The TNETA1575 is an asynchronous transfer mode (ATM) segmentation and reassembly (SAR) device with a peripheral component interconnect (PCI)-bus interface and a coprocessor interface (COPI). The TNETA1575 continues the line of Texas Instruments (TI)TM ATM SAR devices directed toward the classical LAN-to-ATM translation market segment. Features have been extended to include the COPI interface, which interfaces to an external scheduler with high-performance features to eliminate polling on the PCI bus. The TNETA1575 is designed for the emerging class of high-performance enterprise networking hubs that utilize ATM in the backplane, in addition to the traditional frame-/packet-based bus systems. Some of the features required for this application include: high level of virtual channel/virtual path support, support for isochronous services, early segmentation, and high-performance, 32-bit PCI-bus support. The feature set required by cell-operating enterprise hubs is different from the sets being offered by other SAR devices, which are directed primarily toward the adapter card market.