Disk Operating System (DOS) MCQ Questions & Answers | Computer Science

External commands:
External commands in DOS are programs or executable files stored on the disk that are not built into the command interpreter (like command.com). These commands require additional files (the executable files themselves) to execute.

When you enter an external command in DOS, such as copy, dir, or format, DOS searches for the corresponding executable file on the disk and loads it into memory for execution. These commands are separate programs stored as files on the disk, and thus they need these files (external executables) to be present and accessible in order to run.

Internal commands:
Internal commands are built into the command interpreter (command.com) itself. They do not require additional files because their functionality is already integrated into the command interpreter. Examples of internal commands include dir, cd, mkdir, and type. These commands are part of the command interpreter and are available as soon as DOS is booted, without needing any additional files.

Batch commands:
Batch commands refer to sequences of commands stored in a file with a .bat extension. They are essentially scripts that contain a series of DOS commands to be executed sequentially. While batch files themselves are files that need to be accessed, the commands within them (if they are internal commands) do not require additional files beyond the command interpreter.

Redirectors:
Redirectors in DOS are symbols (>, <, >>) used to redirect input and output between commands and files. They do not themselves require additional files for execution; rather, they facilitate the manipulation of input and output streams.

Therefore, the correct answer is Option B: External commands, which require additional files for their execution.

MS-DOS 6.22 was the last standalone version of MS-DOS released by Microsoft. It was released in 1994 and was an upgrade from MS-DOS 6.0 and 6.2. MS-DOS 6.22 included various enhancements and utilities over its predecessors, such as improved memory management, disk utilities (like chkdsk and defrag), and enhanced file management capabilities.

During the early 1990s, MS-DOS was a widely used operating system for IBM-compatible personal computers, providing a command-line interface and supporting a variety of applications and games. With the rise of graphical user interfaces (GUIs) like Windows, MS-DOS gradually became integrated into Windows operating systems as a command-line interface rather than being released separately.

Therefore, the correct answer is Option D: 6.22, as it was the last standalone release of MS-DOS.

Changing file extensions in MS-DOS can be done using the ren (rename) command. Here’s how each option works:
Option A: Ren *.doc *.txt would attempt to rename files with .doc extension to .txt, which is the reverse of what is required.
Option B: Ren *.txt *.doc correctly renames all files with .txt extension to .doc.
Option C: Ren file.doc file.txt attempts to rename a specific file from file.doc to file.txt, not suitable for renaming all files.
Option D: Ren a: *.doc *.txt tries to rename files with .doc extension on drive a: to .txt, but the syntax is incorrect for this operation.

Therefore, Option B is the correct command to change the extension of all filenames ending with .txt to .doc in MS-DOS.

To combine file1 and file2 into a new file named file3 in MS-DOS, you would use the copy command with the + symbol to concatenate files. Here’s how each option works:
Option A: Copy file3 file1+file2 attempts to copy file3 as a combined file of file1 and file2, which is incorrect.
Option B: Copy file1+file2 file3 correctly combines file1 and file2 into a new file named file3.
Option C: Copy file1+file2+file3 does not follow the correct syntax for combining files in MS-DOS.
Option D: Copy file2 file1+file3 attempts to copy file2 and rename it to file1+file3, which is not the operation to combine files.
Therefore, Option B is the correct command to combine file1 plus file2 into a new file named file3 in MS-DOS.

To copy all files with the extension .txt into one file named all.txt in MS-DOS, you would use the copy command with the source files wildcard and specify the destination file. Here’s how each option works:
Option A: Copy a: *.txt attempts to copy all .txt files from drive a: but does not specify a destination file.
Option B: Copy *.txt a: attempts to copy all .txt files to drive a: without specifying a destination file name.
Option C: Copy *.txt c: attempts to copy all .txt files to drive c: without specifying a destination file name.
Option D: Copy *.txt all.txt correctly copies all .txt files in the current directory to a single file named all.txt.

Therefore, Option D is the correct command to copy all files with the extension .txt into one file named all.txt in MS-DOS.

To move a file from one directory to another in MS-DOS, you use the move command. Here’s how each option works:
Option A: Rename is used to rename a file or directory but does not move it to a different directory.
Option B: Copy is used to make a copy of a file or directory, but it does not remove the original file from its current location.
Option C: Move is used to move a file or directory from one location to another within the same drive or to a different drive in MS-DOS.
Option D: Cp is not a valid command in MS-DOS for copying or moving files.

Therefore, Option C is the correct command to move a file from one directory to another while working with MS-DOS.

To rename a file named file1.doc to file2.doc from a different directory dir1 in MS-DOS, you use the ren (short for rename) command. Here’s the explanation for each option:
Option A: Ren2.doc \dir\file1.doc is incorrect syntax. The correct format for renaming involves specifying the full path of the original file followed by the new filename.
Option B: Ren file1.doc file2.doc renames file1.doc to file2.doc in the current directory, not in a different directory.
Option C: Ren .doc\dir\.doc is incorrect syntax. It does not specify the correct path or filenames for renaming.
Option D: Ren \dir1\file1.doc file2.doc is the correct command to rename file1.doc located in directory dir1 to file2.doc.

Therefore, Option D is the correct command to rename a file from a different directory in MS-DOS.

To copy all files from the currently logged drive and directory with the extension .txt to drive A in MS-DOS, you would use the copy command with the appropriate syntax. Here’s the explanation for each option:
Option A: Copy a. *.txt is incorrect syntax. It does not correctly specify the destination drive.
Option B: Copy *.txt a: copies all files with the extension .txt from the current directory to drive A.
Option C: Copy *.txt c: attempts to copy .txt files to drive C, not drive A.
Option D: Copy *.txt all.txt attempts to copy .txt files to a file named all.txt, not to a specific drive.

Therefore, Option B is the correct command to copy all files with the extension .txt from the current directory to drive A in MS-DOS.

To recover accidentally deleted files in DOS, the correct command is UNDELETE. Here's the explanation for each option:
Option A: UNDELETE is the command used to recover accidentally deleted files in DOS.
Option B: DELETE/CANCEL is not a valid DOS command for file recovery. It seems to combine the delete and cancel concepts, which is not how file recovery operates.
Option C: RESTORE is not the correct command for recovering deleted files in DOS. It doesn't perform file recovery operations.
Option D: RECOVER is not the correct command for file recovery in DOS. It typically refers to recovering data from damaged disks, not recovering deleted files.

Therefore, Option A (UNDELETE) is the correct command to recover accidentally deleted files in DOS.

To set a name to a disk in DOS, the correct command is VOL. Here's the explanation for each option:
Option A: VOLUME is not the correct command in DOS to set a name to a disk.
Option B: VOL is used to display the disk volume label in DOS, not to set or change it.
Option C: LABEL is the correct command in DOS used to set or change the disk volume label. This command allows you to assign a name to a disk.
Option D: DISKLABEL is not a valid command in DOS.

Therefore, while Option C (LABEL) accurately describes the command used to set a name to a disk in DOS, Option B (VOL) specifically displays the current disk volume label and does not set or change it.