
MSDOS.SYS

MSDOS.SYS is a system file in MS-DOS and Windows 9x operating systems.
In versions of MS-DOS from 1.1x through 6.22, the file comprises the MS-DOS kernel and is responsible for file access and program management. codice_1 is loaded by the DOS BIOS codice_2 as part of the boot procedure. In some OEM versions of MS-DOS, the file is named codice_3.
In Windows 95 (MS-DOS 7.0) through Windows ME (MS-DOS 8.0), the DOS kernel has been combined with the DOS BIOS into a single file, codice_2 (aka codice_5), while codice_1 became a plain text file containing boot configuration directives instead. If a codice_7 file exists, the system will retrieve these configuration directives from codice_7 rather than from codice_1.
When Windows 9x is installed over a preexisting DOS install, the Windows file may be temporarily named codice_10 for as long as Windows' dual-boot feature has booted the previous OS. Likewise, the codice_1 of the older system is named codice_12 for as long as Windows 9x is active.
Some DOS utilities expect the codice_1 file to have a minimal file size of at least 1 KB. This is the reason why a large dummy comment is typically found in the codice_1 configuration file since Windows 95.
By default, the file is located in the root directory of the bootable drive/partition (normally codice_15 for hard disks) and has the hidden, read-only, and system file attributes set.
The MS-DOS derivative (DCP) by the former East-German VEB Robotron used a filename instead.
IBM PC DOS as well as DR DOS since 5.0 (with the exception of DR-DOS 7.06) used the file codice_16 for the same purpose, whereas DR DOS 3.31 to 3.41 used codice_17 instead. FreeDOS uses the file codice_18 for the same purpose.
Windows NT-based operating systems (NT 3.1-4, 2000, XP, and 2003) use the NTLDR file and NT 6+ operating systems (Vista, 2008, 7, 8, 8.1, and 10) use bootmgr instead, as they have a different boot sequence.
External links.
MSDOS.SYS in Windows 9x (95/98/ME):