The W82C59, likely referring to the W82C59A Programmable Interrupt Controller (PIC), is a crucial component in many older computer systems and embedded devices. Manufactured by Winbond, this chip manages interrupts from various peripherals, ensuring that the CPU can efficiently handle multiple tasks. It is a versatile device that can be configured to prioritize different interrupt sources, allowing for flexible system design.

Applications

• PC motherboards (older generations)
• Industrial control systems
• Embedded systems
• Data acquisition systems
• Early personal computers and peripherals

Features

• 8 Interrupt Inputs: Handles up to 8 interrupt requests from peripheral devices.
• Programmable Priority: Allows assigning different priorities to interrupt sources, ensuring that critical tasks are handled promptly.
• Masking Capability: Individual interrupt inputs can be masked, disabling them from generating interrupts.
• Cascadable: Multiple W82C59A chips can be cascaded to handle more than 8 interrupt sources.
• Fully Static Operation: Operates without needing a minimum clock frequency.
• TTL Compatibility: Compatible with standard TTL logic levels.

Benefits

• Efficient Interrupt Management: Enables the CPU to handle multiple interrupt requests efficiently.
• Prioritized Interrupt Handling: Ensures that high-priority tasks are processed before lower-priority ones.
• Flexibility: Programmable features allow for customization to meet specific application requirements.
• Improved System Performance: By managing interrupts effectively, the system can respond more quickly to events.
• Reduced CPU Overhead: The PIC handles interrupt arbitration, reducing the load on the CPU.

Additional Details

The W82C59A typically operates with a 5V power supply. It communicates with the CPU via the system bus. Programming the W82C59A involves writing to specific control registers to configure its operation. The Interrupt Request (IRQ) lines from peripheral devices are connected to the W82C59A's interrupt inputs. When an interrupt is triggered, the W82C59A signals the CPU via the Interrupt Request (INT) pin. The CPU then acknowledges the interrupt and reads the interrupt vector from the W82C59A to determine which interrupt service routine to execute. Detailed timing diagrams and programming information are available in the W82C59A datasheet. Careful attention to the interrupt priority levels and masking is crucial for proper system operation. Cascade mode is enabled by configuring specific control bits within the chip. Proper decoding of the chip select signal is required for reliable operation. The End Of Interrupt (EOI) command must be issued by the interrupt service routine to allow the W82C59A to process subsequent interrupts.