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Patent Title: Installation and use of plural expanded memory managers

Assignee: IBM
Patent Number: US5623618
Issue Date: 04-22-1997
Application Number:
File Date:06-07-1995

Abstract: Simultaneous use of multiple expanded memory cards and their associated Expanded Memory Manager (EMM) device drivers in a computer system is provided. First, an expanded memory card is added and its EMM device driver will check to verify if another EMM driver is currently installed. If so, the new EMM device driver will take control of the existing EMM device driver in a master-slave relationship. The new EMM device driver (master) controls the existing EMM device driver (slave) by use of the slave's interrupt vector. That is, the master controls the slave by having an interrupt vector for the slave readdressed to be input to the master. Thereby, providing the master with the which expanded memory interrupts the slave was required to service. The master also takes control of all the slave's handles and pages by appearing as a requesting program application to the slave. Another feature of the present invention will allow multiple EMM device drivers to be installed in an efficient manner, by eliminating code that is redundant between existing and newly added EMM drivers.


Link to USPTO

IBM Pledge dated 1/11/2005