| 摘要 |
PURPOSE:To diagnose a memory IC without using a microprocessor, and also, in a short period by storing in advance diagnostic pattern data in a ROM. CONSTITUTION:When a diagnostic mode is set, a controlling circuit 4 gives an instruction to an input data switching circuit 1 so that an input data to a storing circuit 2 becomes a diagnostic pattern data TD. Also, a control signal RC is sent to a ROM circuit 3, and when information of the control signal RC is an instruction of generation of a data, a diagnostic pattern data TD is generated, and through an input data switching circuit 1, the diagnostic pattern data TD is written in a memory IC of the storing circuit 2. After the diagnostic pattern data TD has been written, a write/read-out signal W/R is changed to a read-out instruction, the diagnostic pattern data which has been written from the storing circuit 2 is read out, and at the same time, the control signal RC from the controlling circuit 4 is changed to a data comparing instruction, the data TD before write and the read-out data RD are compared by the ROM circuit 3, and a coincidence/dissidence signal TR is outputted.
|
