Day 01Part 13 – General purpose register list of open files and list of open devices.

Day 01Part 13 – General purpose register list of open files and list of open devices.

 General Purpose Registers, List of Open Files, and List of Open Devices

In an Operating System (OS), registers, open files, and open devices are essential for process management and system execution.

 General Purpose Registers (GPRs)

General Purpose Registers are used by the CPU to store temporary data, addresses, or instructions during execution. They improve efficiency by minimizing memory access.

 Examples of General Purpose Registers in a CPU:

• AX, BX, CX, DX (in x86 architecture)
• R0 – R31 (in modern RISC architectures)

 List of Open Files in an OS

An Operating System maintains a table of open files to keep track of all active file operations.

File Control Block (FCB): Stores file details such as:

1. File Descriptor (Unique identifier for an open file)
2. File Name & Path
3. Access Mode (Read, Write, Execute)
4. Pointer to File Location in Memory/Disk

Example:
If a process opens data.txt, the OS stores its details in the open file table, ensuring correct access and modifications.

 List of Open Devices in an OS

Similar to open files, the OS keeps a list of open devices to manage hardware interactions.

Device Table Stores:

1. Device Name & Type (Keyboard, Printer, USB, etc.)
2. Device Driver Information
3. Current Process Using the Device
4. Status of the Device (Active/Idle)

Example:
If a process is using a printer, the OS tracks it in the open device list to prevent conflicts between multiple processes.

 Summary:

General Purpose Registers store temporary data for CPU operations.
List of Open Files tracks active file usage for efficient data management.
List of Open Devices ensures proper hardware access and control.

Would you like more details on register functions, file systems, or device management?

Day 01Part 13 – General purpose register list of open files and list of open devices.

PART I: BIDDING PROCEDURE TENDER “AGAFC-01”

Standardized Object Classes Definitions

Here’s a well-organized explanation for Day 01 – Part 13 of your Operating System study:

Day 01 – Part 13: General Purpose Registers, List of Open Files & Open Devices (OS Concepts)

1. General Purpose Registers

Definition:
General Purpose Registers (GPRs) are small, fast memory units inside the CPU used to temporarily store data and perform operations during instruction execution.

Common General Purpose Registers:

(Names vary by architecture; here’s an x86 and general view)

Used by CPU during context switching, interrupt handling, and execution of instructions.

2. List of Open Files

Definition:
This is a system-maintained list of all files that are currently opened by processes.

Components:

• Each process has a File Descriptor Table.
• The OS maintains a global Open File Table.
• Each entry contains:
  • File descriptor number
  • File pointer (current read/write position)
  • File access mode (read/write)
  • File control block (metadata)

Purpose:

• Track who is using what file.
• Manage access rights.
• Ensure concurrent access control.

Example: Linux maintains this using /proc/[pid]/fd/

3. List of Open Devices

Definition:
The list of open devices refers to I/O devices currently being used by active processes.

Includes:

• Printers
• USB drives
• Keyboard/mouse
• Network interfaces
• Display devices

What is tracked:

• Device ID / type
• Status (open, busy, available)
• Which process is using it
• I/O mode (read/write)
• Buffer and driver info

Managed Through:

• Device Tables
• I/O Control Blocks
• Driver queues

Summary Table

Would you like a diagram or memory structure illustration to visually explain these OS components?

Day 01Part 13 – General purpose register list of open files and list of open devices.

OPERATING SYSTEMS (R13 III B.TECH I SEM) UNIT – I