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Integrated circuit
Fri Apr 3, 09 04:41 AM | Category: All
In electronics, an integrated circuit (also known as IC, microcircuit, microchip, silicon chip, or chip) is a miniaturized electronic circuit (consisting mainly of semiconductor devices, as well as passive components) that has been manufactured in the surface of a thin substrate of semiconductor material. Integrated circuits are used in almost all electronic equipment in use today and have revolutionized the world of electronics. A hybrid integrated circuit is a miniaturized electronic circuit constructed of individual semiconductor devices,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.......
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Data format
Fri Apr 3, 09 03:49 AM | Category: All
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......
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File Transfer Protocol
Fri Apr 3, 09 03:46 AM | Category: All
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......
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Recent developments
Fri Apr 3, 09 03:45 AM | Category: All
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&......
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Swapping
Fri Apr 3, 09 03:43 AM | Category: All
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......
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Random-access memory
Fri Apr 3, 09 03:42 AM | Category: All
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......
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Security and spamming
Fri Apr 3, 09 03:41 AM | Category: All
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......
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Outgoing mail SMTP server
Fri Apr 3, 09 03:40 AM | Category: All
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......
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Simple Mail Transfer Protocol
Fri Apr 3, 09 03:39 AM | Category: All
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......
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Persistence (computer science)
Fri Apr 3, 09 03:37 AM | Category: All
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......
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