OS ext

Question 1

Monolithic system

Answer 1

The operating system is written as a collection of procedures, linked together into a single large executable binary program.

Question 2

How does the monolithic system invoke the OS structure

Answer 2

A main program that invokes the requested service procedure.
A set of service procedures that carry out the system calls.
A set of utility procedures that help the service procedures.

Question 3

Layered systems layers

Answer 3

0 – dealt with allocation of the processor

1 – memory management

2- process communication

3- I/O management

4- User programs

5- System Operator

Question 4

Microkernels

Answer 4

• implementation of layered system approach with certain kernel user boundaries
• minimum amount of software required to provide mechanisms to implement an OS.

Question 5

Hybrid Kernel

Answer 5

runs some services in the kernel space
to reduce the performance overhead of a traditional microkernel,
while still running kernel code as servers in the user space.

Question 6

Why is it important for an operating system to have kernel mode and user mode?

Answer 6

1. Kernel mode allows access to all machine instructions and I/O devices.
2. In user mode many sensitive instructions are prohibited.
3. The two modes allow the OS to encapsulate user programs.

Question 7

Threads

Answer 7

• A thread is essentially a piece of instruction which is managed by the operating system.
• They perform activities around the process rather than running the process itself

Question 8

Starting up chrome

Answer 8

1. Ram holds program code and data
2. Instruction bytes are copied from storage to RAM
3. CPU is directed to start running at the first instruction
4. Chrome is launched

Question 9

Virtual Machine Uses

Answer 9

Game emulators
Dual Booting
Disaster Recovery
cloud tech
Containers

Question 10

BIOS proper def

Answer 10

• The BIOS contains low-level I/O instructions,
• Loads os onto main memory then stores config info for peripherals (keyboard etc.)
• performs system integrity checks

Question 11

Race conditions

Answer 11

When it comes to processes and threads a race condition can cause bugs.
This occurs when a process or a thread depend on some shared state and they are not mutually exclusive.

Question 12

Mutual Exclusion

Answer 12

Mutual exclusion is the requirement that one thread of execution never enters a critical section while another thread happening at the same time of execution is already using the critical section.

Question 13

Stack

Answer 13

• Stack is a stack of information/nodes stacked one over another with the highest address node placed at top
• When an information is added, memory is incremented by 1 and when an information is removed, memory is reduced by 1.
• Follows last in first out(like a stack of plates)

Question 14

2 major functions of stack

Answer 14

a) Push - Adding information to the stack

b) Pop - Removing information from the stack

Question 15

GRUB proper def

Answer 15

• GRUB needs to understand the file systems,
• the kernels executing commands
• works like a transfer step on passing control to the operating systems kernel software from the MBR.