IN-CIRCUIT EMULATOR DEVICE

摘要

PURPOSE:To simply and effectively execute circuit emulation by providing this in-circuit emulator device with an in-circuit emulation means and an adaptor circuit for connecting/disconnecting an MPU address bus to/from an MPU/ DRAM address bus based upon a memory control signal. CONSTITUTION:Control signals such as a row address selection signal nRAS and a column address selection signal nCAS are outputted from a DRAM controller 4 to a DRAM block 6. Only when these signals are outputted at the reading or writing timing from/in the block 6, they are detected by a three-state buffer control circuit 11. Thereby a three-state buffer 9 is set up to high impedance by an enable signal EN and the generation of address interference between the MPU address bus 2 and the MPU/DRAM row/column address bus 7 can be prevented. Thus in-circuit simulation can be simply and accurately executed while preventing the generation of address interference.