公开(公告)号：JPH11288372A

公开(公告)日：1999-10-19

申请号：JP37431698

申请日：1998-12-28

Applicant: ST MICROELECTRONICS INC

Inventor： DAVID WON

IPC: G06F9/30 ,  G06F9/312 ,  G06F9/318 ,  G06F9/34 ,  G06F9/38 ,  G06F9/46

Abstract: PROBLEM TO BE SOLVED: To provide an improved device which can preserve and recover states of various registers in a microprocessor by providing a means to recover 1st sate information from a 1st register set when a 2nd task is switched to a 1st task if the 1st state information is not corrected. SOLUTION: A means is provided to recover 1st state information from a 1st register set when a 2nd task is switched to a 1st task as long as the 1st state information is not corrected. This device includes two sets of registers, i.e., registers 0 and 1. When a CPU stores a floating-point state or environment in a memory as an image, this state or environment is stored in an additional internal register as a copy. Then necessary information is recovered from the additional register when the CPU must recover the state or environment. Thus, it's possible to evade a case where the image is loaded again from a main memory.