http://blog.bitcomet.com/10401613/en-usbitcomet.comFri, 03 Apr 2009 04:41:18 GMTFri, 03 Apr 2009 04:41:18 GMTbitcomet.comhttp://cyber.law.harvard.edu/rss/rss.html30http://blog.bitcomet.com/post/89087/MB3-215 as well as passive components, bonded tIntegrated circuits were made possible by experimental discoveries which showed that semiconductor devices could perform the functions of vacuum tubes, and by mid-20th-century technology advancements in semiconductor device fabrication. The integration of large numbers of tiny transistors into a small chip was an enormous improvement over the manual assembly of circuits using discrete electronic components.......]]>certkingFri, 03 Apr 2009 04:41:18 GMThttp://blog.bitcomet.com/post/89079/ While transferring data over the network, several data representations can be used. The two most common transfer modes are: 1. ASCII mode 2. Binary mode: In "Binary mode", the sending machine sends each file byte for byte and as such the recipient MB3-234 stores the bytestream as it receives it. (The FTP standard calls this "IMAGE" or "I" mode) In "ASCII mode", any form of data that is not plain text will be corrupted. When a file is sent using an ASCII-type transfer, the individual letters, numbers, and characters are sent using their ASCII character codes. The receiving machine saves these in a text file in the appropriate format (for example, a Unix machine saves it in a Unix format, a Windows machine saves it in a Windows format). Hence if an ASCII transfer is used it can be assumed plain text is sent, which is stored by the receiving computer in its own format. Translating between text formats might entail substituting the end of line and end......]]>certkingFri, 03 Apr 2009 03:49:58 GMThttp://blog.bitcomet.com/post/89078/ File Transfer Protocol (FTP) is a network protocol used to exchange and manipulate files over a TCP computer network, such as the internet. An FTP client may connect to an FTP server to manipulate files on that server.FTP runs over TCP.[1] It defaults to listen on port 21 for incoming connections from MB4-117 FTP clients. A connection to this port from the FTP Client forms the control stream on which commands are passed from the FTP client to the FTP server and on occasion from the FTP server to the FTP client. FTP uses out-of-band control, which means it uses a separate connection for control and data. Thus, for the actual file transfer to take place, a different connection is required which is called the data stream. Depending on the transfer mode, the process of setting up the data stream is different. Port 21 for control (or program), port 20 for data. In active mode, the FTP client opens a dynamic port, sends the FTP server the dynamic port number on which it is listening over the......]]>certkingFri, 03 Apr 2009 03:46:14 GMThttp://blog.bitcomet.com/post/89077/ Several new types of non-volatile RAM, which will preserve data while powered down, are under development. The technologies used include carbon nanotubes and the magnetic tunnel effect. In summer 2003, a 128 KB (128 × 210 bytes) magnetic RAM (MRAM) chip was manufactured with 0.18 µm technology. In June 2004,MB4-175 Infineon Technologies unveiled a 16 MB (16 × 220 bytes) prototype again based on 0.18 µm technology. Nantero built a functioning carbon nanotube memory prototype 10 GB (10 × 230 bytes) array in 2004. Whether some of these technologies will be able to eventually take a significant market share from either DRAM, SRAM, or flash-memory technology, however, remains to be seen. Since 2006, "Solid-state drives" (based on flash memory) with capacities exceeding 642 gigabytes and performance far exceeding traditional disks have become available. This development has started to blur the definition between traditional random access memory and "disks&......]]>certkingFri, 03 Apr 2009 03:45:02 GMThttp://blog.bitcomet.com/post/89075/ If a computer becomes low on RAM during intensive application cycles, many CPU architectures and operating systems are able to perform an operation known as "swapping". This makes use of a paging file, an area on aMB4-213 hard drive temporarily used as additional working memory. Constantly relying on this mechanism is called thrashing and is generally undesirable because it lowers overall system performance, mainly because hard drives are slower than RAM. Other uses of the "RAM" term Other physical devices with read–write capability can have "RAM" in their names: for example, DVD-RAM. "Random access" is also the name of an indexing method: hence, disk storage is often called "random access"[citation needed] because the reading head can move relatively quickly from one piece of data to another, and does not have to read all the data in between. However the final "M" is crucial: "RAM" (provided there is no additional......]]>certkingFri, 03 Apr 2009 03:43:58 GMThttp://blog.bitcomet.com/post/89074/ Random access memory (usually known by its acronym, RAM) is a form of computer data storage. Today it takes the form of integrated circuits that allows the stored data to be accessed in any order (i.e., at random). The word random thus refers to the fact that any piece of data can be returned in a constant MB4-219 time, regardless of its physical location and whether or not it is related to the previous piece of data.[1] This contrasts with storage mechanisms such as tapes, magnetic discs and optical discs, which rely on the physical movement of the recording medium or a reading head. In these devices, the movement takes longer than the data transfer, and the retrieval time varies depending on the physical location of the next item. The word RAM is mostly associated with volatile types of memory (such as DRAM memory modules), where the information is lost after the power is switched off. However, many other types of memory are RAM as well (i.e., Random Access Memory), including most types......]]>certkingFri, 03 Apr 2009 03:42:55 GMThttp://blog.bitcomet.com/post/89073/ One of the limitations of the original SMTP is that it has no facility for authentication of senders. Therefore the SMTP-AUTH extension was defined. However, the impracticalities of widespread SMTP-AUTH MB5-199 implementation and management means that E-mail spamming is not and cannot be addressed by it. Modifying SMTP extensively, or replacing it completely, is not believed to be practical, due to the network effects of the huge installed base of SMTP. Internet Mail 2000 was one such proposal for replacement. Spam is enabled by several factors, including vendors implementing broken MTAs (that do not adhere to standards, and therefore make it difficult for other MTAs to enforce standards), security vulnerabilities within the operating system (often exacerbated by always-on broadband connections) that allow spammers to remotely control end-user PCs and cause them to send spam, and a lack of "intelligence" in many MTAs. There are a number of proposals for sideband protocols that......]]>certkingFri, 03 Apr 2009 03:41:28 GMThttp://blog.bitcomet.com/post/89072/ An e-mail client requires the name or the IP address of an SMTP server as part of its configuration. The server will deliver messages on behalf of the user. This setting allows for various policies and network designs. End users connected to the Internet can use the services of an e-mail providerMB5-294 that is not necessarily the same as their connection provider (ISP). Network topology, or the location of a client within a network or outside of a network, is no longer a limiting factor for e-mail submission or delivery. Modern SMTP servers typically use a client's credentials (authentication) rather than a client's location (IP address), to determine whether it is eligible to relay e-mail. Server administrators choose whether clients use TCP port 25 (SMTP) or port 587 (Submission), as formalized in RFC 4409, for relaying outbound mail to a mail server. The specifications and many servers support both. Although some servers support port 465 for legacy secure SMTP in violation of the specificat......]]>certkingFri, 03 Apr 2009 03:40:35 GMThttp://blog.bitcomet.com/post/89071/ Simple Mail Transfer Protocol (SMTP) is an Internet standard for electronic mail (e-mail) transmission across Internet Protocol (IP) networks. SMTP was first defined in RFC 821 (STD 10), and last updated by RFC 5321 (2008), which describes the protocol in widespread use today, also known as extended SMTP MB6-283 (ESMTP). While electronic mail server software uses SMTP to send and receive mail messages, user-level client mail applications typically only use SMTP for sending messages to a mail server for relaying. For receiving messages, client applications usually use either the Post Office Protocol (POP) or the Internet Message Access Protocol (IMAP) to access their mail box accounts on a mail server.SMTP is a relatively simple, text-based protocol, in which one or more recipients of a message are specified (and in most cases verified to exist) along with the message text and possibly other encoded objects. The message is then transferred to a remote server using a series of queries and......]]>certkingFri, 03 Apr 2009 03:39:45 GMThttp://blog.bitcomet.com/post/89070/ Persistence in computer science refers to the characteristic of data that outlives the execution of the program that created it. Without this capability, data only exists in RAM, and will be lost when the memory loses power, such as on computer shutdown.In programming, persistence refers specifically to the abilityMB6-288 to retain data structures between program executions, such as, for example, an image editing program saving complex selections or a word processor saving undo history. This is achieved in practice by storing the data in non-volatile storage such as a file system or a relational database or an object database. Design patterns solving this problem are container based persistence, component based persistence and the Data Access Object model. When first introduced, the idea was that persistence should be an intrinsic property of the data, in contrast with the traditional approach where data is read and written to disk using imperative verbs in a programming language. This......]]>certkingFri, 03 Apr 2009 03:37:42 GMThttp://blog.bitcomet.com/post/89069/ In computing, a protocol is a convention or standard that controls or enables the connection, communication, and data transfer between computing endpoints. In its simplest form, a protocol can be defined as the rules governing the syntax, semantics, and synchronization of communication. Protocols may be implemented by hardware, software, or a combination of the two. At the lowest level, a MB7-221 protocol defines the behavior of a hardware connection.The widespread use and expansion of communications protocols is both a prerequisite for the Internet, and a major contributor to its power and success. The pair of Internet Protocol (or IP) and Transmission Control Protocol (or TCP) are the most important of these, and the term TCP/IP refers to a collection (or protocol suite) of its most used protocols. Most of the Internet's communication protocols are described in the RFC data of the Internet Engineering Task Force (or IETF). The protocols in human communication are separate rules about......]]>certkingFri, 03 Apr 2009 03:34:51 GMThttp://blog.bitcomet.com/post/89068/ A video card, also known as a graphics accelerator card, display adapter, or graphics card, is an expansion card whose function is to generate and output images to a display. Some video cards offer added functions, such as MB7-224 video capture, TV tuner adapter, MPEG-2 and MPEG-4 decoding, FireWire, light pen, TV output, or the ability to connect multiple monitors. A misconception regarding high end video cards is that they are strictly used for video games. High end video cards have a much broader range of capability; for example, they play a very important role for graphic designers and 3D animators, who tend to require optimum displays as well as faster rendering. Video cards are not used exclusively in IBM type PCs; they have been used in devices such as Commodore Amiga (connected by the slots Zorro II and Zorro III), Apple II, Apple Macintosh, Atari Mega ST/TT (attached to the MegaBus or VME interface), Spectravideo SVI-328, MSX, and in video game consoles. Video hardware can be......]]>certkingFri, 03 Apr 2009 03:33:14 GMThttp://blog.bitcomet.com/post/89067/ As of 2006[update], most efforts at scaling multicast up to large networks have concentrated on the simpler case of single-source multicast, which seems to be more computationally tractable. MB7-232 Still, the large state requirements in routers make applications using a large number of trees unworkable using IP Multicast. Take presence information as an example where each person needs to keep at least one tree of its subscribers if not several. No mechanism has yet been demonstrated that would allow the IP Multicast model to scale to millions of senders and millions of multicast groups and, thus, it is not yet possible to make fully-general multicast applications practical. For these reasons, and also reasons of economics, IP Multicast is not in general use in the commercial Internet. Explicit Multi-Unicast (XCAST) is an alternate multicast strategy to IP Multicast that provides reception addresses of all destinations with each packet. As such, since the IP packet size is limited in general,......]]>certkingFri, 03 Apr 2009 03:31:30 GMThttp://blog.bitcomet.com/post/89066/ Multicast addressing is a network technology for the delivery of information to a group of destinations simultaneously using the most efficient strategy to deliver the messages over each link of the network only once, creating copies only when the links to the multiple destinations split. The word "multicast" is typically used to refer to IP Multicast, which is often employed for streaming media and MB7-255 Internet television applications. In IP Multicast the implementation of the multicast concept occurs at the IP routing level, where routers create optimal distribution paths for datagrams sent to a multicast destination address spanning tree in real-time. At the Data Link Layer, Multicast is also used to describe one-to-many distribution such as Ethernet multicast addressing, Asynchronous Transfer Mode (ATM) point-to-multipoint virtual circuits or Infiniband multicast.IP Multicast is a technique for one to many communication over an IP infrastructure. It scales to a larger......]]>certkingFri, 03 Apr 2009 03:30:39 GMThttp://blog.bitcomet.com/post/89064/ In computer architecture, Shared Memory Architecture (SMA) refers to a design where the graphics chip does not have its own dedicated memory, and instead shares the main system RAM with the CPU and other components.MB3-412 This design is used with many integrated graphics solutions to reduce the cost and complexity of the motherboard design, as no additional memory chips are required on the board. There is usually some mechanism (via the BIOS or a jumper setting) to select the amount of system memory to use for graphics, which means that the graphics system can be tailored to only use as much RAM as is actually required, leaving the rest free for applications. A side-effect of this is that when some RAM is allocated for graphics, it becomes effectively unavailable for anything else, so an example computer with 512 MB RAM set up with 64MB graphics RAM will appear to the operating system and user to only have 448 MB RAM installed. The disadvantage of this design is lower performance because......]]>certkingFri, 03 Apr 2009 03:26:51 GMThttp://blog.bitcomet.com/post/89063/ In computing, shared memory is a memory that may be simultaneously accessed by multiple programs with an intent to provide communication among them or avoid redundant copies. Depending on context, programs may run on a single processor or on multiple separate processors. Using memory for communication inside a single MB4-349 program, for example among its multiple threads, is generally not referred to as shared memory.In hardware In computer hardware, shared memory refers to a (typically) large block of random access memory that can be accessed by several different central processing units (CPUs) in a multiple-processor computer system. A shared memory system is relatively easy to program since all processors share a single view of data and the communication between processors can be as fast as memory accesses to a same location. The issue with shared memory systems is that many CPUs need fast access to memory and will likely cache memory, which has two complications: * CPU-to-memory connection......]]>certkingFri, 03 Apr 2009 03:25:19 GMThttp://blog.bitcomet.com/post/89061/ Concurrent computing is a form of computing in which programs are designed as collections of interacting computational processes that may be executed in parallel.[1] Concurrent programs can be executed sequentially mb2-423 on a single processor by interleaving the execution steps of each computational process, or executed in parallel by assigning each computational process to one of a set of processors that may be in close proximity or distributed across a network. The main challenges in designing concurrent programs are ensuring the correct sequencing of the interactions or communications between different computational processes, and coordinating access to resources that are shared between processes.[1] A number of different methods can be used to implement concurrent programs, such as implementing each computational process as an operating system process, or implementing the computational processes as a set of threads within a single operating system process. Pioneers in the field of......]]>certkingFri, 03 Apr 2009 03:24:00 GMThttp://blog.bitcomet.com/post/89060/MB3-430 PLC-systems working in the longwave range are used. Emergency Remotely controlled machinery is used in radioactive or toxic environments to avoid human casualties and damage to human health. For example, remotely controlled robots were used during liquidation of circumstances of Chernobyl disaster.These are also used on Police vans, ambulances and firetrucks to change lights to green in that lane. Military Only in the military field of use of remote controls can you find the jammers and the countermeasures against the jammers. Jammers are used to disable or sabotage the enemy's use of remote controls. IED jamming systems, Radio jamming, Electronic warfare The distances for military remote controls also tend to be much longer, up to intercontinental distance satellite linked remote controls used by the U.S. for their unmanned airplanes (drones) in Afghanistan,......]]>certkingFri, 03 Apr 2009 03:22:35 GMThttp://blog.bitcomet.com/post/89058/MB5-554 was that it could “learn” remote signals from other different devices. It also had the ability to perform specific or multiple functions at various times with its built in clock. It was also the first remote control which could be linked to a computer and loaded with updated software code as needed. The CORE unit never made a huge impact of the market. It was much too cumbersome for the average user to program, but it received rave reviews from those who could figure out how to program it. These obstacles eventually lead to the demise of CL 9, but one of its employees continued the business under the name Celadon. This was one of the first computer controlled......]]>certkingFri, 03 Apr 2009 03:21:31 GMThttp://blog.bitcomet.com/post/89057/MB6-507 of "lazy" people for good.[5] The initial purpose to the TV remote was to turn off the TV set from afar, and to change the channels or mute commercials. People were told that the remote could turn off the TV while they were still laying in their LaZBoy and thus could drift off to sleep without interruption. A common complaint was that people tripped on the cable that was attached to the first remotes. It was not until 1955 that Zenith created the “Flash-matic” or their first wireless remote. While it helped keep the flow of traffic without tripping people along the way, the “Flash-matic” was not flawless. It frustrated people when the sun would hit the TV set, thus changing the channel. The remote gave viewers an opportunity to “arm” themselves. Viewers no longer watched a show because they did not want to get up......]]>certkingFri, 03 Apr 2009 03:18:49 GMThttp://blog.bitcomet.com/post/89055/MB6-510 — officially called "Lazy Bones" was connected to the television set by a wire. To improve the cumbersome setup, a wireless remote control called "Flashmatic" was developed in 1955 which worked by shining a beam of light onto a photoelectric cell. Unfortunately, the cells did not distinguish between light from the remote and light from other sources and the Flashmatic also required that the remote control be pointed very accurately at the receiver.[2] The Zenith Space Commander 600 remote control In 1956 Robert Adler developed "Zenith Space Command", a wireless remote.[3] It was mechanical and used ultrasound to change the channel and volume. When the user pushed a button on the remote control it clicked and struck a bar, hence the term "clicker". Each bar emitted a different frequency and circuits in the television detected......]]>certkingFri, 03 Apr 2009 03:17:06 GMThttp://blog.bitcomet.com/post/89054/MB5-537 and also the changer. It however, is also known as the button, mainly in North England[citation needed]. Commonly, remote controls are Consumer IR devices used to issue commands from a distance to televisions or other consumer electronics such as stereo systems and DVD players. Remote controls for these devices are usually small wireless handheld objects with an array of buttons for adjusting various settings such as television channel, track number, and volume. In fact, for the majority of modern devices with this kind of control, the remote contains all the function controls while the controlled device itself only has a handful of essential primary controls. Most of these remotes communicate to their respective devices via infrared (IR) signals and a few via radio signals.......]]>certkingFri, 03 Apr 2009 03:16:10 GMThttp://blog.bitcomet.com/post/89052/MB6-513 World Wide Web and in web services – offers an obvious example. In a synchronous model, one system makes a connection to another, sends a request and waits for a reply. In many situations this makes perfect sense; for example, a user sends a request for a web page and then waits for a reply. However, other scenarios exist in which such behaviour is not appropriate. For example, an application may need to notify another that an event has occurred, but does not need to wait for a response. Another example occurs in publish/subscribe systems, where an application "publishes" information for any number of clients to read. In both these examples it would not make sense for the sender of theMB6-512 information to have to wait if, for example, one of the recipients had crashed. Alternatively, an interactive application may need to respond to certain......]]>certkingFri, 03 Apr 2009 03:14:29 GMThttp://blog.bitcomet.com/post/89051/MB7-514 registers a software routine that "listens" for messages placed onto the queue. Second and subsequent applications may connect to the queue and transfer a message onto it. The queue-manager software stores the messages until a receiving application connects and then calls the registered software routine. The receiving application then processes the message in an appropriate manner... There are often numerous options as to the exact semantics of message passing, including: * Durability (e.g. - whether or not queued data can be merely kept in memory, or if it mustn't be lost, and thus must be stored on disk, or, more expensive still, it must be committed more reliably to a DBMS) * Security policies * Message purging policies - queues or messages may have a TTL (Time To......]]>certkingFri, 03 Apr 2009 03:13:26 GMThttp://blog.bitcomet.com/post/89049/MB4-536 queues provide an asynchronous communications protocol, meaning that the sender and receiver of the message do not need to interact with the message queue at the same time. Messages placed onto the queue are stored until the recipient retrieves them. Most message queues have set limits on the size of data that can be transmitted in a single message. Those that do not have such limits are known as mailboxes. Many implementations of message queues function internally: within an operating system or within an application. Such queues exist for the purposes of that system only. Other implementations allow the passing of messages between different computer systems, potentially......]]>certkingFri, 03 Apr 2009 03:12:56 GMThttp://blog.bitcomet.com/post/89048/MB2-498 distributed system is one in which the failure of a computer you didn't even know existed can render your own computer unusable."[1] Troubleshooting and diagnosing problems in a distributed system can also become more difficult, because the analysis may require connecting to remote nodes or inspecting communication between nodes. Many types of computation are not well suited for distributed environments, typically owing to the amount of network communication or synchronization that would be required between nodes. If bandwidth, latency, or communication requirements are too significant, then the benefits of distributed computing may be negated and the performance may be worse than a non-distributed environment. Architecture Various hardware and software architectures......]]>certkingFri, 03 Apr 2009 03:11:56 GMThttp://blog.bitcomet.com/post/89046/MB3-637 a program is split up into parts that run simultaneously on multiple computers communicating over a network. Distributed computing is a form of parallel computing, but parallel computing is most commonly used to describe program parts running simultaneously on multiple processors in the same computer. Both types of processing require dividing a program into parts that can run simultaneously, but distributed programs often must deal with heterogeneous environments, network links of varying latencies, and unpredictable failures in the network or the computers.Organizing the interaction between the computers that execute distributed computations is of prime importance. In order to be able to use the widest possible variety of computers,......]]>certkingFri, 03 Apr 2009 03:10:26 GMThttp://blog.bitcomet.com/post/89045/MB3-530 project was the Great Internet Mersenne Prime Search, which was started in January 1996.[1] It was followed in 1997 by distributed.net. In 1997 and 1998 several academic research projects developed Java-based systems for volunteer computing; examples include Bayanihan,[2] Popcorn,[3] Superweb,[4] and Charlotte.[5]. Another similar concept is Sideband computing which let a user to share his computing power while he is online. The term "volunteer computing" was coined by Luis F. G. Sarmenta, the developer of Bayanihan. It is also appealing for global efforts on social responsibility, or Corporate Social Responsibility as reported in a Harvard Business Review [6] or used in the Responsible IT forum.[7] In 1999 the SETI@home and Folding@home projects were launched.......]]>certkingFri, 03 Apr 2009 03:09:12 GMThttp://blog.bitcomet.com/post/89041/mb2-631 as a utility for commercial and noncommercial clients, with those clients paying only for what they use, as with electricity or water. Grid computing is being applied by the National Science Foundation's National Technology Grid, NASA's Information Power Grid, Pratt & Whitney, Bristol-Myers Squibb Co., and American Express.[citation needed] One of the most famous cycle-scavenging networks is SETI@home, which was using more than 3 million computers to achieve 23.37 sustained teraflops (979 lifetime teraflops) as of September 2001[update] [2]. As of March 2008, Folding@home had achieved peaks of 1,502 teraflops on over 270,000 machines. The European Union has been a major proponent......]]>certkingFri, 03 Apr 2009 02:59:49 GMThttp://blog.bitcomet.com/post/89040/MB7-639 at night, during lunch, or even in the scattered seconds throughout the day when the computer is waiting for user input or slow devices. Volunteer computing projects use the CPU scavenging model almost exclusively. In practice, participating computers also donate some supporting amount of disk storage space, RAM, and network bandwidth, in addition to raw CPU power. Since nodes are likely to go "offline" from time to time, as their owners use their resources for their primary purpose, this model must be designed to handle such contingencies. Taxation Issues in Grid Computing The project BEinGRID has studied the legal issues involved in Grid computing. In particular, the issue......]]>certkingFri, 03 Apr 2009 02:59:08 GMT