Reduced cmos-swing clamping circuit for bus lines

Abstract

A memory system having several memory devices coupled to a memory controller through an I/O bus, each memory device including multiple memory modules coupled to a chip I/O interface through an internal bus. The system includes a circuit for driving the I/O bus with a reduced CMOS-swing, a circuit for driving the internal bus with a full CMOS-swing in one bus direction and with a reduced CMOS-swing in the other bus direction, a column address generation circuit for allowing sequentially addressed data to be accessed with the decoder delay being eliminated, and a circuit for re-synchronizing data from a source clock to a destination clock with reduced access latency penalty. Simultaneously writing data into multiple circuit modules significantly increases the write bandwidth of the memory. Also included are a dynamic base-address mapping into an address space, a read or write operation across multiple memory modules, a novel I/O bus format, and a protocol and test mode for testing redundant memory sub-arrays.