Differential current switch—High performance at low power

The recent IBM System/390™ announcement includes six high-performance air-cooled models that use a low-power variation of emitter-coupled logic (ECL). This new logic family, called differential current switch (DCS), uses differential signal pairs to represent logic signals, and combines two-level cascode logic with dotting to implement a complete set of logic circuits. These DCS circuits are described in detail, and the relative value of the DCS and ECL logic families is discussed extensively.