The 73K224L is a highly integrated single-chip modem IC which provides the functions needed to construct a V.22bis compatible modem, capable of 2400 bit/s full-duplex operation over dial-up lines. The 73K224L  offers excellent performance and a high level of functional integration in a single 28-pin DIP and 44-pin TQFP package. This device supports V.22bis, V.22, V.21, Bell 212A and Bell 103 modes of operation, allowing both synchronous and asynchronous communication. The 73K224L is designed to appear to the systems designer as  a microprocessor peripheral, and will easily interface with popular single-chip microprocessors (80C51 typical) for control of modem functions through its 8-bit multiplexed address/data bus or via an optional serial control bus. An ALE control line simplifies address  demultiplexing. Data communications normally occur through a separate serial port. The 73K224L is pin and software compatible with the 73K212L and 73K222L single-chip modem ICs, allowing system upgrades with a single component change.