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DOSBox is an emulator that allows you to run old MS-DOS programs, games, and applications, Summaries of Computer Science

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

2023/2024

Uploaded on 09/05/2024

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Name : Sumit Raghunath Rathod
UID : 2023800094
Branch : CSE DIV : B Batch : B
Experiment 1
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.
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Name : Sumit Raghunath Rathod

UID : 2023800094

Branch : CSE DIV : B Batch : B

Experiment 1

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.

DOS EDITOR :

  1. Edit.com: A simple text editor for DOS. It provides simple menu- driven interface where user can create and edit text file.
  2. QBasic: Its not only text editor but also an IDE for BASIC programming. It includes a simple text editor that can be used to edit and write BASIC programs. **DOS ASSEMBLER :
  3. MASM(Microsoft Macro Assembler) :** MASM is an assembler for the x86 family of microprocessors. It converts .asm files to .obj file which are then linked to create .exe file and run program. Conclusion : I understood x86 Mode and DOS Operating System and its basic commands. I learned how to install DOSBOX and run basic programs in DOS using MASM assembler.