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Operating System
The most important software that runs on a computer which manages computer system hardware and software, memory, and processes of the software.
It is a group of programs that allow a user to control and communicate with a computer.
Software
Hardware
Two parts of a Computer System
Software
The intangible part of the computer system (e.g., programs, application).
Hardware
The tangible part of the computer system (e.g., physical machine and electronic).
True
True or False. Operating system is a software part of the computer system.
Microsoft Windows
macOS
Linux
Android
iOS
Commonly used operating systems
Memory Manager
Processor Manager
Device Manager
File Manager
Network Manager
5 Essential Managers of Operating System
Manager
It monitors its resources continuously. It enforces the policies that determine who gets what, when and how much. It allocates and deallocates the resource when appropriate.
Mainframe
Minicomputer
Supercomputer
Microcomputer
Server
5 History of Machine Hardware
Mainframe
It is a large machine – in size and in internal memory capacity.
IBM 360 (1964)
a classic example of an early mainframe
IBM 360 model 30
It requires an air-conditioned room about 18 feet square. Its CPU was 5 feet high and 6 feet wide. Its internal memory has 64K.
$200 000
How much did IBM 360 model 30 cost?
Minicomputer
It was developed to meet the needs of smaller institutions. It is smaller in size and memory capacity. It is cheaper.
Midrange Computers
Minicomputer is also iknown as _____.
Digital Equipment Corp. (early 1970)
example of minicomputer that only costs less than $18000
Supercomputer
It is a massive machine. It was developed primarily for government applications. It is for military operations and weather forecasting. Its uses include: scientific research and customer support or product development.
Cray supercomputer
example of supercomputer that has 6 to 1000 processors
microcomputer
It is developed for single users in the laet 1970s. Its physical size was smaller than the minicomputers.
Microcomputers by Tandy Corporation and Apple Computer, Inc.
example of microcomputer
- Single-user status
Microcomputer’s distinguishing characteristic
Workstations
It is the most poweful microcomputers. It is developed for commercial, educational, and government enterprises. It is networked together.
It supports engineering and technical users.
Servers
These are powerful computers that provide specialized services to other computers on client/server networks.
Print servers
Internet servers
Mail servers
examples of servers
Batch System
Interactive
Real-time
Hybrid
Embedded
Five types/categories of Operating System
Batch systems
It dates from the earliest computers, when they relied on stacks of punched cards or reels of magnetic tape for input.
Jobs were entered by assembling the cards into a deck and running the entire deck of cards through a card reader as a group—a batch.
Throughput
the number of jobs completed in a given amount of time
Throughput
The efficiency of a batch system is measured in _________.
Interactive Systems
It gives a faster turnaround than batch system, but are slower than real-time systems. They were introduced to satisfy the demands of users who needed fast turnaround when debugging their programs.
It required the development of time-sharing software. It provides immediate feedback to the user and response time can be measured in fractions of a second.
turnaround
the time it took for the jobs/processes to do their tasks
millisecond
fractions of a second.
Real-time systems
It is used in time-critical environments where reliability is key and data must be processed within a strict time limit. They must meet the deadline or risk significant consequences.
They must be 100% responsive, 100% of the time.
Hard real-time systems
Soft real-time systems
Two Types of Real-Time Systems
Hard real-time systems
They risk total system failure if the predicted time deadline is missed.
Soft real-time systems
They suffer performance degradation, but not total system failure, as a consequence of a missed deadline.
Hybrid Systems
It is a combination of batch and interactive. Its users can access the system and get fast responses. It accepts and runs batch programs in the background when the interactive load is light.
It takes advantage of the free time between high-demand usage of the system and low-demand times
Embedded systems
Computers placed inside other products to add features and capabilities.
This permits the designers to make the operating system more efficient and take advantage of the computer’s limited resources, such as memory, to their maximum.
False
True or False. Each embedded system is designed to perform a set of specific programs, which are interchangeable among systems.
1940s: first generation
Year of OS Dev. There is no operating system. Computers are based on vacuum tube technology. All instructions are performed manually. It has poor machine utilization. Computers are the size of the classrooms.
Dr. Grace Hopper
Who discovered a bug on Harvard’s Mark I in 1945?
Moth
What kind of bug is discovered on Harvard’s Mark I in 1945?
1950s: second generation
Year of OS Dev. It focused on the cost-effectiveness of the system. It is developed for government and business researchers. Computers were expensive (IBM 360). There are expensive time lags between CPU and I/O devices.
Computer operators were hired to facilitate machine operation
Concept of job scheduling
Two widely adopted improvements in 1950s
Job Scheduling
It is the concept of grouping together programs with similar requirements. It introduced the need for control cards.
1960s: third generation
Year of OS Dev. It has faster CPUs. Speeds caused problems when they interacted with slower I/O devices. The concept of multiprogramming was introduced.
multiprogramming
In 1960s, It introduced the concept of loading many programs at one time and sharing the attention of a single CPU.
interrupt
The most common mechanism for implementing multiprogramming was the introduction of the concept of the ___________.
Active multiprogramming
Passive multiprogramming
Two types of multiprogramming
Active multiprogramming
It occurs when the operating system interrupts a job process
Passive multiprogramming
The operating system didn’t control the interrupts but waited for each job to end an execution sequence .
1970s
Year of OS Dev. There are main memory physical capacity limitations (multiprogramming increased CPU usage), which was solved by virtual memory. The database management software was introduved. The programs started using English-like words, modular structures, and standard operations
Database management software
It organized data in an integrated manner, minimized redundancy, and simplified updating and access of data
1980s
Year of OS Dev. Cost/performance ratio improvement of computer components. There are more flexible hardware, with logical functions built on easily replaceable circuit boards. Firmware and Multiprocessing were introduced.
Firmware
Introduced in 1970s, it indicates that a program is permanently held in read-only memory (ROM)
Multiprocessing
Introduced in 1970s, it means having more than one processor. More complex languages were designed to coordinate the activities of the multiple processors servicing a single job.
1990s
Year of OS Dev. Internet capability sparked the proliferation of networking capability. The WWW made the Internet accessible. It introduced a proliferation of multimedia applications demanding additional power, flexibility, and device compatibility for most operating systems
Tim Berners-Lee
In 1990s, who made the WWW?
World Wide Web
Meaning of WWW
2000s
Year of OS Dev. It supports: multimedia application, Internet and Web access, and Client/Server computing. It increased CPU speed, has high-speed network attachments, and increased number of storage devices. It introduces virtualization.
Object-oriented design
The way the components of the OS are programmed and organized, specifically the use of ________, and and the reorganization of the operating system’s nucleus.
kernel
It is the operating system’s nucleus. It is a part of the OS that resides in memory at all times, performs the most essential operating system tasks, and is protected by hardware from user tampering.
Early OS loaded its entirety into main memory.
Object-oriented OS load only critical elements into main mamory and call other objects as needed.
Difference between Early OS and Object-Oriented OS
Memory Management
It refers to how computers manage their main memory.
It keeps the resources that the CPUs can immediately access.
Access Memory
Random Access Memory (RAM)
Core Memory
Primary Storage
4 Types of Memory Manager
Single-user contiguous scheme
Fixed partitions
Dynamic partitions
Relocatable dynamic partitions
4 Early Memory Allocation Schemes
Single-user Contiguous Scheme
This early moment allocation scheme requires a minimal amount of work done by the operating system's memory manager.
Program was loaded in its entirety into memory and allocated as much contiguous space in memory as needed.
False
True or False. Single-user contiguous scheme permits multiprogramming.
Sequentially
In single-user contiguous scheme, jobs are processed _______ in a single-user system.
Static Partitions
Fixed partition is also called as _______.
Fixed Partition
This early memory allocation scheme is where the main memory is partitioned (equal or unequal), with one job in each partition.
shut down, reconfigured, and restarted
In fixed partition, its sizes remain static unless and until the computer system is _______.
Protection of the job’s memory space
Matching job size with partition size
The Two Requirements of Fixed partition
True
True or False. Fixed partition permits multiprogramming.
Dynamic Partition
This early memory allocation scheme has its memory divided into variable-sized partitions based on the size of the process
First-Fit Memory Allocation
Best-Fit Memory Allocation
Two job allocation methods of Dynamic Partition
First-Fit Memory Allocation
A job allocation method of dynamic partition where the first partition fits the requirements.
Best-Fit Memory Allocation
A job allocation methods of dynamic partition where the smallest partition fits the requirements.
Internal fragmentation is reduced, but not eliminated.
Speed
Space or Speed. The major aspect of first-fit memory allocation.
Space
Space or Speed. The major aspect of best-fit memory allocation.
Deallocation
It is the process of freeing an allocated memory space.
Resets the status of the memory block to “free”
Deallocation method for fixed-partition system
Case 1: Joining Two Free Blocks
Case 2: Joining Three Free Blocks
Case 3: Deallocating an Isolated Block
Deallocation method for dynamic partition system
Relocatable Dynamic Partitions
Memory Manager relocates programs to gather together all of the empty blocks and compact them to make one block of memory, large enough to accommodate some or all of the jobs waiting to get in
Garbage collection or Defragmentation
The compaction of memory, sometimes referred to as ___________, is performed by the operating system to reclaim fragmented sections of the memory space
Virtual Memory
A storage method that gives the user the impression that their main memory is quite large, this approach allows them to load larger size programs than the primary memory that is accessible.
Enhanced level of multiprogramming which will then increase CPU consumption
Effect of using virtual memory
Paging
It is a storage mechanism used to retrieve processes.
Pages
In paging, the main memory is divided into small blocks called ______.
Equal
It is very important to have pages and frames which are of _______ sizes which are very useful for mapping and complete utilization of memory.
Mapping
Complete utilization of memory
Pages and frames which are of equal sizes are very useful for _____ and ________.
Demand Paging
A condition occurred in the virtual memory where the pages of the processes are stored in the secondary memory and the page is brought to the main memory when required.
It is the process of calling the pages to main memory from secondary memory upon demand
Page Replacement Algorithms
In demand paging, the pages are brought to the main memory when required by the _______.
First In First Out (FIFO) Replacement Algorithm
Least Recently Used (LRU) Replacement Algorithm
2 Page Replacement Algorithms
Page Fault
It occurs when a program tries to access a memory page that is not present in the memory.
Page Hit
It occurs when a program tries to access a memory page that is already present in the memory.
First In First Out (FIFO) Algorithm
This is the simplest page replacement algorithm.
The policy is to remove the pages that have been in memory the longest.
Least Recently Used (LRU) Replacement Algorithm
In this algorithm, the page will be replaced which is least recently used.
Page replacement policy swaps out the pages that show the least amount of recent activity, figuring that these pages are the least likely to be used again in the immediate future.