Do companies like CISCO,TELUS Inc. rely heavily on programmers with such background.

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  • Looking for old version of JBuilder

    - by mtgrares
    I'm looking for any of these versions:JBuilder 3-9. The reason for this is because my computer is old (256 MB, 800 Mhz cpu) but I still like to program. (Yes, I should upgrade my computer but greenbacks don't grow on trees.) And to prove that I really do program, I have an open source project where you play the trading card game Magic: The Gathering against the computer, http://code.google.com/p/cardforge The latest version was downloaded 1,862 times.

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  • New computer - AMD with which mobo? [closed]

    - by RhZ
    I need to buy new computers for the office, all running ubuntu 10.04 or 11.10, whichever works. I am looking at a asus mobo with the AMD870 northbridge and 850 sounthbridge. Can anyone tell me if that is buggy or not? And with maybe an Athlon II X4 640 processor. At home I am running an asus mobo with AMD880/SB850 at home, which is good, although the on board ATI video card was buggy, I put a nvida card in as well and its great now. But for the office I want to save cost, don't need a kick-ill system. Still, I need the machines to be fast and look good, don't want to skimp on performance. Can anyone provide me with some advice about this? I will buy a custom machine, not from one of the big manufacturers. Thanks! :-)

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  • I cannot see the drives on my computer

    - by Joseph
    I'm a new Ubuntu user and I installed this Ubuntu 12.04 fromn a usb stick. It all went fine(I think) but as I notice, there are no drives shown on the menu. I tried some command in the terminal to see if the drives are available and yes, they are available. My problem is how to make these drives show up on the menu above. Sorry if this question is somewhat vague. (I removed the image because I am not allowed to add an image because I have insufficient reputation)

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  • bought computer with messed up Ubuntu

    - by linda stecker
    I recently got a dell inspiron B130 with an Ubuntu OS and the main users desktop is scattered allover the place , files everywhere but not in folders,how do i fix this? I am new working with this operating system ,used to windows versions. if i go into a guest profile the desktop is perfectly fine and everything works but i cannot make the system fix itself or dont really know where to start help???????

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  • tunneling x11vnc through ssh on a non standard port to ubuntu computer tightvnc

    - by user72372
    I have been stuck with setting up my virtual desktop on my ubuntu laptop. I am running ubuntu to ubuntu with x11vnc I start the process on my laptop as follows: " ssh -L5904:localhost:5900 -p Port remoteuser@remoteip." That command works, then I start x11vnc server, "x11vnc -noncache -once -shared -rfbauth ~/.vnc/passwd." This command works and starts connection. Then I open another window on my laptop and type, export VNC_VIA_CMD='/usr/bin/ssh -2 -c aes128-cbc -x -p Port -l User -f -: %L:%H:%R %G sleep 20' (not sure if works). then I type, vncviewer -endcodings Tight -depth 8 -quality 1 -via IPofremotemachine -u remoteuser localhost:01. The first time it work but from now on it just gives me the vncviewer -help screen everytime. I type in the password for my remote machine and then shows -help screen for vncviewer. I think the problem is with Tightvnc viewer but don't know what. Please help. I got some info on www.vanemery.com/Linux/VNC/vnc-over-ssh.html?.

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