Design Principles Microsoft's design goals for Windows XP include security, reliability, Windows and POSIX application compatibility, high performance, extensibility, portability, and international support.
29 Dec 2017
24 Dec 2017
Contiguous memory allocation
The main memory must accommodate both the operating system and the various user processes. We therefore need to allocate the parts of the main memory in the most efficient way possible. This section explains one common method, contiguous memory allocation.
24 Dec 2017
Semaphore In Operation System
The various hardware-based solutions to the critical-section problem (using the TestAndSetC) and SwapO instructions) are complicated for application programmers to use. To overcome this difficulty, we can use a synchronization tool called a semaphore. A semaphore S is an integer variable that, apart...
24 Dec 2017
Critical Section problems
The critical-section problem is to design a protocol that the processes can use to cooperate. Each process must request permission to enter its critical section. The section of code implementing this request is the entry section. The critical section may be followed by an exit section. The remaining...
24 Dec 2017
Multithreading Models
Our discussion so far has treated threads in a generic sense. However, support for threads may be provided either at the user level, for user threads, or by the kernel, for kernel threads. User threads are supported above the kernel and are managed without kernel support, whereas kernel threads are ...
24 Dec 2017
Threads overview
A thread is a basic unit of CPU utilization; it comprises a thread ID, a program counter, a register set, and a stack. It shares with other threads belonging to the same process its code section, data section, and other operating-system resources, such as open files and signals. A traditional (or h...
25 Dec 2017
Monitors
Although semaphores provide a convenient and effective mechanism for process synchronization, using them incorrectly can result in timing errors that are difficult to detect, since these errors happen only if some particular execution sequences take place and these sequences do not always occur. We ...
27 Dec 2017
Synchronization Hardware
Synchronization Hardware We have just described one software-based solution to the critical-section problem. In general, we can state that any solution to the critical-section problem requires a simple tool—a lock. Race conditions are prevented by requiring that critical regions be protected by lo...
30 Dec 2017
Algorithm Evaluation
Algorithm Evaluation How do we select a CPU scheduling algorithm for a particular system? there are many scheduling algorithms, each with its own parameters. As a result, selecting an algorithm can be difficult. The first problem is defining the criteria to be used in selecting an algorithm. As we...
01 Jan 2018
What is Special Purpose System?
Special-Purpose Systems The discussion thus far has focused on general-purpose computer systems that we are all familiar with. There are, however, different classes of computer systems whose functions are more limited and whose objective is to deal with limited computation domains.
25 Dec 2017
File sharing
In the previous sections, we explored the motivation for file sharing and some of the difficulties involved in allowing users to share files. Such file sharing is very desirable for users who want to collaborate and to reduce the effort required to achieve a computing goal. Therefore, user-oriented...
29 Dec 2017
Computer Security Classifications
Computer-Security Classifications The U.S. Department of Defense Trusted Computer System Evaluation Criteria specify four security classifications in systems: A, B, C, and D. This specification is widely used to determine the security of a facility and to model security solutions, so we explore it...
An operating system (OS) is system software that manages computer hardware and software resources and provides common services for computer programs.
01 Jan 2018
Programmer Interface
Programmer Interface The Win32 API is the fundamental interface to the capabilities of Windows XP. This section describes five main aspects of the Win32 API: access to kernel objects, sharing of objects between processes, process management, interprocess communication, and memory management.
26 Dec 2017
Swap Space Management
Swap-Space Use Swap space is used in various ways by different operating systems, depending on the memory-management algorithms in use. For instance, systems that implement swapping may use swap space to hold an entire process image, including the code and data segments. Paging systems may simply ...
30 Dec 2017
Application I/o Interface
Application I/O interface In this section, we discuss structuring techniques and interfaces for the operating system that enable I/O devices to be treated in a standard, uniform way. We explain, for instance, how an application can open a file on a disk without knowing what kind of disk it is and ...
01 Jan 2018
Atomic Transactions
Atomic Transactions The mutual exclusion of critical sections ensures that the critical sections are executed atomically. That is, if two critical sections are executed concurrently, the result is equivalent to their sequential execution in some unknown order. Although this property is useful in m...
31 Dec 2017
Access Matrix
Access Matrix Our model of protection can be viewed abstractly as a matrix, called an access matrix. The rows of the access matrix represent domains, and the columns represent objects. Each entry in the matrix consists of a set of access rights. Because the column defines objects explicitly, we ca...
26 Dec 2017
Stable Storage Implementation
Stable-Storage Implementation We introduced the write-ahead log, which requires the availability of stable storage. By definition, information residing in stable storage is never lost. To implement such storage, we need to replicate the needed information on multiple storage devices (usually disks...
30 Dec 2017
Transforming I/O Requests to Hardware Operations
Transforming I/O Requests to Hardware Operations Earlier, we described the handshaking between a device driver and a device controller, but we did not explain how the operating system connects an application request to a set of network wires or to a specific disk sector. Let's consider the example ...
01 Jan 2018
Threads-Summary
Summary A thread is a flow of control within a process. A multithreaded process contains several different flows of control within the same address space. The benefits of multithreading include increased responsiveness to the user, resource sharing within the process, economy, and the ability to t...
26 Dec 2017
Directory Implementation
Directory implementation The selection of directory-allocation and directory-management algorithms significantly affects the efficiency, performance, and reliability of the file system. In this section, we discuss the trade-offs involved in choosing one of these algorithms.
27 Dec 2017
Special purpose systems
Special-Purpose Systems The discussion thus far has focused on general-purpose computer systems that we are all familiar with. There are, however, different classes of computer systems whose functions are more limited and whose objective is to deal with limited computation domains.
27 Dec 2017
Thread scheduling
Thread Scheduling we introduced threads to the process model, distinguishing between user-level and kernel-level threads. On operating systems that support them, it is kernel-level threads—not processes—that are being scheduled by the operating system. User-level threads are managed by a thread li...
31 Aug 2017
Monolithic architecture - operating system
It is the oldest architecture of the operating system. We know that all the core software components of the operating system are collectively known as the kernel.
30 Dec 2017
An Example: AFS
Andrew is a distributed computing environment designed and implemented at Carnegie Mellon University. The Andrew file system (AFS) constitutes the underlying information-sharing mechanism among clients of the environment. The Transarc Corporation took over development of AFS, then was purchased by I...
28 Dec 2017
File System-Efficiency and Performance
Efficiency and Performance Now that we have discussed various block-allocation and directorymanagement options, we can further consider their effect on performance and efficient disk use. Disks tend to represent a major bottleneck in system performance, since they are the slowest main computer com...
29 Dec 2017
Revocation of Access Rights
Revocation of Access Rights In a dynamic protection system, we may sometimes need to revoke access rights to objects shared by different users
27 Dec 2017
Disk Attachment
Disk Attachment Computers access disk storage in two ways. One way is via I/O ports (or host-attached storage); this is common on small systems. The other way is via a remote host in a distributed file system; this is referred to as network-attached storage.
24 Dec 2017
Operations on Process
The processes in most systems can execute concurrently, and they may be created and deleted dynamically. Thus, these systems must provide a mechanism for process creation and termination. we explore the mechanisms involved in creating processes and illustrate process creation on UNIX and Windows sy...
