GENERAL DESCRIPTION
The Am79C90 CMOS Local Area Network Controller for Ethernet (C-LANCE) is a 48-pin VLSI device designed to greatly simplify interfacing a microcomputer or minicomputer to an IEEE 802.3/Ethernet Local Area Network. The C-LANCE, in conjunction with the Am7992B Serial Interface Adapter (SIA), Am7996 or Am79C98 and Am79C100 Transceiver, and closely coupled local memory and microprocessor, is intended to provide the user with a complete interface module for an Ethernet network. The Am79C90 is designed using a scalable CMOS technology and is compatible with a variety of microprocessors. On-board DMA, advanced buffer management, and extensive error reporting and diagnostics facilitate design and improve system performance.

DISTINCTIVE CHARACTERISTICS
■ Compatible with Ethernet and IEEE 802.3 10BASE-5 Type A, and 10BASE-2 Type B, “Cheapernet,” 10BASE-T
■ Easily interfaced with 80x86, 680x0, Am29000, Z8000™ microprocessors
■ On-board DMA and buffer management, 64-byte Receive, 48-byte Transmit FIFOs
■ 24-bit-wide linear addressing (Bus Master Mode)
■ Network and packet error reporting
■ Back-to-back packet reception with as little as 0.5 µs interframe spacing
■ Diagnostic Routines
   — Internal/external loopback
   — CRC logic check
   — Time domain reflectometer
■ Low power consumption for power-sensitive applications
■ Completely software- and hardware-compatible with AMD’s LANCE device (Am7990) (see Appendix A)