The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 31, 1994
Filed:
Jul. 26, 1993
Richard G Pechter, Escondido, CA (US);
NCR Corporation, Dayton, OH (US);
Abstract
An apparatus for extending the memory of an electronic data processing system and a method for providing access to the extended memory for reading data, writing data, and refreshing data. The method provides a partitioning of the original virtual address space into a reduced virtual address space and an extended real memory address space. An extended address register is loaded initially with an extended memory control word by the operating system, but this word may not be changed again until the current process is over. If this control word is changed, it is changed by the operating system such that the use of the extended memory is transparent to the application processes using the system. The method further provides for refreshing of the memory circuitry of the extended memory. The apparatus supports the extended real memory address space by decoding the read and write accesses to the extended real address space, and by providing electrical connections for the refreshing of the extended memory circuitry. Thus, with this apparatus and method, the real memory of an electronic data processing system may be multiplied by a factor of two, four, or some higher multiple of two.