The 'BCT2420 was designed using Texas Instruments BiCMOS process, which features bipolar drive characteristics and greatly reduces the standby power of the device when disabled. This feature is especially valuable when the device is not performing a NuBusTM transaction. The AEN, DEN and ADEN inputs control the transceiver functions. Three 16-bit I/O ports, A15A0, D15D0, and AD15AD0, provide for address and data transfer. When the NuBusTM performs a write cycle to the local board, address information is saved on the rising edge of ACLK. During the last portion of the NuBusTM write cycle, data information is saved on the rising edge of DCLK. When the local board is performing a write to the NuBusTM, address and data is multiplexed onto the NuBusTM via the A/D line. Address and data can be latched by using the ALE and DLE input lines respectively. The IDEQ output is used to signal that the local board is being requested by the NuBusTM. This output is typically fed to the NuBusTM controller. IDEQ goes active (low) when AD15AD12 are low and AD11AD8 match ID3ID0. IDEQ stays valid until the next address clock (ACLK) occurs. Internal 10-k pullup resistors are included on the ID3ID0 inputs.