Windows Programming 2
Operating Systems History and overview
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.
About MS-DOS
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.
Features of DOS programming
• It ”owns” the system
• Provides direct device access
• Non-portability across machines
• Status polling
• No multitasking
• No multithreading- Single 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
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