I. Differences between ARM7 and ARM9: This article is intended for beginners who are preparing to learn ARM technology and have no idea whether to learn ARM7 or ARM9. I hope this article is useful to you. Due to the occupation, I often answer some questions from arm beginners. Although the questions are strange, the following two questions are absolutely representative. What are the differences between ARM7 and ARM9? I'm going to learn about arm, but I don't know whether to choose ARM7 or ARM9? These problems may not be a problem in the eyes of prawns, but it is necessary for beginners to find out. Let's talk about the differences between arm7. 1. clock frequency Improvement Although the kernel architecture is the same as that of ARM7, the ARM7 processor adopts the Feng nuiman structure with a three-level pipeline, while ARM9 adopts the Harvard structure with a five-level pipeline. The added pipeline design improves clock frequency and parallel processing capabilities. The five-level pipeline can allocate each instruction processing time to five clock cycles, and five commands are executed simultaneously in each clock cycle. In common chip production processes, ARM7 generally runs at around MHz, while ARM9. 2. instruction cycle Improvement The improvement of the instruction cycle is of great help to improve the processor performance. The performance improvement depends on the overlapping of commands during code execution, which is actually a problem of the program itself. For the most advanced language, the performance is generally improved by about 30%. 3. MMU (Memory Management Unit) Generally, there is no MMU (Memory Management Unit) in the arm720t and MMU in the arm720t ).
Arm9940t only has MPU, not a complete MMU. This is important because MMU units are required for large operating systems, such as Linux and wince. This is to say, generally can only run a small real-time system such as UCOS-II, ECOs, and so on, and arm9-without this restriction, the general operating system can be transplanted. In fact, even if arm720t can support Linux, WinCE, and other systems, it is rare to use it because it is a little difficult to run such a large operating system at the operating speed of arm70. In addition, the application fields of the two are obviously different, and this is not necessary. 4. ARM7 provides better performance-power consumption ratio than ARM9. It contains the kernel of thumb instruction set fast multiplication instruction and ice debugging technology. 5. in the process of transforming from the platform of ARM7 to the platform of arm9e, one thing is very fortunate, that is, arm9e can be fully backward compatible with the software of arm7; in addition, the programming model and architecture infrastructure faced by developers are consistent. 2. Do beginners choose ARM7 or ARM9? 1) define the purpose
Learning is an application. Where are you going to use arm? If it is a general control system or only used to replace 8-bit and 16-bit machines, the ARM7 is obviously the first choice; but if it is used for network communication or large-scale audio/video processing, then, ARM9. 2) Basic
There are generally three types of people learning arm: First, computer majors: these people have a lot of knowledge about software such as operating systems, but little knowledge about hardware. Obviously, this kind of people learn about arm is still good at software and can be based on Linux; the operating system such as WinCE can better meet the requirements of such people. Of course, many computer professionals are also engaged in the compilation of the application software of the ARM7 system. However, there is very little at the bottom layer. Second, electronics Majors: these people have a relatively good hardware base, while on the contrary, the knowledge of operating systems, databases and other software is unsatisfactory. Therefore, many electronic professionals are familiar with single-chip microcomputer, but it is still difficult to write small programs in a single chip. However, using arm for large-scale software is not enough, especially for Linux; windows XP is not an easy solution for three or two months. It is recommended that such personnel do not need to learn from the ARM7 and small operating systems. If it is enough, do not blindly pursue the high-end. One thing to note is that, instead of engaging in arm, the salary is higher than that of arm, but there are more job opportunities than arm. This is a good understanding. It is like the pyramid. Third, the hardware and software basics are not good: such personnel have real needs and are also fashionable. If there is no great determination to learn, it is better to participate in the training. Of course, it can also save the country by curve. After Understanding single-chip microcomputer, it will not be difficult for them. Finally, it is really necessary for beginners to buy a Development Board about the Development Board, but they also need to choose the right one. For Beginners, there is a complete set of materials, supporting tutorials and learning guidance, and timely technical support. At present, there are very few achievements. The Development Board is not to say which company is famous. After-sales is good. Many large companies generally ignore the problem of individual buyers. I feel that it is mostly luck, if you're lucky, you may have a good after-sales experience. |
