VxD is the device driver model used in Microsoft Windows/386 2.x, the 386 enhanced mode of Windows 3.x, Windows 9x, and to some extent also by the Novell DOS 7, OpenDOS 7.01, and DR-DOS 7.02 multitasker (TASKMGR). VxDs have access to the memory of the kernel and all running processes, as well as raw access to the hardware. Starting with Windows 98, Windows Driver Model was the recommended driver model to write drivers for, with the VxD driver model still being supported for backward compatibility, until Windows Me.
NTLDR is the boot loader for all releases of Windows NT operating system from 1993 with the release of Windows NT 3.1 up until Windows XP and Windows Server 2003. From Windows Vista onwards it was replaced by the BOOTMGR bootloader. NTLDR is typically run from the primary storage device, but it can also run from portable storage devices such as a CD-ROM, USB flash drive, or floppy disk. NTLDR can also load a non NT-based operating system given the appropriate boot sector in a file.
Windows 9x is a generic term referring to a line of discontinued Microsoft Windows operating systems from 1995 to 2000, which were based on the Windows 95 kernel and its underlying foundation of MS-DOS, both of which were updated in subsequent versions. The first version in the 9x series was Windows 95, which was succeeded by Windows 98 and then Windows Me, which was the third and last version of Windows on the 9x line, until the series was superseded by Windows XP.
For Microsoft Windows, OS/2, and DOS, .exe is the filename extension that denotes a file as being executable – a computer program – containing an entry point.
CONFIG.SYS is the primary configuration file for the DOS and OS/2 operating systems. It is a special ASCII text file that contains user-accessible setup or configuration directives evaluated by the operating system's DOS BIOS during boot. CONFIG.SYS was introduced with DOS 2.0.
The Installable File System (IFS) is a filesystem API in MS-DOS/PC DOS 4.x, IBM OS/2 and Microsoft Windows that enables the operating system to recognize and load drivers for file systems.
Quarterdeck Expanded Memory Manager (QEMM) is a memory manager produced by Quarterdeck Office Systems in the late 1980s through the late 1990s. It was the most popular third-party memory manager for the MS-DOS and other DOS operating systems.
AUTOEXEC.BAT is a system file that was originally on DOS-type operating systems. It is a plain-text batch file in the root directory of the boot device. The name of the file is an abbreviation of "automatic execution", which describes its function in automatically executing commands on system startup; the filename was coined in response to the 8.3 filename limitations of the FAT file system family.
The Windows Registry is a hierarchical database that stores low-level settings for the Microsoft Windows operating system and for applications that opt to use the registry. The kernel, device drivers, services, Security Accounts Manager, and user interfaces can all use the registry. The registry also allows access to counters for profiling system performance.
IO.SYS is an essential part of MS-DOS and Windows 9x. It contains the default MS-DOS device drivers and the DOS initialization program.
ntoskrnl.exe, also known as the kernel image, contains the kernel and executive layers of the Microsoft Windows NT kernel, and is responsible for hardware abstraction, process handling, and memory management. In addition to the kernel and executive layers, it contains the cache manager, security reference monitor, memory manager, scheduler (Dispatcher), and blue screen of death.
The Session Manager Subsystem, or smss.exe, is a component of the Microsoft Windows NT family of operating systems, starting in Windows NT 3.1. It is executed during the startup process of those operating systems.
HIMEM.SYS is a DOS device driver which allows DOS programs to store data in extended memory according to the Extended Memory Specification (XMS). The memory beyond the first 1 MB of address space is required by Windows 9x/Me in order to load; therefore, these versions of Microsoft Windows require HIMEM.SYS to be loaded to be able to run.
.sys is a filename extension used in MS-DOS applications and Microsoft Windows operating systems. They are system files that contain device drivers or hardware configurations for the system.
SYSTEM.INI is an initialization used in early versions of Microsoft Windows to load device drivers and the default Windows shell, among other system settings. Many of these settings were honored in Windows 9x, although the INI files had begun to be phased out in favor of the Windows Registry. Windows NT 4.0, 2000, XP and Server 2003 still acknowledge some SYSTEM.INI entries in order to provide backwards compatibility with older 16-bit applications. Windows Vista and beyond also have SYSTEM.INI as well. However, when a fresh install of XP/Server 2003 is performed, the SYSTEM.INI file created contains by default only these lines:
The booting process of Microsoft Windows varies between different releases.
SmartDrive is a disk caching program shipped with MS-DOS versions 4.01 through 6.22 and Windows 3.0 through Windows 3.11. It improves data transfer rates by storing frequently accessed data in random-access memory (RAM).
MSCDEX or Microsoft CD-ROM Extensions is a software program produced by Microsoft and included with MS-DOS 6.x and certain versions of Windows to provide CD-ROM support. Earlier versions of MSCDEX since 1986 were installable add-ons for MS-DOS 3.1 and higher.
DOS is a family of disk-based operating systems for IBM PC compatible computers. The DOS family primarily consists of IBM PC DOS and a rebranded version, Microsoft's MS-DOS, both of which were introduced in 1981. Later compatible systems from other manufacturers include DR-DOS (1988), ROM-DOS (1989), PTS-DOS (1993), and FreeDOS (1998). MS-DOS dominated the IBM PC compatible market between 1981 and 1995.
MS-DOS 7 is a real mode operating system for IBM PC compatibles. Unlike earlier versions of MS-DOS, it was not released separately by Microsoft, but included in the Windows 9x family of operating systems. Windows 95 RTM reports it as MS-DOS 7.0, and Windows 95 OSR 2.x and Windows 98 report as 7.1. The real-mode MS-DOS 7.x is contained in the IO.SYS file.
