Path: utzoo!attcan!uunet!lll-winken!ames!oliveb!sun!pepper!cmcmanis
From: cmcmanis%pepper@Sun.COM (Chuck McManis)
Newsgroups: comp.sys.amiga
Subject: Re: CheapNet
Message-ID: <84395@sun.uucp>
Date: 8 Jan 89 07:31:15 GMT
References: <8901062235.AA12520@jade.berkeley.edu>
Sender: news@sun.uucp
Reply-To: cmcmanis@sun.UUCP (Chuck McManis)
Organization: Sun Microsystems, Mountain View
Lines: 27

[Interesting article deleted, see the reference if you need to refresh
 your memory :-)]

Another suggestion (I know superflouous) why make the Amiga do the 
actual networking? Build a "network tap" out of a Z80, SCC, 2kRAM,
and 2k Eprom. (SCC = Serial Communications Controller). This requires
8 chips, 10 capacitors, 2 resistors, and 1 crystal. Since the serial
controller can talk Appletalk (Apple uses the same one) and the parts
to the whole system cost less than $25 retail you have a good start.
The SCC has two serial ports, make one "appletalk" compatible with the
RJ-11 connector, the other you can connect to the Amiga. Have the 
Z80 handle the CD/CSMA aspects of the network. You may want to replace
the 2k ram chip with an 8k ram chip (32k is also available) that would
raise the price by $5. The Z80 needs only 4 commands available 
SET Address, Send Status, Send Packet, and reset. The latter can be
connected to the DTR line of the serial port for ease of use. 

Since there is some RAM on the "tap" you needn't worry to much about
interrupt latency, and the SCC chip already knows how to do SDLC type
framing so you are pretty much 60% there. 

Final suggestion, don't reinvent the wheel on protocols. Check out
Comer's book or Tannenbaums book on networking and go for it.

--Chuck McManis
uucp: {anywhere}!sun!cmcmanis   BIX: cmcmanis  ARPAnet: cmcmanis@sun.com
These opinions are my own and no one elses, but you knew that didn't you.