Lecture 6: General Review and Questions

1. Key Concepts Review

• Bootstrap Program: Initializes hardware and loads the OS during startup, stored in ROM.
• Kernel: The only program that runs all the time; the core of the OS.
• Process: A unit of work within the system; an active program.
• Multiprocessor System: A system using multiple CPUs sharing one memory.
• Registers: The smallest, fastest type of memory used to store temporary data inside the CPU.
• Kernel Mode: The CPU mode that allows full hardware access and executes privileged instructions.
• Scheduling: The method by which the OS decides which process gets the CPU next.
• RAM: Volatile memory that loses its contents when power is turned off.
• Cache: A temporary storage area that keeps frequently used data for faster access.

2. Common Misconceptions (Correction of Mistakes)

• Mistake: The operating system runs in User mode to access all hardware.
  • Correction: It runs in Kernel Mode for full hardware access.
• Mistake: ROM is volatile memory that loses data when power is off.
  • Correction: RAM is volatile. ROM is non-volatile.
• Mistake: A process and a program are the same thing.
  • Correction: A Program is passive; a Process is active (program in execution).
• Mistake: In symmetric multiprocessing, one CPU is the master and controls all others.
  • Correction: This describes Asymmetric multiprocessing.
• Mistake: Caching makes data access slower by adding extra steps.
  • Correction: Caching makes data access faster.

3. Core Function Explanations

• Why Dual-Mode Operation? To protect the system by separating user code (limited access) from kernel code (full access).
• DMA Benefit: It transfers data directly between memory and device without CPU involvement, improving performance.
• Multiprogramming Benefit: It ensures the CPU always has a process to run while others wait for I/O, improving CPU utilization.

Audio Summary