DM74LS257B

These DM74LS257B Schottky-clamped high-performance multiplexers feature TRI-STATE outputs that can interface directly with data lines of bus-organized systems.With all but one of the common outputs disabled(at a high impedance state),the low impedance of the single enabled output will drive the bus line to a high or low logic level.To minimize the possibil-ity that two outputs of DM74LS257B will at tempt to take a common bus to opposite logic levels ,the output enable circuitry is designed such that the output disable times are shorter than the out- put enable times.

This TRI-STATE output feature means that n-bit(paralleled) data selectors with up to 258 sources can be implemented for data buses. It also permits the use of standard TTL reg-isters for data retention throughout the system.