PROGRAM EXECUTION METHOD FOR SPECIFIC CASE PROCESSING AND APPARATUS USING THE SAME

摘要

When a process branches to an interrupt processing routine, the value stored in a return address holding register ERP is transferred to a register R2 via the initial MOVS instruction. Upon the next SETPR instruction (an acceptable interrupt level setting instruction), an EA (interrupt allowance) flag is automatically set at 1, whereby multiple interrupts are allowed. For process returning, the value saved in the register R2 is transferred to the ERP register via a data transfer instruction MOVS, upon which the EA flag is automatically set at 0 to thereby inhibit receipt of interrupt requests. Upon execution of the last RETI instruction, receipt of interrupt requests is again allowed.