I/O and File Management Quiz

I/O Management and File Management

• I/O Management encompasses I/O devices, organization of I/O functions, I/O buffering, hardware organization, and device/disk scheduling policies (FIFO, LIFO, SSTF, SCAN, CSCAN).
• File Management includes file overview, file organization and access, file directories, file sharing, record blocking, secondary storage management, and Android file management.

I/O Devices

• Input/output (I/O) is the collection of interfaces that distinct functional units of an information processing system use for communication.
• Inputs are received signals by a unit, and outputs are signals sent from that unit.
• I/O devices allow people to communicate with computers.

Organization of an I/O function

• Three techniques for performing I/O include programmed I/O, interrupt-driven I/O, and Direct Memory Access (DMA).
• Programmed I/O: The processor issues an I/O command, and waits for the operation to complete, checking I/O module status until completion.
• Interrupt-driven I/O: The processor issues an I/O command, and doesn't wait. The I/O module interrupts the processor when the operation is complete.
• DMA: A DMA module controls data exchange between main memory and an I/O module, without processor intervention.

Categories of I/O

• External devices for I/O are categorized as human readable, machine readable, and communication devices.
• Human readable: suitable for human interaction, such as keyboards, mice, terminals and printers.
• Machine readable: suitable for exchanging data with hardware, such as disk drives, USB keys, sensors, and controllers.
• Communication: suitable for remote device interaction, such as modems and digital line drivers.

Direct Memory Access (DMA)

• DMA is a hardware subsystem that allows certain hardware to access main memory independently of the CPU.
• DMA allows peripheral devices to access the main memory bus directly, which speeds up data transfer.

I/O Buffering

• Buffering is used to effectively handle speed mismatches between data producers and consumers.
• A buffer, stored in main memory, temporarily holds data received from a device such as a modem.
• Data is transferred to a secondary storage device (like a disk) from this buffer in a single operation.
• Buffering minimizes delays due to unequal transfer speeds of different devices.

Types of I/O Buffering

• Single buffer
• Double buffer
• Circular buffer

File Systems in Operating Systems

• Files are named collections of related information on secondary storage.
• File structure is defined by structure characteristics (e.g., bits, bytes, lines, records).
• File types include text, source, object, and executable files.
• File attributes include name, type, location, size, protection, and timestamp.
• Sample file types include video, audio, image, and other executable types (.avi, .acc, .jpg, .apk, etc.).

File Structure

• A field is an elementary data unit
• A record is a collection of related data fields
• A file is a collection of similar records
• Database is a collection of related data

Access Methods for Files

• Sequential access: Reading records one by one sequentially
• Random/Direct access: Ability to access any record without sequential traversal
• Indexed access: Access to data based on a file index, such as a search index that allows jumping to a point rapidly.

Disk Structure

• Magnetic disks are circular plates coated with a magnetized material.
• Plates are stacked on a spindle to form a disk pack.
• Data is stored on tracks and sectors on the surface.

Disk Performance Parameters

• Seek time: Time taken to position the read/write head at the desired track
• Rotational delay/latency: Time to position the desired sector under the head.
• Access time: Total time to access the desired data (seek time + rotational delay)
• Transfer time: Time for data transfer

Disk Scheduling Algorithms

• FCFS (First-Come, First-Served): Processes requests in order received
• SSTF (Shortest Seek Time First): Selects the request with the shortest seek time
• SCAN: Disk arm moves linearly across the disk
• C-SCAN: Linear scan then reverses direction

Test your knowledge on I/O management and file management concepts, including I/O devices, buffering techniques, and file organization. This quiz covers essential policies like FIFO, LIFO, and various I/O operation techniques. Ideal for computer science students or those looking to refresh their knowledge in operating systems.