Computer with capability to automatically initialize in a first operating system of choice and reinitialize in a second operating system without computer shutdown
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.
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.
A hybrid system environment includes a proprietary operating system and processing unit and a non-proprietary operating system (UNIX based) and processing unit. The systems tightly couple to a system bus in common with a main memory and a number of multiline communications controllers and communicate through a common area of main memory. The UNIX terminal connections to such controllers are virtual connections applied by a virtual terminal driver through the system proprietary communications software components. These components include a server, a network terminal driver (NTD) and a number of multiplexer driver modules. A multiplexer physical terminal driver is included in the UNIX-based operating system and a switching mechanism is incorporated into the virtual terminal driver for enabling switching to such physical terminal driver when a user switches via a switch command to the UNIX-based operating system. The server module upon being invoked upon such switching operates to establish a direct communications path between an application running under the UNIX-based operating system and the controller communications line paths through the multiplexer driver module and logically disconnects the virtual communications line path from the NTD module to the multiplexer driver module thereby improving system efficiency and terminal connectivity.
A data processing system, such as a personal computer, contains bootable DOS programs that are stored in a ROM as an alternate file system in which the files are stored in packed format. When the system is powered on, the programs are rapidly booted up or loaded from ROM into RAM and executed to "instantly" (as it appears to the user) place the system in operation.
Disclosed is a technique for overcoming the 1-Mbyte mode memory limitation associated with "real-mode" operation of certain Intel Corp. microprocessor architectures. This limitation can be overcome by altering the contents of a register portion that is computationally meaningful only in "protected mode," but which persists and exerts effects in real mode. By indirectly manipulating the contents of this register portion in protected mode in a manner that avoids disruption to the register during the switch back to real mode, access can be obtained, in real mode, to up to 4 Gbytes of volatile memory.
