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DOSBox is an emulator that allows you to run old MS-DOS programs, games, and applications on modern systems (Windows, macOS, and Linux).
Typology: Summaries
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Aim : To study DOS operating system and its commands. x86 Architecture : The x86 architecture is family of instruction set developed by Intel based on the 8086 CPU. It has been used in many personal computers since 1970s. Important Features of x86 mode : 1.16-bit Architecture: In x86 Mode, the CPU has access to only 16 bit data bus. This means that size of registers and data are limited to 16 bits. The registers that can be accessed are only AX,BX,CX and DX. The maximum value that can be held in a register will be 2^16 – 1 (65,535). 2.Memory Addressing: In x86 Mode, the CPU can address a maximum of 1 MB (megabyte) of memory. This is because x86 mode has only 20-bit address bus. Memory in x86 Mode is divided into 4 segments(Data Segment, Code Segment, Extra Segment and Stack Segment), and each segment is 64 KB in size. A segment register holds the base address, and an offset register specifies the exact location within that segment. 3.No Memory Protection: x86 Mode is also known as Real Mode as there is no memory protection. This means that any program running in x86 Mode can access any part of the memory. This makes system vulnerable to crashes and errors if a program overwrites important data.
Block Diagram of 8086 DOS(Disk Operating System) : DOS (Disk Operating System) is an early operating system primarily used in personal computers before the rise of graphical user interfaces like Windows. Important Features: 1.Command-Line Interface : DOS operates through a command-line interface , where users type commands to perform tasks like file management and running programs. 2.Single-User and Single-Tasking : DOS is a single-tasking operating system, meaning it can run only one program at a time. 3.Low Memory Requirements : DOS is requires very little memory (1MB)to operate, making it suitable for early personal computers with limited hardware resources.