Abstract: A personal computer when attempting to boot from a diskette (5) searches the boot record of the diskette for com. When found, com and the eight characters preceding com in the boot record are compared with the first two entries of the directory of the diskette. If no match is found, the personal computer responds on the basis of the diskette being a data diskette. Otherwise, the personal computer executes the boot record of the diskette. This minimizes error messages and operator involvement.

Abstract: A computer system with an internal operating system located in ROM is initialized in that operating system but can also automatically be directly initialized in an operating system of choice such as one located on an external memory, that is, a diskette or fixed disk. The computer system may also automatically be directly initialized in an application running under the internal operating system and, if desired, initialization may automatically directly include a customized version of the internal operating system. These customizing features are obtained through a customization word located in permanent read/write memory.

Abstract: A computer system with read-only memory and permanent read/write memory provides the user with the capability of loading an alternate operating system at the conclusion of a session without turning the computer off and then on. A customization word with a system request (SR) bit is located in read/write memory and is set by routines located in ROM upon user request. A reinitialization is then forced which resets the SR bit and brings up the machine in the alternate operating system located in external memory on a diskette or fixed disk. A flexible initialization system is also disclosed providing customized initialization in a variety of operating systems and applications. The preferred customized initialization is maintained for future system start-ups due to the resetting of the SR bit.