In accordance with the present invention, a resume processing driver for an advanced microprocessor, such as the Intel 80386 operating in enhanced mode, is provided which saves data indicative of the operating conditions of the advanced microprocessor into system memory and then calls a previously existing resume processing routine designed for a previously existing operating system, such as MS-DOS operating in real mode. The previously existing resume processing routine performs additional processing in order to save operating condition data associated with the previously existing operating system into system memory, and then performs a controlled power off sequence and removes the power supplied to all elements of the computer except the computer memory. Thereafter, the existing resume processing routine performs processing to restore the operating condition data associated with the previously existing operating system from system memory and then passes control to the resume processing driver of the present invention. The resume processing driver restores the data indicative of the operating conditions of the advanced microprocessor from system memory, and control then passes to the computer program which was executing before the resume processing driver was initiated. In addition, in another embodiment, the present invention is able to properly switch from the enhanced mode to the real mode and then back to the enhanced mode for use in applications other than resume functions.