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The ZPU microprocessor is a stack machine designed to run supervisory code in electronic systems that include a field-programmable gate array (FPGA). The ZPU is notable because it is a relatively recent stack machine with a small but real economic niche, and it has a growing number of users and implementations. Many experts think that this is impossible. The ZPU has been designed to require very small amounts of electronic logic, making more electronic logic available for other purposes in the FPGA. To make it easily usable, it has a port of the GNU Compiler Collection. This makes it much easier to apply than CPUs without compilers. The ZPU is very small, but it is not fast. It keeps the intermediate results of calculations in memory, in a push-down stack, rather than in registers.〔 Zylin Corp. made the ZPU open-source in 2008.〔 == Usage == Many electronic projects include electronic logic in an FPGA. It's wasteful to also have a microprocessor, so it is commonplace to add a CPU to the electronic logic in the FPGA. Often, a smaller, less-expensive FPGA could be used if only the CPU used less resources. This is the exact situation that the ZPU was designed to address. The ZPU is designed to handle the miscellaneous tasks of a system that are best handled by software, for example, a user interface. The ZPU is very slow, but its small size helps to place any needed high-speed algorithm in the FPGA. Another issue is that most CPUs for FPGAs are closed-source, available only from a particular maker of FPGAs. Occasionally a project needs to have a design that can be widely-distributed, for security inspections, educational uses or other reasons. The licenses on these proprietary CPUs can prevent these uses. The ZPU is open-sourced. Some projects need code that must be small, but run on a CPU that inherently has larger code. Alternatively, a project may benefit from the wide selection of code, compilers and debugging tools for the GNU Compiler Collection. In these cases, an emulator can be written to implement the ZPU's instruction set on the target CPU, and the ZPU's compilers can be used to produce the code. The resulting system is slow, but packs code into less memory than many CPUs and enables the project to use a wide variety of compilers and code. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「ZPU (microprocessor)」の詳細全文を読む スポンサード リンク
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