METHOD AND SYSTEM FOR PROVIDING PROTECTED MODE DEVICE DRIVERS

A computer method and system for providing protected mode device drivers that are compatible with real mode device drivers. A first aspect of the invention provides consistent assignment of drive unit numbers with which the same physical disks are accessed by the real mode and protected mode physical disk drivers. A second aspect of the invention provides consistent assignment of volume unit numbers with which the same logical volumes are accessed by real mode and protected mode logical volume drivers. A third aspect of the invention provides consistent assignment of adapter numbers with which the same adapters are controlled by real mode and protected mode adapter drivers and mapping real mode adapter driver requests to protected mode adapter driver requests of the protected mode adapter drivers that control the same adapters. A fourth aspect of the invention provides detection and protected mode accommodation of real mode functional drivers which are provided in addition to the real mode device drivers in the real mode operating system.