US 4,777,589 A · Direct input/output in a virtual memory system

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.

Claims7

Dependent claims

A computing system comprising:

a plurality of input/output devices, each input/output device including a plurality of registers for controlling the input/output device;
local memory means for storing data, the local memory means including a first plurality of physical storage locations;
system processing means for executing a plurality of processes the system processing means including:
virtual address mapping means for assigning a global virtual address to each physical storage location in the local memory means and for assigning a global virtual address to each register in each input/output device, wherein the virtual address for each physical storage location in the local memory and the virtual address for each register in each input/output device does not differ depending upon which process from the plurality of processes is executing.

1 more element

Dependencies are inferred from the claim text.

Direct input/output in a virtual memory system

Life of this patent

Direct input/output in a virtual memory system

Life of this patent

Abstract

Claims7