Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!usc!cs.utexas.edu!csd4.milw.wisc.edu!bionet!ames!pacbell!att!tellab5!rtm
From: rtm@tellab5.tellabs.CHI.IL.US (Roberto Michelassi)
Newsgroups: comp.dcom.lans
Subject: Re: WANTED - pointers to LAN chipsets
Summary: Am7990 LANCE chipset is a good solution
Keywords: LAN chipsets
Message-ID: <1417@tellab5.tellabs.CHI.IL.US>
Date: 30 Jun 89 14:03:17 GMT
References: <1751@softway.oz>
Reply-To: rtm@tellab5.UUCP (Roberto Michelassi)
Organization: Tellabs, Inc., Lisle, IL
Lines: 34

In article <1751@softway.oz> andrewb@softway.oz (Andrew Bettison) writes:
>Consider the following scenario:
>
>	A system containing a very nonstandard proprietary bus
>	populated with all manner of custom-designed cpu, memory and
>	i/o cards.

	[ stuff deleted ]

>Andrew Bettison  andrewb@softway.sw.oz.au  uunet!softway.sw.oz.au!andrewb
>Softway Pty Ltd  ph +61-2-698-2322  fax +61-2-699-9174


Advanced Micro Devices makes a nice (but fairly expensive) LAN chipset.
The base chip is the Am7990 LANCE chip, a 48 pin VLSI device that handles
the transferring and formatting of Ethernet packets to and from memory. The
LANCE is capable of directly accessing memory and can manage lists of data
buffers in memory. Two other chips are required in order to interface to
an Ethernet/Cheapernet LAN. They are the Am7992B Serial Interface Adapter (SIA)
and the Am7995 Ethernet/Cheapernet transceiver.
The LANCE is programmed using several registers and data structures that are
in memory. The LANCE can manage rings of transmit and receive buffers auto-
matically. What this means is that once the chip is initialized, packets are
transmitted or received by simply adding them or removing them from the
appropriate buffer ring.

Another chip to consider is the INTEL 82590/82592 LAN controller. This
chipset is much less expensive than the Am7990 but requires a bit more hardware
and software effort. (An external DMA controller is required and software must
manage the buffers).

I hope that this is some help to you.

							Roberto.