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:
Oct. 11, 1988
Filed:
Jun. 28, 1985
Steven C Boettner, San Jose, CA (US);
William R Bryg, Saratoga, CA (US);
David V James, Palo Alto, CA (US);
Tso-Kai Liu, Saratoga, CA (US);
Michael J Mahon, San Jose, CA (US);
Terrence C Miller, Menlo Park, CA (US);
William S Worley, Jr, Saratoga, CA (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A virtual memory system is used to control access to I/O device address space in accordance with a preferred embodiment of the present invention. In a virtual memory system, access to pages within a processor's address space are assigned to each application program. Each I/O device is assigned two pages of address space. One page is considered to be privileged, and the other unprivileged. Each I/O device register is associated with an address in each of the two pages of its I/O device address space. Address space is global. What is meant by global is that physical memory locations map to the same virtual memory space regardless of what process is running on the processor. Access codes accompanied by a write disable bit are used to control process access to various addresses.