DOS MCQ Questions

FCBS (File Control Blocks) in CONFIG.SYS specifies the number of file control blocks that can be opened simultaneously, supporting legacy file-sharing mechanisms. This setting is rarely needed with modern DOS versions using file handles instead. FCBS maintains compatibility with older programs designed for file control block-based file access methods.

FALSE - DOS is a single-tasking operating system that runs only one program at a time, unable to execute multiple applications concurrently. Users must exit one program before launching another, lacking the multitasking capabilities of modern operating systems. This limitation reflected hardware constraints of early PCs, with multitasking only available in later systems like Windows.

MOVE transfers files from one location to another, removing them from the source while placing them at the destination. Unlike COPY which duplicates files, MOVE relocates them entirely. RENAME only changes names within the same directory, and DISKCOPY duplicates entire disks rather than individual files, making MOVE the correct choice for file transfer.

/Y suppresses confirmation prompting when the MOVE command would overwrite existing files at the destination, enabling automated file movement in batch scripts. Without /Y, MOVE asks for user confirmation before replacing files, interrupting unattended operations. This switch is essential for automated file management and system administration tasks requiring reliable, non-interactive execution.

RESTORE recovers files from backup disks created by the BACKUP command, extracting archived files back to their original locations. This external command is essential for disaster recovery, restoring files after disk failures or accidental deletions. RESTORE requires the backup media created by BACKUP and can selectively recover individual files or entire directory trees.

Ctrl+C breaks (interrupts) execution of the currently running command or program in DOS, allowing users to stop processes that are taking too long or were started by mistake. This keyboard interrupt sends a termination signal to the active process. Ctrl+C is essential for regaining control when programs hang or when you need to cancel operations before completion.

APPEND is an external command (requiring APPEND.EXE) that establishes a search path for data files similar to how PATH works for executables. Internal commands like DIR, BREAK, and PATH are built into COMMAND.COM and execute without loading external programs. The distinction matters because external commands require the program file to be accessible on disk.

DIR S* lists all files and directories beginning with the letter 's', using the asterisk wildcard to match any characters after 's'. The wildcard pattern enables filtering directory listings to show only items matching specific criteria. This command helps locate files quickly when you know the starting characters of the filename but not the complete name.

All advantages apply to batch files: they save time by automating repetitive tasks, require fewer keystrokes by executing multiple commands from one file, and reduce errors by eliminating manual command entry. Batch files (.BAT) contain sequences of DOS commands that execute automatically, enabling task automation and consistent execution. They're essential for system administration, software installation, and routine maintenance operations.

CHKDSK (Check Disk) does not display the number of executable files; it shows storage capacity, free space, number of files (including hidden), and disk structure information. CHKDSK focuses on disk integrity, file system health, and space usage rather than categorizing files by type. It reports total disk space, bytes used, bytes available, and file/directory counts for file system analysis.

TRUE - The LABEL command assigns or changes the volume label (name) of a disk in DOS, providing a descriptive identifier for the disk. Volume labels appear when listing directory contents and help identify disks, especially when managing multiple drives. The command syntax is 'LABEL [drive:] [label]' to set or modify the disk's volume name.

VOL displays the volume label (disk name) and serial number of the specified drive or current drive if none is specified. Volume labels provide descriptive names for disks, helping identify different media and organizational purposes. The VOL command is useful for verifying disk identity before performing operations and managing multiple storage devices.

The EXPAND command decompresses files that have been compressed using Microsoft's compression format. These compressed files typically have an underscore as the last character in their extension (like FILE.EX_). The command is primarily used to extract files from installation disks or system files that were compressed to save space during distribution.

GOTO is not an external command; it's a batch file statement that transfers control to a labeled line within the batch file. External commands like COMMAND.COM (though special), DBLSPACE (disk compression), and DELTREE (recursive delete) are separate executable files. GOTO exists only within batch file context and cannot be executed as a standalone command.

MSCDEX.EXE (Microsoft CD-ROM Extensions) is the CD-ROM driver for DOS. The LH (LoadHigh) command loads it into upper memory to save conventional memory. The /D:123 parameter specifies the device name that matches the CD-ROM device driver loaded in CONFIG.SYS. This line is essential for DOS systems to recognize and access CD-ROM drives.

All options are valid: DOSKEY recalls previous MS-DOS commands for reuse, enables editing of command lines before execution, and creates macros for frequently-used command sequences. This TSR utility enhances command-line productivity by maintaining command history accessible with arrow keys and supporting command-line editing. DOSKEY macros automate repetitive tasks by assigning short names to complex command sequences.

The APPEND command creates a search path for data files, similar to how PATH works for executable files. When a program looks for a data file, DOS searches the directories specified by APPEND. This allows programs to access files in other directories without specifying full paths. APPEND is useful when applications expect files in the current directory but they're stored elsewhere.

REN C:\FOO.TXT D:\BAR.TXT is syntactically incorrect because the REN/RENAME command cannot move files between drives or directories; it only renames files within the same directory. The rename command takes the source filename and new name without path information for the destination. To move files between drives or directories, use the MOVE or COPY commands instead.

DIR (Directory) lists all files and subdirectories in the current directory, displaying names, sizes, dates, and times. The command can include parameters like '/P' for paused output or '/W' for wide format. DIR is one of the most frequently used DOS commands, providing essential file system navigation and information discovery capabilities.

The TREE command with the /F switch displays a graphical tree structure of directories and includes files in the listing. The TREE command without /F shows only directories. The /F parameter adds file names to the tree view, making it useful for visualizing the complete folder structure with all contained files.

SYS is not an executable extension in DOS; it's used for system files like IO.SYS and MSDOS.SYS rather than programs users can run directly. The executable extensions are COM (compact binary programs), EXE (larger executable programs), and BAT (batch files containing command sequences). Understanding executable extensions is crucial for DOS command execution order and program loading.

The correct DOS boot sequence is: MSDOS.SYS (loads DOS kernel), CONFIG.SYS (configures system), COMMAND.COM (loads command interpreter), then AUTOEXEC.BAT (runs startup commands). This ordered sequence initializes the operating system, configures devices and memory, establishes the user interface, and executes custom startup procedures. Understanding boot sequence helps diagnose startup problems and optimize system configuration.