A memory device which utilizes a plurality of memory modules coupled in parallel to a master I/O module through a single directional asymmetrical signal swing (DASS) bus. This structure provides an I/O scheme having symmetrical swing around half the supply voltage, high through-put, high data bandwidth, short access time, low latency and high noise immunity. The memory device utilizes improved column access circuitry including an improved address sequencing circuit and a data amplifier within each memory module. The memory device includes a resynchronization circuit which allows the device to operate either synchronously and asynchronously using the same pins. Each memory module has independent address and command decoders to enable independent operation. Thus, each memory module is activated by commands on the DASS bus only when a memory access operation is performed within the particular memory module. The memory device includes redundant memory modules to replace defective memory modules. Replacement can be carried out through commands on the DASS bus. The memory device can be configured to simultaneously write a single input data stream to multiple memory modules or to perform high-speed interleaved read and write operations. In one embodiment, multiple memory devices are coupled to a common, high-speed I/O bus without requiring large bus drivers and complex bus receivers in the memory modules.