This article was previously published under Q82731
WIN.COM is the program that starts the Microsoft Windows operating systemversion 3.1 startup process. WIN.COM also performs the functions below.
WIN.COM makes the following preliminary checks to ensure that Windows can be started:
Is the minimum amount memory required to start Windows available?.
Verifies that Windows is not already running.
Verifies that the necessary binaries Windows needs to execute are available.
WIN.COM decides whether to start Windows in standard mode or 386 enhanced mode depending on available XMS memory and the processor type. WIN.COM starts 386 enhanced mode if it finds at least 1024KB available XMS memory and is on a 80386 computer; otherwise, WIN.COM starts in standard mode. If the machine has less than about 256K XMS memory, WIN.COM refuses to start Windows at all.
If WIN.COM is either forced or decides to start in standard mode, it first executes the task switcher (WSWAP.EXE). This is the terminate-and-stay-resident (TSR) program that allows Windows to switch among MS-DOS applications and Windows while running in standard mode.
The following is a list of WIN.COM switches and their functions:
WIN [/3] [/S] [/B] [/D:[F][S][V][X]] /? Prints this instruction banner. /3 Starts Windows in 386 enhanced mode. /S Starts Windows in standard mode. /2 Synonym for the /S switch. /B Creates a file, BOOTLOG.TXT, that records system messages. generated during system startup (boot). /D Used for troubleshooting when Windows does not start correctly. :F Turns off 32-bit disk access. Equivalent to SYSTEM.INI [386enh] setting: 32BitDiskAccess=FALSE. :S Specifies that Windows should not use ROM address space between F000:0000 and 1 MB for a break point. Equivalent to SYSTEM.INI [386enh] setting: SystemROMBreakPoint=FALSE. :V Specifies that the ROM routine handles interrupts from the hard drive controller. Equivalent to SYSTEM.INI [386enh] setting: VirtualHDIRQ=FALSE. :X Excludes all of the adapter area from the range of memory that Windows scans to find unused space. Equivalent to SYSTEM.INI [386enh] setting: EMMExclude=A000-FFFF.