Operating System Concepts - Computer System Structure Quiz

Computer System Structure

• A computer system can be divided into four components: hardware, operating system, application programs, and users.
• Hardware provides basic computing resources such as CPU, memory, and I/O devices.
• Operating system controls and coordinates the use of hardware among various applications and users.
• Application programs define how system resources are used to solve computing problems for users.
• Users can be people, machines, or other computers.

Bootstrap Program

• A bootstrap program is loaded at power-up or reboot.
• It is typically stored in ROM or EPROM, known as firmware.
• The bootstrap program initializes all aspects of the system and loads the operating system kernel.

Firmware

• Firmware is a specific type of software that acts as an intermediary between software and hardware.

Computer-System Operation

• One or more CPUs and device controllers connect through a common bus providing access to shared memory.
• The CPU and devices compete for memory cycles.
• I/O devices and the CPU can execute concurrently.
• Each device controller is in charge of a particular device type and has a local buffer.
• The CPU moves data from/to main memory to/from local buffers.
• I/O is from the device to the local buffer of the controller.
• The device controller informs the CPU that it has finished its operation by causing an interrupt.

Interrupts

• Interrupts transfer control to the interrupt service routine through the interrupt vector.
• The interrupt architecture must save the address of the interrupted instruction.
• A trap or exception is a software-generated interrupt caused by an error or user request.

Operating System Goals

• Execute user programs and make solving user problems easier.
• Make the computer system convenient to use.
• Use the computer hardware in an efficient manner.

Operating System Definition

• An operating system is a resource allocator that manages all resources and decides between conflicting requests for efficient and fair resource use.
• An operating system is a control program that controls the execution of programs to prevent errors and improper use of the computer.