The ES1980 MaestroTM-3 PCI audio-modem accelerator combines advanced audio and modem functionality in a highly integrated PCI solution for notebook systems. It uses the highbandwidth PCI bus to deliver advanced PC audio features, such as HRTF 3D positional audio, DirectSound acceleration and DVD AC-3 5.1 to 2 speaker virtualization. The ES1980 implements multistream DirectSoundTM and DirectSound3DTM acceleration with digital mixing, sample rate conversion, and HRTF 3D filtering. The ES1980 maintains full DOS legacy audio compatibility over the standard PCI 2.1 and PCI 2.2 buses. The ES1980 is designed for high-performance consumer multimedia notebook PC applications. The ES1980 includes a programmable audio signal processor and provides simultaneous support for multiple audio streams. With its built-in DSP core, the ES1980 uses its dedicated direct memory access (DMA) engine to handle complex signal processing tasks with a bus-mastering PCI interface. The support functions ensure efficient transfer of audio data streams to and from system memory buffers, providing a system solution with maximum performance and minimal host CPU loading. The architecture enables implementation of communications over the Internet from multiple sources. The ES1980 incorporates an HSP modem interface via its ACLink connecting with the ES2828 MC`97 codec. The MC`97 is used as the analog front end for the modem and DAA control. The V.90 modem runs on the host while the ES1980 serves as the bidirectional buffer for data transmission and reception. The modem functions include the standard AT command set, V.42bis and Group 3 fax.