tailieunhanh - HandBooks Professional Java-C-Scrip-SQL part 189

Tham khảo tài liệu 'handbooks professional java-c-scrip-sql part 189', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | single printer. The user of the device connects one computer to each serial port and a printer to the parallel port. Both computers can then send documents to the printer though only one of them can do so at a given time. In order to illustrate the flow of data through the printer-sharing device I ve drawn the diagram in Figure 5-1. Only those hardware devices that are involved in this application of the Arcom board are shown. By looking at the block diagram you should be able to quickly visualize the flow of the data through the system. Data to be printed is accepted from either serial port held in RAM until the printer is ready for more data and delivered to the printer via the parallel port. The software that makes all of this happen is stored in ROM. Figure 5-1. Data-flow diagram for the printer-sharing device Once you ve created a block diagram don t just crumple it up and throw it away. You should instead put it where you can refer to it throughout the project. I recommend creating a project notebook or binder with this data-flow diagram on the first page. As you continue working with this piece of hardware write down everything you learn about it in your notebook. You might also want to keep notes about the software design and implementation. A project notebook is valuable not only while you are developing the software but also once the project is complete. You will appreciate the extra effort you put into keeping a notebook when you need to make changes to your software or work with similar hardware months or years later. If you still have any big-picture questions after reading the hardware documents ask a hardware engineer for some help. If you don t already know the hardware s designer take a few minutes to introduce yourself. If you have some time take him out to lunch or buy him a beer after work. You don t even have to talk about the project the whole time I have found that many software engineers have difficulty communicating with hardware engineers