CS410 Official Handouts

Operating System is a software package which tells the computer how to function. It is essentially the body of the computer. Every general-purpose computer requires some type of operating system that tells the computer how to operate and how to utilize other software and hardware that is installed onto the computer.

GUI - Graphical User Interface operating systems are operating systems that have the capability of using a mouse and are graphical. To establish a point of reference, all computers must have an OS. The OS controls input and output; makes reasonable effort to control peripherals; and in short acts as the interface between you the user, the software, and the hardware.

Microsoft DOS (Disk Operating System) is a command line user interface. MS-DOS 1.0 was released in 1981 for IBM computers and the latest version of MS-DOS is MS-DOS

6. 22 released in 1994. While MS-DOS is not commonly used by itself today, it still can be accessed from Windows 95, Windows 98 or Windows ME by clicking Start / Run and typing command or CMD in Windows NT, 2000 or XP.

MS-DOS Programs

DOS programs generally expect themselves to be the only program running on the computer, so they will directly manipulate the hardware, such as writing to the disk or displaying graphics on the screen. They may also be dependent on timing, since the computer won't be doing anything else to slow them down. Many games fall into this category.

It ”owns” the system Provides direct device access Non-portability across machines Status polling No multitasking No multithreadingSingle path of execution DOS launches User Application; when done, control returned to DOS Assumes the current program is in total control of the hardware Supports the File Allocation Table (FAT) file system “Real-Mode” OS that is limited to the 8086 Address Space of 1 MB On November 10, 1983, Microsoft announced Microsoft Windows, an extension of the MS-DOS® operating system that would provide a graphical operating environment for PC users. Microsoft called Windows 1.0 a new software environment for developing and running applications that use bitmap displays and mouse pointing devices. With Windows, the graphical user interface (GUI) era at Microsoft had begun.

The release of Windows XP in 2001 marked a major milestone in the Windows desktop operating system family, by bringing together the two previously separate lines of Windows desktop operating systems.

Resource sharing Device independent programming Message driven operating system GDI (Graphics Device interface) Multitasking Multithreading

Difference · between · MS-DOS · and · Windows

In 32-bit windows programming, we are freed from the curse of 64k segments, far and near pointers, 16-bit integers and general limitations.

With this power, though, comes responsibility: we no longer have exclusive control over the machine. In fact, we don't have direct access to anything: no interrupts, no video ports, and no direct memory access.

Ultimately, the difference between these two types of programming term is who has control over the system. Moreover, by taking into account the message driven operating system, you would be better able to know what happens behind the scenes and how the system interacts with the internal and external messages.

Low level languages are more close to machine language or computer understandable language while the high level language are more close to human understandable language. Note that from one of the middle level language i.e. C / C++, two programming languages have emerged, MFC programming and Win32 API programming. Both of these programming languages have got their basis from C / C++.

MACHINE LANGUAGE

C / C ++ middle level language

WIN32 API MFC

OTHER ADVANCED LANUGUAGES ASSEMBLY LANGUAGE low level language