Diving into the History of Operating Systems
An operating system is a software program that manages and controls various devices, from smartphones to supercomputers. Its purpose is to serve as a bridge between the user and the computer hardware, without requiring a deep understanding of coding.
Features of an Operating System:
An operating system has several key features, including:
- Protected and supervisor mode
- Program execution
- Manipulation of the file system
- Handling I/O operations
- Error handling
- Resource allocation
- Information and resource protection
Conclusion
In conclusion, an operating system is a crucial component of any computing device. It allows users to interact with and control hardware without needing to understand complex coding languages. The system handles key functions such as program execution, file manipulation, and resource allocation.
Additional Resources
To learn more about operating systems, check out the following resources:
- Operating Systems: Three Easy Pieces (book)
- Operating System Concepts (book)
- OS/161 (educational operating system project)
- Linux (open source operating system)
A Brief History and Functions of Operating Systems
Operating systems (OS) have come a long way from the first OS built in 1956 to manage tape storage. Bell Labs created UNIX in the 70s, followed by Apple DOS 3.3 in 1977, and MS-DOS by Microsoft in 1981. The most recent version of Windows for PCs and tablets is Windows 11, version 21H2.
The OS has several functions, including processor management to manage resource allocation efficiently, file management to control all files with various extensions, booting to configure hardware and load the OS, device management to track connected devices, error detection, and coordinating software and users.
The OS consists of two components: the shell and the kernel. The shell is the interface that connects the kernel and the user, allowing users to communicate with the kernel by running various programs. The kernel is the heart of the OS, tracking the hardware and computer’s operations and serving as a bridge between users and system resources.
Important Features of an Operating System
# Define important features of an operating system
features = ["Memory Management", "Multitasking", "Process Management", "Device Management"]
# Print the features
for feature in features:
print(feature)
An operating system has several important features that make it essential for the functioning of a computer. These features include memory management, which ensures that memory is allocated and deallocated efficiently. Multitasking allows the system to run multiple programs simultaneously. Process management controls how processes are created and terminated. Device management controls the interaction between the computer hardware and the operating system.
Protected and Supervisor Mode in CPUs
In modern CPUs, there are two modes: protected mode and supervisor mode, enabling OS kernels to regulate and change specific CPU functions. When a computer turns on, it starts in supervisor mode. The BIOS, bootloader, and OS are the first programs to initialize, with full hardware access. Programs in protected mode have limited access to CPU instructions, and only an interrupt can return control to the kernel. This ensures OS control over hardware and memory. Supervisor mode is utilized by the OS for low-level activities that require complete hardware access.
Code:
“`python
# Define constants for protected and supervisor mode
PROTECTED_MODE = 0
SUPERVISOR_MODE = 1
# Set CPU to start in supervisor mode
cpu_mode = SUPERVISOR_MODE
# Function to switch between protected and supervisor mode
def context_switch(new_mode):
global cpu_mode
cpu_mode = new_mode
# perform other context switch operations
# Demo a switch from protected to supervisor mode
context_switch(SUPERVISOR_MODE)
“`
Image: Context switching between user mode and supervisor mode
Program Execution in Operating Systems
Operating systems have a broad range of tasks; from user applications to system programs like printers, name servers, and file servers. These tasks are divided into a series of steps wherein a process is executed. The execution context comprises the code to execute, data to manipulate, registers, and OS resources in use. Managing programs is a significant activity of operating systems, which includes the following tasks:
* Loading a program into memory upon execution of the command
* Running and handling program execution
* Providing a mechanism for process synchronization
* Providing a mechanism for process communication
* Providing a mechanism for deadlock handling.
// code goes here
File System Management
A file is a collection of data stored on a computer’s secondary storage like a magnetic tape or disc. In an operating system, the file system manages these files, providing a way to store data and access file contents, including applications.
Some OS, like Ubuntu, treats everything as a file. File management activities include giving programs permission to read/write files, handling read-write permissions on files, creating/deleting folders, and interfaces for creating file system backups.
Handling Input/Output Operations in Operating Systems
In an Operating System, managing various input/output devices is crucial. It includes handling of mice, keyboards, touchpads, disc drives, USB devices, display adapters, network connections, and printers. The Operating System must accept an application’s I/O request, forward it to the respective physical device, retrieve the device’s response, and deliver it back to the application.
Major activities performed by the Operating System to handle I/O operations are:
– Managing the connection between the user and the device drivers.
– Reading the data-in register for input.
– Writing the data-out register for output.
– Using bits in the status register that can read the host.
– Writing the control register to change the device’s mode or initiate a command.
Code:
“` python
# Function to handle Input/Output operations in Operating Systems
def io_operations():
# Connection management between user and device drivers
conn_man = ConnectionManager()
conn_man.manage()
# Reading data-in register for input
data_in = InputData()
input_data = data_in.read_data()
# Writing data-out register for output
data_out = OutputData()
output_data = data_out.write_data()
# Reading status register
status = StatusRegister()
status_bits = status.read_bits()
# Writing control register to initiate command or change device mode
control = ControlRegister()
control.write_command()
“`
Error Handling
Errors can occur at any time and in any location in an operating system. These errors can be caused by bugs in CPU, I/O devices or memory hardware and can cause a variety of problems. The following are key error-handling activities that an operating system performs:
* The operating system constantly monitors for issues such as power failures, connection failures, and paper shortages in printers.
* In the worst-case scenario, the application’s error handling procedures force the user to log out, and the system shuts down.
// Code for monitoring errors
while (systemOn) {
if (powerFailure) {
alertUser("Power failure detected.");
shutdownSystem();
}
if (connectionFailure) {
alertUser("Connection failure detected.");
reconnect();
}
if (paperShortage) {
alertUser("Printer is out of paper.");
refillPaper();
}
}
By continually monitoring and handling errors, the operating system ensures that the system remains stable and functional for the user.
Resource Allocation
In a computer system, the Operating System allocates resources when software requests them and de-allocates when the program ends. Resources have restricted availability, including main memory, CPU cycles, and file storage. Each user or job in multi-user or multi-tasking contexts must be allotted these resources.
Protecting Information and Resources
In order to prevent loss of data due to human error, malicious programs, or system vulnerabilities, it is imperative to safeguard all data, applications, and the operating system itself. To maintain system integrity, availability, and confidentiality, following measures should be taken:
1. AUTHENTICATION: Operating systems use authentication to ensure that only authorized personnel access programs.
2. BACKUP AND RESTORE: The operating system provides software for creating and restoring data backups. Keeping these files off-site is the safest option.
Evolution of Operating Systems
In the 1950s, computers could only run one application at a time. Operating systems play a crucial role in controlling memory allocation, detecting input from external devices, and sending output to computer displays. With time, libraries of software packages were developed, forming the basis of modern operating systems. Today, most operating systems feature graphical user interfaces, accepting input from pointing devices, such as a mouse or stylus. Operating systems are necessary software that controls computer hardware, providing public services to applications. They allow applications to use the public library without worrying about the individual. The most commonly used operating systems for IBM-compatible personal computers are Microsoft Windows, Linux, and Mac OS X.
Additional Resources
For more information and practice opportunities, visit the following resources:
