| 摘要 |
PURPOSE:To quickly test an address bus by setting a register on an address bus of a conventional circuit and executing an address bus test program with addition of a small number of circuits including a gate circuit, etc. CONSTITUTION:A register 4 has its output connected an input/output controller 3 and its input connected to an address bus line 10 respectively. An output line 22 is added to the controller 3 to transmit a turn-on signal when the 1st specific data is sent to the controller 3 and to turn off said turn-on signal when the 2nd specific data is sent to the controller 3. Then the gate circuits 23 and 25 latch the contents of the line 10 supplied to the register 4 by the memory read signal that is transmitted only when data are read out of a memory at output of a turn-on signal through the line 22. A CPU 1 latches the signals having all bits '0' and '1' sent to the line 10 via the register 4 and reads these signals out of the register 4 via the controller 3 to check the coincidence between this latched signal with the signal sent previously to the line 10. |
