Path: utzoo!utgpu!water!watmath!clyde!att!mtuxo!mtgzz!drutx!druhi!dlm
From: dlm@druhi.ATT.COM (Dan Moore)
Newsgroups: comp.sys.atari.st
Subject: Re: Apple Talk and Ethernet
Message-ID: <3555@druhi.ATT.COM>
Date: 13 Sep 88 14:52:34 GMT
References: <8809120250.AA29256@ucbvax.Berkeley.EDU>
Organization: AT&T, Denver, CO
Lines: 28

in article <8809120250.AA29256@ucbvax.Berkeley.EDU>, BHOLMES@WAYNEST1.BITNET (Brian Holmes) says:
> I have heard about ethernet boards that connect to a MAC via the
> RS232 port, so the hardware is out there.  It would just be a matter
> of writing the software to run it on an ST.  I don't know very much
> about apple talk, but could you then tie a machine on ethernet into
> appletalk?

	There are a couple (at least) of products out that allow you to
connect an AppleTalk Network to Ethernet.  If you did have an AppleTalk
compatible port on the ST you could then hook it to Ethernet.  Of course
the ST doesn't have an AppleTalk compatible port.  Apple used a Zilog
SCC chip that can be run at rates as high as 1 Mega bit per second.  In
the Mac it is limited to about 300K bit per second data rates due to the
hardware design (low clock speed and no DMA to/from the chip). 
AppleTalk is run at about 230K bits per second (I don't remember the
exact figure).  Unfortunately the ports on the ST are limited to low
speeds, 19.2K baud for the serial port and 32K baud for the MIDI ports.
So either you have to modify the ST serial hardware to support higher
speeds or you have to add additional hardware with an AppleTalk
compatible port.  If you want Ethernet it is probably going to be
cheaper to design something to run off the DMA bus instead of going
through an AppleTalk to DMA converter.


				Dan Moore
				AT&T Bell Labs
				Denver
				dlm@druhi.ATT.COM