| 摘要 |
PURPOSE:To evaluate a real time control program without interrupting execution of the program by incorporating a DMA controller and an executing unit containing a HOLD function. CONSTITUTION:When a DMA request terminal 4 is activated, a DMA controller 3 is started to deliver an internal bus to an executing unit 2 and outputs a HOLD request signal 5. The unit 2 outputs a HOLD acknowledge signal 6 at the break of an executing cycle and at the same time opens the internal bus to be set in a HOLD state. The controller 3 outputs a prescribed address to the internal bus simultaneously with confirmation of the signal 6 and reads data out of the internal bus to write them into an input/output port 7. Then the controller 3 enables a port read enable terminal 9 and at the same time release the signal 5. The unit 2 releases the HOLD state and continues execution of a program to be evaluated. |
