Dual operating system computer
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United States of America Patent
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May 24, 1988
Grant Date -
N/A
app pub date -
Oct 9, 1985
filing date -
Oct 9, 1985
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
The UNIX.RTM. and MS-DOS.RTM. operating systems are supported in a multi-tasking computer. At the heart of the computer is a microprocessor having protected and non-protected modes. The computer includes special-purpose hardware which prevents the MS-DOS system and its applications, which execute in the non-protected mode, from interfering with the UNIX system and its applications, which execute in the protected mode. In particular, this hardware monitors addresses generated by the computer and, by selectively inhibiting the associated control pulses, prevents the MS-DOS system from, for example, writing in UNIX-system-allocated memory, or accessing I/O devices that the UNIX system is currently using. In addition, a context switching feature is provided whereby the user can select, via a keyboard operation, to have displayed on the computer video monitor at any given time the image generated from the current UNIX system screen data or the image generated from the current MS-DOS system screen data.
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