Persistence: Storage Devices & File Systems Flashcards
What is the purpose of storing an operating system on a device like a hard drive or SSD?
Answer: To save data in a way that survives even when the power is turned off and to load the OS into memory when the computer starts.
What is the role of General Input/Output (I/O) in a computer system?
Answer: To manage inputs from input devices and outputs to output devices, connecting hardware components with the central CPU through various types of bus (interconnect).
Why do I/O interfaces evolve quickly over the decades?
Answer: Due to changes in technology and the need for more efficient, faster communication protocols.
What is the function of a controller inside an I/O device?
Answer: To run firmware code that implements the device’s functionality, controls the device media, and provides an interface to the rest of the system.
Describe the difference between polling and interrupts in CPU-device communication.
Answer: Polling involves the CPU repeatedly checking the device’s status, while interrupts involve the device sending a signal to the CPU when it’s ready or has completed a task.
What are the drawbacks of using polling and interrupts?
Answer: Polling can waste CPU time, and too frequent interrupts can overwhelm the CPU (leading to livelock).
Explain the concept of Direct Memory Access (DMA) in I/O operations.
Answer: DMA is a special hardware component that orchestrates transfers between devices and main memory without much CPU intervention.
What is memory-mapped I/O?
Answer: A method where modern computers treat device controls as if they’re part of the regular memory, allowing the CPU to interact with devices using common memory operations.
What is the purpose of the OS software stack in terms of I/O operations?
Answer: To hide the complexities of I/O protocols from users and provide a cleaner interface through multiple layers of abstractions, including device drivers.
