Up-compatible (upward Compatible) up-compatible (upward Compatible), also known as forward-compatible (foreward compatibility). A program written on a lower-level computer in a computer can run on the same series of higher-end computers, or a program written in a lower-version environment of a platform can run in a later version of the environment, known as up-compatible, which is hardware-compatible, and the latter is software-compatible, for example, based on All software on the INTEL386 PC compatible machine can also be run on a 486 or higher model. Upward compatibility has very important significance, some large-scale software development, the workload is great, such as the software can be compatible, you do not need to re-development on other machines, you can save huge human and material resources. Backwards compatibility (downward Compatible) backwards compatible (downward compatibility), also referred to as backwards (backward compatibility). When a computer is updated to a newer version of a program or class library, a document or system created with the old version of the program can still be operated or used, or a program developed on the basis of an older version of the class library will still compile and run normally. For example, higher-end computers or newer software platforms can run programs that are more resistant to computer or earlier software platforms, such as the Pentium microprocessor-based PC compatibility machine that can run all of the software that was running early on 486. Backward compatibility allows users to upgrade software or hardware without having to start the application from scratch for new devices or platforms, and the previous program is still valid in the new environment. For software, backwards compatibility means that a higher version of the program can successfully handle data from lower versions of the program. With the famous animation software Flash two versions Flash 5 (old version) and Flash MX 2004 (new edition), these two versions, although the files are saved are . FLA, but the structure of the file content is different. Nonetheless, the Flash MX 2004 can still handle flash 5 saved FLA files, and we say flash MX 2004 is backwards compatible. But due to the practical application, it is not always possible for all versions of the software to accept the software output of a low version, for example, suppose there is a software X, and assume that there are now 10.0 versions (so fast. ), then the version of the old has no one to use the X 1.0 output of the file, it is less likely in 10.Successfully read in version 0. Summing up and backwards compatibility can actually be a different description of the same thing in two ways. For example, the program A that we developed for the JDK1.4 platform can run normally on the JDK1.5 platform, then we say: Program A is compatible with the JDK1.5 platform, and the JdK1.5 platform is backwards-backward to program B. If the program a we developed for the JDK1.4 platform does not function properly on the JDK1.5 platform, then we say: Program A is not up to the J DK1.5 platform, and the JdK1.5 platform is not backwards compatible with program B. Of course this does not happen. The JDK platform is backwards compatible with all Java programs. If the program B we developed for the JDK1.5 platform does not function properly on the JDK1.4 platform without using the new features of the JDK1.5 platform, then we can say: Program B is backwards compatible with JDK1.4 platform, and JdK1.4 platform is up to program B. If the program we developed for the JDK1.5 platform does not function properly on the JDK1.4 platform because of the new features or other reasons for using the JDK1.5 platform, then we can say that program B is not backwards compatible with the JDK1.4 platform, and the JdK1.4 platform is not up to compatibility with program B.
Original address: http://blog.csdn.net/hudashi/article/details/7062839