File and record managementThe DOS kernel implements MS-DOS as it is seen by application programs. The kernel is a proprietary program supplied by Microsoft Corporation and provides a collection of hardware-independent services called system functions. These functions include the following:
File and record management
Memory management
Character-device input/output
Spawning of other programs
Access to the real-time clock
Programs can access system functions by loading registers with function-specific parameters and then transferring to the operating system by means of a software interrupt.
The DOS kernel is read into memory during system initialization from the MSDOS.SYS file on the boot disk. (The file is called IBMDOS.COM in PC-DOS.) This file is marked with the attributes hidden and system.