| 摘要 |
PURPOSE:To decrease the number of desired circuits, by using a microinstruction line between control units for the scan control information and scan-out data in a scan active mode, and providing only a mode display line between the control units. CONSTITUTION:A microinstruction line 230 is provided bilaterally between a unit 200 which performs execution and control of a microprogram and a unit 220 which controls the scanning operation. The line 230 is then connected to units 210-21n which are under the control of the microprogram. Thus the line 230 is used for transmission of the microinstruction in a normal operation mode of a data processor and then for transmission of the scan control information and scan-out data in a scan active mode respectively. For the exclusive use of scan control, just two mode display lines 240 and 241 are led out of the scan control unit 220. Then the line 240 is connected to each unit; while the line 241 is connected only to the unit 200. Thus a large number of circuits can be eliminated for control of the scan information to simplify the circuit constitution. |
