IOCS
Input/Output Control System
Enhanced Definition
The portion of the operating system that manages all input and output operations, handling physical I/O, buffering, error recovery, and device management.
Key Characteristics
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- Physical I/O management
- Buffer management
- Error detection and recovery
- Device allocation
- Channel program execution
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IOCS Functions:
- Channel Programs: I/O instruction sequences
- Buffer Pool Management: Memory allocation for I/O
- Device Management: Allocation and deallocation
- Error Handling: Retry and recovery
- I/O Scheduling: Optimize device utilization
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I/O Processing:1. Program issues I/O request 2. IOCS builds channel program 3. Channel executes I/O operation 4. Device performs physical I/O 5. Completion interrupt 6. IOCS processes completion 7. Data available to program
Use Cases
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- All dataset and device I/O
- Tape and DASD operations
- Network communications
- Terminal I/O
- Printer and output management
Related Concepts
Related to: Channel, Access Method, Device Driver, Buffer