The TI PCI2040 is a PCI-DSP bridge that provides a glueless connection between the 8-bit host port interface (HPI) port on the TMS320C54X or the 16-bit HPI port on TMS320C6X to the high performance PCI bus. It provides a PCI bus target interface compliant with the PCI Local Bus Specification. The PCI2040 provides several external interfaces: the PCI bus interface with compact PCI support, the HPI port interface with support for up to four DSPs, a serial ROM interface, a general-purpose input/output interface (GPIOs), and a 16-bit general-purpose bus to provide a glueless interface to TI JTAG test bus controller (TBC). The PCI2040 universal target-only PCI interface is compatible with 3.3-V to 5-V signaling environments. The PCI2040 interfaces with DSPs via a data bus (HPI port). The PCI2040 also provides a serial ROM interface for preloading several registers including the subsystem ID and subsystem vendor ID. The PCI2040, compliant with the latest PCI Bus Power Management Interface Specification, provides serveral low-power features that reduce power consumption. Furthermore, an advanced CMOS process achieves low system power consumption. Unused PCI2040 inputs mus be pulled to a valid logic level using a pullup resistor.