8259 010U1000

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8259 is an Intel Programmable Interrupt Controller (PIC) chip which is commonly used in PC systems. It is designed to handle multiple interrupts in an efficient way that saves system resources while minimizing the number of system resources required. The 8259 has a wide range of applications in the field of computer hardware, ranging from simple memory and I/O mapping tasks to complex applications like software interrupts. In this article, we shall discuss the 8259 chip\'s application field and how its working principle applies in practice.

8259 can be used in the field of microcomputer systems for several purposes including interrupt generation and handling. It serves as an interface between the system and the hardware devices, enabling them to communicate in an efficient manner. The chip can be used to generate software interrupts for hardware events or to combine the status of various input pins on a chip to produce a single software interrupt. In addition, the 8259 chip can be used to multiplex multiple input pins, allowing a single interrupt line to be used to access multiple peripherals. This functionality is particularly useful in multimedia applications like multi-touch gestures or video capture.

In terms of its working principle, the 8259 chip utilises a two-level interrupt architecture in order to handle multiple incoming interrupts. At the first level, an interrupt is first acknowledged by the 8259 and then control is passed to the second level, where the interrupt is serviced. During the second level, the correct interrupt vector is applied so that the correct ISR can be called. This architecture ensures that the processor is not interrupted unnecessarily and that the privilege level of the executing process is not changed.

In a real-time system, the 8259 can be configured to trigger an interrupt whenever an input line is activated. This can be used to detect when a button is pressed or an analog signal is received. The 8259 can then inform the operating system of this event so that the appropriate handler can be called. This can be used to increase the responsiveness of the system to external events and can be very helpful in applications like video streaming and automation.

Another application of 8259 is in the field of memory-mapping. The chip can be programmed to map internal memory addresses to external locations on a memory bus. This allows for faster retrieval of data and access to memory for various peripherals. IRQ lines can also be assigned to specific memory locations so that they can be used as interrupts for certain operations. This capability can be useful when dealing with large data sets where quick access to individual memory locations is required.

The 8259 also supports bus arbiter mode, which is essential for allowing multiple devices to share a single data bus. In this mode, the 8259 acts as a coordinator for the operations of multiple devices connected to it. It arbiters who should gain access to the data bus and at what rate. This ensures that one device does not overload the bus and that all devices connected to the bus get the best performance and experience.

The 8259 chip can be found in a wide range of computer systems. It can be used for low-level hardware tasks such as I/O mapping and interrupt handling, to more complex tasks like memory mapping and bus arbiter control. It provides highly efficient and reliable control over multiple peripherals, ensuring optimal performance for all connected devices. The 8259 can be an invaluable asset for computer systems for both home and business use.

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