INFORMATION PROCESSOR CONTAINING TASK SWITCHING CONTROL MECHANISM

摘要

PURPOSE:To accurately perform the task switch processing by checking the presence or absence of an interruption as well as the privilege state immediately before the tasks are switched. CONSTITUTION:An instruction is held by a memory 19 and supplied to a decoder 12 through a bus 14 and then a bus interface 13. The interface 13 sends instructions to a flag 10 showing a protection level as well as to a flag 11 showing the presence or absence of an interruption. These two flags are reset when they shifted to each state. The output of the flag 10 and the inverse output of the flag 11 are supplied to an AND gate 15. An AND gate 16 supplies the output of the gate 15 and the signal that interpreted an instruction deciding the switch of tasks by the decoder 12 and outputs a signal 17 which shifts the operation to the task switch processing.