David D Doria

49282379, May 22, 1990

Mar 27, 1987

7/030789

Richard Bealkowski - Delray Beach FL
Richard A. Dayan - Boca Raton FL
David J. Doria - Boca Raton FL
Scott G. Kinnear - Boca Raton FL
Jeffrey I. Krantz - Boca Raton FL
Robert B. Liverman - Raleigh NC
Guy G. Sotomayor - West Palm Beach FL
Donald D. Williams - Boca Raton FL
Gary A. Vaiskauckas - Boca Raton FL

International Business Machines Corp. - Armonk NY

G06F 900

364200

A computer system and method for operating a computer system capable of running in mutually incompatible real and protected addressing modes, in which programs written for one mode can be run in the other mode without modification. The operating system using BIOS assembles two different common data areas for the two modes, each inclusive of device block pointers, function transfer table pointers, data pointers, and function pointers. The common data area for the real mode is assembled first. To assemble the pointers for the protected mode common data area, the offset values from the real mode area are copied directly, and then selector values are inserted whose physical addresses correspond to the segments of the corresponding pointers in the real mode area. The selector values are derived from a segment descriptor table.

51931613, Mar 9, 1993

May 18, 1990

7/525792

Richard Bealkowski - Delray Beach FL
Richard A. Dayan - Boca Raton FL
David J. Doria - Boca Raton FL
Scott G. Kinnear - Boca Raton FL
Jeffrey I. Krantz - Boca Raton FL
Robert B. Liverman - Raleigh NC
Guy G. Sotomayor - West Palm Beach FL
Donald D. Williams - Boca Raton FL
Gary A. Vaiskauckas - Boca Raton FL

International Business Machines Corp. - Armonk NY

G06F 1200
G06F 9445

395400

A computer system and method for operating a computer system capable of running in mutually incompatible real and protected addressing modes, in which programs written for one mode can be run in the other mode without modification. The BIOS assembles two different common data areas for the two modes, each inclusive of device block pointers, function transfer table pointers, data pointers, and function pointers. The common data area for the real mode is assembled first. To assembly the pointers for the protected mode common data area, the offset values from the real mode area ae copied directly, and then selector values are inserted whose physical addresses correspond to the segments of the corresponding pointers in the real mode area. The selector values are derived from a segment descriptor table.