Interleaved addressing was implemented to support cache line fills tarting at a non-aligned address or if your cache line takes 4 words and your processor askes for word 2, the cache would start filling with word 2, then 3, then complete the line by filling words 0 and then 1. This reduces latency (e.g., intel processors).
For most FPGA applications it is better to stay away from interleaved addressing because it complicates design and restricts the maximum burst size of an access.(1)
Interleaving in disk storage
Low-level format utility performing interleave speed tests on a 10-megabyte IBM PC XT hard drive.
Interleaving was used in ordering block storage on disk-based storage devices (e.g., floppy disk and the hard disk). The primary purpose of interleaving was to adjust the timing differences between ready to transfer data, and data arriving at the drive head to be read. Interleaving was very common prior to the 1990s; but modern disk storage is not interleaved because processing speeds increased.
Interleaving was used for sector efficiency; after reading a sector, time would be permitted for processing, and then the next sector in sequence is ready to be read. Matching the sector interleave to the processing speed accelerates the data transfer, but incorrect interleave slows the system.
Example
Information is stored on disk storage (very small pieces) referred to as sectors or blocks. These are arranged in concentric rings (tracks) across the surface of each disk. Ordering these blocks in direct serial order in each track, such as 1 2 3 4 5 6 7 8 9, for early computing devices was not practical.
Data to be written or read is put into a special region/reusable memory or buffer. When data needed to be written, it was moved into the buffer, and then written from buffer to disk and reading was the reverse. Early computers were not fast enough to read a sector, move the data from the buffer to somewhere else, and be ready to read the next sector by the time that next sector was appearing under the read head.
In direct serial order, after the first sector was read the computer waits for three sectors to pass by before it is ready to receive data again; in direct order, sector two, three, and four have already passed by. The computer doesn't need sectors 4, 5, 6, 7, 8, 9, or 1, and must wait for these to pass by, before reading sector two waiting slows the data transfer rate.
To correct delays, the ideal interleave for this system would be 1:4, ordering the sectors like this: 1 8 6 4 2 9 7 5 3. It reads sector 1, processes for three sectors whereby 8 6 and 4 pass by, and just as the computer becomes ready again, sector two is arriving just as it is needed. Sometimes the interleave is expressed as a "skip factor", the number of physical sectors between consecutive logical sectors. A skip factor of 0 places the sectors sequentially—1 2 3 4 5 6 ... .
Modern disk storage does not use interleaving because buffer space is now so much larger. Data is now stored as clusters which are groups of sectors, and the data buffer is sufficiently large to allow all sectors in a block to be read at once without any delay.
Interleaving in error-correction coding
Interleaving is used in digital communication and storage systems to improve the performance of forward error correcting codes. Many communication channels are not memoryless: errors typically occur in bursts. If the number of errors within a code word exceeds the error-correcting code's capability, it fails to recover the original code word. Interleaving solves this problem with movement of source symbols across several code words, and more uniform distribution of errors.(2)
(1)<http://www.embeddedrelated.com/usenet/embedded/show/60826-1.php>. Web. 6 Nov. 2011.
(2)<http://en.wikipedia.org/wiki/Interleaving>. Web. 6 Nov. 2011.
a b B. Vucetic, J. Yuan (2000). Turbo codes: principles and applications. Springer Verlag. ISBN 978-0792378686.
Tuesday, November 8, 2011
Applets
An applet is a program written in the Java programming language included in an HTML page, much in the same way an image is included in a page. When you use a Java technology-enabled browser to view a page that contains an applet, the applet's code is transferred to your system and executed by the browser's Java Virtual Machine (JVM).
Java Plug-in software enables enterprise customers to direct applets or beans written in the Java programming language on their intranet web pages to run using Sun's Java Runtime Environment (JRE), instead of the browser's default. This enables an enterprise to deploy applets that take full advantage of the latest capabilities and features of the Java platform and be assured that they will run reliably and consistently.(15)
In computing, an applet is any small application that performs one specific task in a larger program, (e.g., as a plug-in).[1][2] An applet usually is a Java applets, i.e., programs written in the Java programming language in a web page." The word Applet was first used in 1990 in PC Magazine."[3]
Provided that an applet is hosted by an operating system, it can function as any other normal software application but is small and performs small tasks. Examples of applications as applets are Windows Notepad or Microsoft Paint. Applets are not full-featured application programs and can be extensions of software through a plug-in or mobile devices that support the applet programming model.[2]
Applets are used to provide interactive features that cannot be provided by HTML alone through mouse input or controls like buttons or check boxes and change the provided graphic content well suitable for demonstration, visualization, and teaching. Applet collections for studying various subjects, from physics[4] to heart physiology are popular.[5] Applets are also used to create online game collections and players can compete against live opponents in real-time.
An applet can also be a text area only, providing, for instance, a cross platform command-line interface to some remote system.[6] If needed, an applet can leave the dedicated area and run as a separate window. However, applets have very little control over web page content outside the applet dedicated area, so they are less useful for improving the site appearance in general (while applets like news tickers[7] or WYSIWYG editors[8] are also known). Applets can also play media in formats that are not naively supported by the browser[9]
HTML pages may embed parameters that are passed to the applet. Hence the same applet may appear differently depending on the parameters that were passed.
Examples of Web-based Applets include: QuickTime movies, Flash movies, Windows Media Player applets, used to display embedded video files in Internet Explorer (and other browsers that support the plug- in), 3D modeling display applets, used to rotate and zoom a model, Browser games can be applet-based, though some may develop into fully functional applications that require installation.
Applets execute only on the "client" platform environment versus "servlet" and provides functionality or performance beyond the the browser. The container restricts applets' capabilities. Applets are written in a compiled language, and the scripting language of the container is an interpreted language, and leads to greater performance or functionality of the applet or a complete web component can be implemented as an applet.
Java Applet
Java Applets can provide web applications with interactive features above HTML. Since Java's bytecode is platform-independent, Java applets can be executed by many platforms of browsers. "When a Java technology-enabled web browser processes a page that contains an applet, the applet's code is transferred to the client's system and executed by the browser's Java Virtual Machine (JVM).[10] An HTML page references an applet either via the deprecated <APPLET> tag or via its replacement, the <OBJECT> tag."[11]
Security
Developments in coding of applications (mobile and embedded systems) indicate the security of applets.
Open Platform Applets
Applets in an open platform environment provide secure interactions between applications through a compositional approach and also with advanced compositional verification methods.[12]
Java Applets
A Java applet contains various security models: unsigned Java applet security, signed Java applet security, and self signed Java applet security.
Web-based Applets
In an applet-enabled web browser security methods counter malicious applets that may cause denial of service, invasion of privacy, and annoyance.[13] AppletGuard by monitoring applets can stop malicious applets successfully..[13]
(1) "AskOxford: applet", Oxford Dictionaries. Accessed on July 21, 2009
(2) a b "applet: Definition from Answers.com", Answers.com. Accessed on July 21, 2009
(3)"Oxford English Dictionary". 2011. Retrieved 2011-08-23.
(4) Paul Falstad online applet portal
(5) The virtual hearth
(6) Jraft.com
(7) ObjectPlanet.com, an applet that works as news ticker
(8) Sferyx.com, a company that produces applets acting as WYSWYG editor.
(9) Cortado applet to play ogg format
(10) "Applets", Sun Developer Network. Accessed on July 21, 2009
(11)"HTML applet tag", W3Schools. Access on July 21, 2009
(12) a b Barthe, Gilles; Gurov, Dilian; Huisman, Marieke (2002). "Compositional Verification of Secure Applet Interactions". Retrieved 2010-04-10.
(13)a b Hassler, Vesna; Then, Oliver (1998). "Controlling Applets' Behavior in a Browser". Retrieved 2010-04-10.
(14) <http://en.wikipedia.org/wiki/Applet>. Web. 6 Nov. 2011.
(15)<http://www.oracle.com/us/sun/index.htm>. Web. 5 Nov. 2011.
Java Plug-in software enables enterprise customers to direct applets or beans written in the Java programming language on their intranet web pages to run using Sun's Java Runtime Environment (JRE), instead of the browser's default. This enables an enterprise to deploy applets that take full advantage of the latest capabilities and features of the Java platform and be assured that they will run reliably and consistently.(15)
In computing, an applet is any small application that performs one specific task in a larger program, (e.g., as a plug-in).[1][2] An applet usually is a Java applets, i.e., programs written in the Java programming language in a web page." The word Applet was first used in 1990 in PC Magazine."[3]
Provided that an applet is hosted by an operating system, it can function as any other normal software application but is small and performs small tasks. Examples of applications as applets are Windows Notepad or Microsoft Paint. Applets are not full-featured application programs and can be extensions of software through a plug-in or mobile devices that support the applet programming model.[2]
Applets are used to provide interactive features that cannot be provided by HTML alone through mouse input or controls like buttons or check boxes and change the provided graphic content well suitable for demonstration, visualization, and teaching. Applet collections for studying various subjects, from physics[4] to heart physiology are popular.[5] Applets are also used to create online game collections and players can compete against live opponents in real-time.
An applet can also be a text area only, providing, for instance, a cross platform command-line interface to some remote system.[6] If needed, an applet can leave the dedicated area and run as a separate window. However, applets have very little control over web page content outside the applet dedicated area, so they are less useful for improving the site appearance in general (while applets like news tickers[7] or WYSIWYG editors[8] are also known). Applets can also play media in formats that are not naively supported by the browser[9]
HTML pages may embed parameters that are passed to the applet. Hence the same applet may appear differently depending on the parameters that were passed.
Examples of Web-based Applets include: QuickTime movies, Flash movies, Windows Media Player applets, used to display embedded video files in Internet Explorer (and other browsers that support the plug- in), 3D modeling display applets, used to rotate and zoom a model, Browser games can be applet-based, though some may develop into fully functional applications that require installation.
Applets execute only on the "client" platform environment versus "servlet" and provides functionality or performance beyond the the browser. The container restricts applets' capabilities. Applets are written in a compiled language, and the scripting language of the container is an interpreted language, and leads to greater performance or functionality of the applet or a complete web component can be implemented as an applet.
Java Applet
Java Applets can provide web applications with interactive features above HTML. Since Java's bytecode is platform-independent, Java applets can be executed by many platforms of browsers. "When a Java technology-enabled web browser processes a page that contains an applet, the applet's code is transferred to the client's system and executed by the browser's Java Virtual Machine (JVM).[10] An HTML page references an applet either via the deprecated <APPLET> tag or via its replacement, the <OBJECT> tag."[11]
Security
Developments in coding of applications (mobile and embedded systems) indicate the security of applets.
Open Platform Applets
Applets in an open platform environment provide secure interactions between applications through a compositional approach and also with advanced compositional verification methods.[12]
Java Applets
A Java applet contains various security models: unsigned Java applet security, signed Java applet security, and self signed Java applet security.
Web-based Applets
In an applet-enabled web browser security methods counter malicious applets that may cause denial of service, invasion of privacy, and annoyance.[13] AppletGuard by monitoring applets can stop malicious applets successfully..[13]
(1) "AskOxford: applet", Oxford Dictionaries. Accessed on July 21, 2009
(2) a b "applet: Definition from Answers.com", Answers.com. Accessed on July 21, 2009
(3)"Oxford English Dictionary". 2011. Retrieved 2011-08-23.
(4) Paul Falstad online applet portal
(5) The virtual hearth
(6) Jraft.com
(7) ObjectPlanet.com, an applet that works as news ticker
(8) Sferyx.com, a company that produces applets acting as WYSWYG editor.
(9) Cortado applet to play ogg format
(10) "Applets", Sun Developer Network. Accessed on July 21, 2009
(11)"HTML applet tag", W3Schools. Access on July 21, 2009
(12) a b Barthe, Gilles; Gurov, Dilian; Huisman, Marieke (2002). "Compositional Verification of Secure Applet Interactions". Retrieved 2010-04-10.
(13)a b Hassler, Vesna; Then, Oliver (1998). "Controlling Applets' Behavior in a Browser". Retrieved 2010-04-10.
(14) <http://en.wikipedia.org/wiki/Applet>. Web. 6 Nov. 2011.
(15)<http://www.oracle.com/us/sun/index.htm>. Web. 5 Nov. 2011.
Subscribe to:
Comments (Atom)