GENERAL DESCRIPTION
The enhanced Integrated Multiport Repeater Plus (eIMR+) device is a VLSI integrated circuit that provides a system-level solution to designing managed multiport repeaters. The device integrates the repeater functions specified in Section 9 of the IEEE 802.3 standard and Twisted Pair Transceiver functions complying with the 10BASE-T standard.

DISTINCTIVE CHARACTERISTICS
■ Repeater functions compliant with IEEE 802.3 Repeater Unit specifications
■ Direct interface with the Am79C987 Hardware Implemented Management Information Base (HIMIB™) device for building a basic managed multiport repeater
■ Full software backwards compatibility with existing hub designs using Integrated Multiport Repeater Plus (IMR+™)/HIMIB devices
■ Network management and optional feature accessibility through a dedicated serial management port
■ Four integral 10BASE-T transceivers with on chip filtering eliminating the need for external filter modules on the 10BASE-T transmit-data (TXD) and receive-data (RXD) lines
■ One Reversible Attachment Unit Interface (RAUI™) port used either as a standard IEEE compliant AUI port for connection to a Medium Attachment Unit (MAU) or a reversed port for direct connection to a Media Access Controller (MAC)
■ Low cost suitable for managed multiport repeater designs
■ Number of repeater ports easily expandable with support for up to seven eIMR+ devices without the need for an external arbiter
■ All ports capable of being individually isolated (partitioned) in response to excessive collision conditions or fault conditions
■ Flexible LED support for individual port status and network utilization LEDs
■ Programmable extended distance mode on RXD lines allowing connection to cables longer than 100 meters
■ Link Test function and Link Test pulse transmission capable of being disabled through the management port allowing devices that do not implement the Link Test function to work with the eIMR+ device
■ Programmable automatic polarity detection and correction option permitting automatic recovery from wiring errors
■ Full amplitude and timing regeneration for retransmitted waveforms
■ CMOS device with a single +5-V supply