Operating System?

Question

can i make o.s. in vb.net????
if yes, what you think about the loading the program at first time approach?
if you know any resource please let me know ....

Answer 1

I don't think so, because visual basic's output/input is dependent on the windows OS. (it makes calls to it to output visuals/files).

Windows is based on the C++ language, which allows developers to add their own libraries, and it doesn't depend on the windows OS for its output/input calls. It makes a call to a library that then makes the windows calls which can be omitted from the program.

Answer 2

You can't, you need a lower level language to write an OS. Consider using c / c++ and assembly to write one.

Answer 3

You cant. To write a OS, you should start writing the program in assembly.

Answer 4

gosh are u freakin out.. 'll need gr8 softwares for that i gues n a lota money n who wil buy urs when windows, mac, linux, etc are there

Answer 5

you want to make an operating system.....?? if yes....it takes money and a lot of skill for one person to create it.

Answer 6

An operating system (OS) is a computer program that manages the hardware and software resources of a computer. At the foundation of all system software, the OS performs basic tasks such as controlling and allocating memory, prioritizing system requests, controlling input and output devices, facilitating networking, and managing files. It also may provide a graphical user interface for higher level functions.

Introduction
A typical vision of a computer architecture as a series of abstraction layers: hardware, firmware, assembler, kernel, operating system and applications (see also Tanenbaum 79).
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A typical vision of a computer architecture as a series of abstraction layers: hardware, firmware, assembler, kernel, operating system and applications (see also Tanenbaum 79).

Modern general-purpose computers, including personal computers and mainframes, have an operating system (a general purpose operating system) to run other programs, such as application software. Examples of operating systems for personal computers include Microsoft Windows, GNU/Linux, and Mac OS.

The lowest level of any operating system is its kernel. This is the first layer of software loaded into memory when a system boots or starts up. The kernel provides access to various common core services to all other system and application programs. These services include, but are not limited to: task scheduling, memory management, disk access, and access to hardware devices.
An example of MS-DOS's command-line interface, this one showing that the current directory is the root of drive C
Enlarge
An example of MS-DOS's command-line interface, this one showing that the current directory is the root of drive C

Apart from the kernel, an operating system is often distributed with system software that manages a graphical user interface (although Windows and Macintosh have integrated these programs into the operating system), as well as utility programs for tasks such as managing files and configuring the operating system. Oftentimes distributed with operating systems are application software that does not directly relate to the operating system's core function, but which the operating system distributor finds advantageous to supply with the operating system.

Delineating between the operating system and application software is not a completely precise activity, and is occasionally subject to controversy. From commercial or legal points of view, the delineation can depend on the contexts of the interests involved. For example, one of the key questions in the United States v. Microsoft antitrust trial was whether Microsoft's web browser was part of its operating system, or whether it was a separable piece of application software.

Like the term "operating system" itself, the question of what exactly the "kernel" should manage is subject to some controversy, with debates over whether things like file systems should be included in the kernel. Various camps advocate microkernels, monolithic kernels, and so on.

Operating systems are used on most, but not all, computer systems. The simplest computers, including the smallest embedded systems and many of the first computers did not have operating systems. Instead, they relied on the application programs to manage the minimal hardware themselves, perhaps with the aid of libraries developed for the purpose. Commercially-supplied operating systems are present on virtually all modern devices described as computers, from personal computers to mainframes, as well as mobile computers such as PDAs and mobile phones.

[edit] Services

[edit] Process management

Every action on a computer, be it background services or applications, is run inside a process. As long as a von Neumann architecture is used to build computers, only one process per CPU can be run at a time. Older OS such as MS-DOS did not attempt any artifacts to bypass this limit and in fact only one process could be run under them (although DOS itself featured TSR as a very partial and not too easy to use solution). Modern operating systems are able to simulate execution of many processes at once (multi-tasking) even under a single CPU. Process management is an operating system's way of dealing with running multiple processes. Since most computers contain one processor with one core, multi-tasking is accomplished by simply switching processes quickly. As a user runs more processes, all timeshares become smaller. On many systems, this can eventually lead to problems such as skipping of audio or jittery mouse movement (this is called thrashing, a state in which OS related activity becomes the only thing a computer does). Process management involves the computation and distribution of "timeshares". Most operating systems allow a process to be assigned a process priority which impacts its timeshare. Interactive operating systems also employ some level of feedback in which the task with which the user is working receives a priority boost.

[edit] Memory management

According to Parkinson's law "Programs expand to fill the memory available to hold them". Thus the programmers like a memory of infinite size and infinite speed. Nowadays most of the computer's memory is arranged in a hierarchical manner, starting from fastest registers, cache, RAM and disk storage. The memory manager in an OS coordinates the memories by tracking which one is available, which is to be allocated or deallocated and how to swap between the main memory and secondary memories. This activity which is usually referred to as virtual memory management greatly increases the amount of memory available for a process (typically 4GB, even if the physical RAM available is less). This however comes at a speed penalty which is usually low, but can become very high in extreme cases and, again, lead to thrashing.

Another important part of memory management activity is managing virtual addresses, with help from the CPU. If multiple processes are in memory at once, they must be prevented from interfering with each other's memory (unless there is an explicit request to share for a limited amount of memory and in controlled ways). This is achieved by having separate address spaces. Each process in fact sees the whole virtual address space (typically, from address 0 up to the maximum size of virtual memory) as uniquely assigned to it (ignoring the fact that some areas are OS reserved). What actually happens is that the CPU stores some tables to match virtual addresses to physical addresses.

By creating a separate address space for each process, it is also simple for the operating system to free all of the memory that was used by a particular process. If a process does not free memory, this is unimportant once the process ends and the memory is all released.

[edit] Disk and file systems

Operating systems have a variety of native file systems. Linux has a greater range of native file systems, those being: ext2, ext3, ReiserFS, Reiser4, GFS, GFS2, OCFS, OCFS2, NILFS and Google File System. Linux also has full support for XFS and JFS, along with the FAT file systems, and NTFS. Windows on the other hand has limited file system support which only includes: FAT12, FAT16, FAT32, and NTFS. The NTFS file system is the most efficient and reliable of the four Windows systems. All the FAT systems are older than NTFS and have limitations on the partition and file size that can cause a variety of problems.

For most of the above file systems there are two ways it can be allocated. Each system can be journaled or non-journaled. Journaled being the safer alternative under the circumstances of a system recovery. If a system comes to an abrupt stop, in a system crash scenario, the non-journaled system will need to undergo an examination from the system check utilities where as the journaled file systems recovery is automatic. Microsoft's NTFS is journaled along with most Linux file systems, except ext2, but including ext3, reiserfs and JFS.

Every file system is made up of similar directories and subdirectories. Along with the operating systems file system similarities there are the subtle differences. Microsoft separates its directories with a back slash and its file names aren't case sensitive whereas Unix-derived operating systems (including Linux) use the forward slash and their file names generally are case sensitive.

[edit] Networking

Most current operating systems are capable of using the now-universal TCP/IP networking protocols. This means that one system can appear on a network of the other and share resources such as files, printers, and scanners.

Many operating systems also support one or more vendor-specific legacy networking protocols as well, for example, SNA on IBM systems, DECnet on systems from Digital Equipment Corporation, and Microsoft-specific protocols on Windows. Specific protocols for specific tasks may also be supported such as NFS for file access.

[edit] Security

Many operating systems include some level of security. Security is based on the two ideas that:

* The operating system provides access to a number of resources, directly or indirectly, such as files on a local disk, privileged system calls, personal information about users, and the services offered by the programs running on the system;
* The operating system is capable of distinguishing between some requestors of these resources who are authorized (allowed) to access the resource, and others who are not authorized (forbidden). While some systems may simply distinguish between "privileged" and "non-privileged", systems commonly have a form of requestor identity, such as a user name. Requestors in turn divide into two categories:

* Internal security: an already running program. On some systems, a program once it is running has no limitations, but commonly the program has an identity which it keeps and is used to check all of its requests for resources.
* External security: a new request from outside the computer, such as a login at a connected console or some kind of network connection. To establish identity there may be a process of authentication. Often a username must be quoted, and each username may have a password. Other methods of authentication such as magnetic cards or biometric data might be used instead. In some cases, especially connections from the network, resources may be accessed with no authentication at all.

In addition to the allow/disallow model of security, a system with a high level of security will also offer auditing options. These would allow tracking of requests for access to resources (such as "who has been reading this file"?)

Security of operating systems has long been a concern because of highly sensitive data held on computers, both of a commercial and military nature. The United States Government Department of Defense (DoD) created the Trusted Computer System Evaluation Criteria (TCSEC), which is a standard that sets basic requirements for assessing the effectiveness of security. This became of vital important to operating system makers, because the TCSEC was used to evaluate, classify and select computer systems being considered for the processing, storage and retrieval of sensitive or classified information.

Answer 7

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