Publication#
18681
Issue Date:
October 1994
Rev.
B
Amendment
/1
This document contains information on a product under development at Advanced Micro Devices, Inc. The information is intended
to help you to evaluate this product. AMD reserves the right to change or discontinue work on this proposed product without notice.
Advanced
Micro
Devices
Am79C974
PCnet
TM
-SCSI Combination Ethernet and SCSI Controller
for PCI Systems
PRELIMINARY
DISTINCTIVE CHARACTERISTICS
PCI Features
I
Direct glueless interface to 33 MHz, 32-bit PCI
local bus
I
132 Mbyte/s burst DMA transfer rate
I
Compliant to PCI local bus Specification
Revision 2.0
Ethernet Features
I
Supports ISO 8802-3 (IEEE/ANSI 802.3) and
Ethernet Standards
I
High-performance Bus Master architecture with
integrated DMA Buffer Management Unit for
low CPU and bus utilization
I
Individual 136-byte transmit and 128-byte
receive FIFOs provide frame buffering for
increased system latency
I
Microwire
TM
EEPROM interface supports
jumperless design
I
Integrated Manchester Encoder/Decoder
I
Provides integrated Attachment Unit Interface
(AUI) and 10BASE-T transceiver with automatic
port selection
I
Automatic Twisted-Pair receive polarity detec-
tion and automatic correction of the receive
polarity
I
Dynamic transmit FCS generation programma-
ble on a frame-by-frame basis
I
Internal/external loopback capabilities
I
Supports the following types of network
interfaces:
— AUI to external 10BASE2, 10BASE5,
10BASE-T or 10BASE-F MAU
— Internal 10BASE-T transceiver with Smart
Squelch to Twisted-Pair medium
SCSI Features
I
Compliant to ANSI standards X3.131 – 1986
(SCSI-1) and X3.131 – 199X (SCSI-2)
I
Fast 8-bit SCSI-2 10 Mbyte/s synchronous or
7Mbyte/s asynchronous data transfer rate
I
SCSI specific Bus Mastering DMA engine
(32-bit address/data)
I
96-byte DMA FIFO for low bus latency
I
On-chip state machine to control the SCSI
sequences in hardware
I
Integrated industry standard Fast SCSI-2 core
I
Single-Ended 48 mA outputs to drive the SCSI
bus directly
I
Support for Scatter-Gather DMA data transfers
I
Hooks in silicon and software to enable disk
drive spin down for power savings
General Features
I
Software compatible with AMD’s Am79C960
PCnet-ISA, Am79C961 PCnet-ISA+, Am79C965
PCnet-32, Am79C970 PCnet-PCI register and
descriptor architecture
I
Plug-in and software compatible with AMD’s
PC
SCSI
family of SCSI controllers for PCI
I
NAND Tree test mode for connectivity testing
on printed circuit boards
I
Single +5 V power supply operation
I
Low-power, CMOS design with sleep modes for
both Ethernet and SCSI controllers allows re-
duced power consumption for critical battery
powered applications and ‘Green PCs’
I
Fully static design for low frequency and
power operation
I
132-pin PQFP package
GENERAL DESCRIPTION
The PCnet-SCSI combination Ethernet and 8-bit Fast
SCSI controller with a 32-bit PCI bus interface is a highly
integrated Ethernet-Fast SCSI system solution de-
signed to address high-performance system application
requirements. This single-chip is a flexible bus-master-
ing device that can be used in many applications, includ-
ing network- and SCSI-ready PCs, printers, fax
modems, and bridge/router designs. The bus-master
architecture provides high data throughput in the sys-
tem and low CPU and system bus utilization. The
PCnet-SCSI controller is fabricated with AMD’s ad-
vanced low-power CMOS process to provide low oper-
ating and standby current for power sensitive
applications.