Patent ID: 8056088

Claim:
A plurality of scan chains configured to perform method for context switching operations, the scan chains comprising: a first scan chain, wherein the first scan chain includes: a first scanable state element coupled to context switchable logic, and configured to store state information and having a scan input coupled to an output of a memory controller; a second scanable state element coupled to context switchable logic, and configured to store state information and having a scan output coupled to an input of the memory controller; a second scan chain, wherein the second scan chain includes: a third scanable state element coupled to context unswitchable logic and configured to store state information; a fourth scanable state element coupled to context unswitchable logic and configured to store state information; wherein the first scanable state element and the second scanable state element are coupled to a first clock and the third scanable state element and the fourth scanable state element are coupled to a second clock; wherein state information stored in the second scanable state element is transmitted to the memory controller every clock cycle during a context save operation, and state information is transmitted from the memory controller to the first scanable state element every clock cycle during a context restore operation; wherein a scan enable signal is coupled to the first scanable state element, the second scanable state element, the third scanable state element and the fourth scanable state element; and wherein the first clock and the scan enable signal are active and the second clock is inactive during context save and context restore operations.