1.2.1. Systems Software

What is an operating system?

• A collection of programs that work together to provide an interface between the user and computer
• systems performing a task within a guaranteed time frame. They are used in systems were a response within a given time frame is critical
• Checking the CPU clock, memory and processor
• Testing for external memory devices

Identify functions of an operating system

• Memory management
• Resource management
• Utility software
• User interface
• Security

What are the similarities between paging and segmentation?

• used when RAM space is insufficient, can cause disk thrashing
• Uses equal-sized sections called pages
• Uses variable-sized, logical sections called segments

What are the differences between paging and segmentation?

• Paging: Uses equal-sized sections called pages
• Segmentation: Uses variable-sized, logical sections called segments
• Paging: Uses variable-sized, logical sections called segments
• Segmentation: Uses equal-sized sections called pages

Describe how virtual memory is used when there is not enough RAM.

• A section of the hard drive is used to act as RAM
• Sections of programs not currently being used are temporarily moved into virtual memory through paging
• This frees up memory for other programs in RAM
• A signal generated by software or hardware to indicate to the processor that a process needs attention.

What is an interrupt?

• A signal generated by software or hardware to indicate to the processor that a process needs attention.
• A section of the hard drive is used to act as RAM
• Sections of programs not currently being used are temporarily moved into virtual memory through paging
• This frees up memory for other programs in RAM

What are the advantages of using Multilevel Feedback Queues for scheduling?

• Services most urgent interrupts first
• frees up memory for other programs in RAM

What are the disadvantages of using Multilevel Feedback Queues for scheduling?

• Hard to implement
• Platform independent, portable
• Slower execution

Define a real-time operating system

• systems performing a task within a guaranteed time frame. They are used in systems were a response within a given time frame is critical
• Checking the CPU clock, memory and processor
• Testing for external memory devices
• A collection of programs that work together to provide an interface between the user and computer

Describe three functions of the BIOS.

• POST (Power-on self test) which ensures that all hardware is correctly connected and functional
• Checking the CPU clock, memory and processor
• Testing for external memory devices
• Enable the operating system to interact with hardware devices.