computerterm, also known as Backwards compatibility
also calledBackwards compatibility），computerTerminology.Downward compatibility is often relative toUpward compatibilityIn terms of compatibility, the two concepts are opposite, so the two concepts are different.Downward Compatibility is also called Backward Compatibility.In a computer, referring to a program orClass libraryUpdate to newereditionAfter that, the document or system created with the old version of the program can still be operated or used normally, or the program developed on the basis of the old version of the class library can still be compiled and run normally.For example, a higher grade computer or a higher version software platform can run programs developed by a lower grade computer or an earlier software platform. For example, a PC compatible computer based on a Pentium microprocessor can run all software running on a 486 earlier.Downward compatibility allows users to upgrade software or hardware without the need for manufacturers to compile applications from scratch for new devices or platforms. The previous programs are still valid in the new environment.
For software, backward compatibility means that a higher version of the program can successfully process the data of a lower version of the program.Take famous animation softwareFlashThe two versions of Flash 5 and Flash MX 2004 are both.fla, but the structure of the file content is different.However, Flash MX 2004 can still handleFlash 5.0For the saved fla file, we say that Flash MX 2004 is backward compatible.
Generally, when updating a software, some consideration should be given to downward compatibility, which can often bring convenience to users and better retain them.MicrosoftSpecial emphasis is placed on maintaining downward compatibility of software.In order to achieve this goal, sometimes Microsoft even supports software that uses unofficial or even misused APIs.[1]
Software
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stayfile systemMedium,ext4The design of the file system is backward compatible. The ext3 file system can be mounted as an ext4 file system.
Generally, when updating a software, some consideration should be given to downward compatibility, which can often bring convenience to users and better retain them.MicrosoftSpecial emphasis is placed on maintaining downward compatibility of software.In order to achieve this goal, sometimes Microsoft even supports software that uses unofficial or even misused APIs.
However, this is not always the case. Sometimes, considering downward compatibility will bring some burdens, or even increase the development cost, especially moreupgradeAfter.Python3.0 is an example of giving up backward compatibility.
If the documents saved in the old version of a software cannot be read by the new version, even if the manufacturer provides additional tools to convert the old documents irreversibly, this cannot be called backward compatibility.This may be a marketing strategy of software manufacturers to force users to buy upgraded softwareupgradeThe number of users increases gradually, and the number of documents that can be read by old software decreases gradually.[2]
Hardware
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Widely useduniversal serial bus (USB) For example, from version 1.1 in 1998 to version 3.1 in 2015, plug and socket of type A can be used across versions. Only the large transmission rate and some new features supported by the new version cannot be used by the old version.
Blu ray optical driveGenerally backward compatible readingDVD、CD。
In addition, Microsoft launchedXbox OneGame console pairXbox 360, andNintendoLaunchedWii UyesWiiThe old version of the game is supported in the new version of the hardware.howeverSony Computer EntertainmentLaunchedPS4The game console is not backward compatiblePS3's game.[1]
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Negative impact of downward compatibility
However, this is not always the case. Sometimes considering downward compatibility will bring some burdens, especially after many upgrades.Python 3.0This is an example of giving up backward compatibility.
The situation that cannot be called downward compatibility
If the documents saved in the old version of a software cannot be read by the new version, even if the manufacturer provides additional tools to convert the old documents irreversibly, this cannot be called backward compatibility.This may be a marketing strategy of software manufacturers to force users to buy upgraded software. As the number of upgraded users increases, the number of documents that can be read by old software gradually decreases.[2]
