PRELIMINARY
Am79C90
CMOS Local Area Network Controller for Ethernet
(C-LANCE)
DISTINCTIVE CHARACTERISTICS
s Compatible with Ethernet and IEEE 802.3
10BASE-5 Type A, and 10BASE-2 Type B,
“Cheapernet,” 10BASE-T
s Easily interfaced with 80x86, 680x0, Am29000®,
Z8000™ microprocessors
s On-board DMA and buffer management, 64-byte
Receive, 48-byte Transmit FIFOs
s 24-bit-wide linear addressing (Bus Master Mode)
s Network and packet error reporting
s Back-to-back packet reception with as little as
0.5 µs interframe spacing
s Diagnostic Routines
— Internal/external loopback
— CRC logic check
— Time domain reflectometer
s Low power consumption for power-sensitive
applications
s Completely software- and hardware-compatible with
AMD’s LANCE device (Am7990) (see Appendix A)
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.
BLOCK DIAGRAM
Local CPU Interface
A23:16
INTR
HOLD
HLDA
ALE/AS
CS
ADR
DAS
DALO
DALI
READ
BM0/BYTE
BM1/BUSAKO
READY
RESET
Parallel
Bus
Interface
DMA/Data
Path Control
C-LANCE/
CPU
Control
Bus
Interface
Station
Address
Detection
Retry
Logic
Microprogram
Store
Serial I/O
Interface
RX
RCLK
TX
TCLK
CLSN
TENA
RENA
Am7992B SIA Interface
DAL15:0
17881C-1
Publication# 17881 Rev: C Amendment/0
Issue Date: January 1998
This document contains information on a product under development at Advanced Micro Devices. The
information is intended to help you evaluate this product. AMD reserves the right to change or discontinue
work on this proposed product without notice.
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