This chapter presents the following content: Keyboard/monitor, disk drive, suggested reading: stallings chapter 7. | Chapter 07 Computer Organization and Architecture INPUT/OUTPUT 1 KEY POINTS The computer system’s I/O architecture is its interface to the outside world. The are three principal I/O techniques: Programmed I/O, in which I/O occurs under the direct and continuous control of the program requesting the I/O operation. Interrupt-driven I/O, in which a program issues an I/O command and then continues to execute, until it is interrupted by the I/O hardware to signal the end of the I/O operation. Direct memory access (DMA), in which a specialized I/O processor takes over control of an I/O operation to move a large block of data. Why I/O Modules and Function? In addition to the processor and a set of memory modules, the third key element of a computer system is a set of I/O modules. There are a wide variety of peripherals with various methods of operation. It would be impractical to incorporate the necessary logic within the processor to control a range of devices. The data transfer rate of . | Chapter 07 Computer Organization and Architecture INPUT/OUTPUT 1 KEY POINTS The computer system’s I/O architecture is its interface to the outside world. The are three principal I/O techniques: Programmed I/O, in which I/O occurs under the direct and continuous control of the program requesting the I/O operation. Interrupt-driven I/O, in which a program issues an I/O command and then continues to execute, until it is interrupted by the I/O hardware to signal the end of the I/O operation. Direct memory access (DMA), in which a specialized I/O processor takes over control of an I/O operation to move a large block of data. Why I/O Modules and Function? In addition to the processor and a set of memory modules, the third key element of a computer system is a set of I/O modules. There are a wide variety of peripherals with various methods of operation. It would be impractical to incorporate the necessary logic within the processor to control a range of devices. The data transfer rate of peripherals is often much slower than that of the memory or processor. Thus, it is impractical to use the high-speed system bus to communicate directly with a peripheral. On the other hand, the data transfer rate of some peripherals is faster than that of the memory or processor. Again, the mismatch would lead to inefficiencies if not managed properly. Peripherals often use different data formats and word lengths than the computer to which they are attached. Why I/O Modules and Function? Thus, an I/O module is required. This module has two major functions Interface to the processor and memory via the system bus or central switch Interface to one or more peripheral devices by tailored data links Why I/O Modules and Function? Figure . Generic Model of an I/O Module . External Devices I/O operations are accomplished through a wide assortment of external devices that provide a means of exchanging data between the external environment and the computer. An external device attaches to the
