Path: utzoo!attcan!uunet!cbmvax!ditto
From: ditto@cbmvax.UUCP (Michael "Ford" Ditto)
Newsgroups: comp.sys.amiga
Subject: Re: CheapNet
Message-ID: <5641@cbmvax.UUCP>
Date: 7 Jan 89 22:01:47 GMT
References: <8901062235.AA12520@jade.berkeley.edu>
Reply-To: ditto@cbmvax.UUCP (Michael "Ford" Ditto)
Organization: Commodore Technology, West Chester, PA
Lines: 47

In article <8901062235.AA12520@jade.berkeley.edu> CRONEJP@UREGINA1.BITNET (Jonathan Crone) writes:
>I would like to build a network by tieing the transmit line of each system
>to the receive line  of the next system in line, thus forming a
>ugly looking ring network.
>
>The hardwrae handshaking would be handled by connecting the
>RTS line of the sending system to the CTS line of the receiving system...

That's been done, and should work OK.

>the receiving system would receive the packets, see if its for it, and
>if it isn't send it on.

Sounds OK, but the send-it-on criteria should include checking to see if
the packet ORIGINATED from the current node, and discard it if so.
Otherwise, sending to a node that is not connected will result in an
infinite loop.  If this is done, the first criteria could be eliminated,
resulting in an ethernet-like "broadcast" network.

>the idea is that access to the network would be as such,
>
>NET:0/df0:foo/glar/spam

>now for my questions. obviously i have to write a device driver
>for this thing. Now, does this device driver have to grab the serial port
>directly? or can it talk to SER:

I would recommend putting off the NET: handler for a while, seing that
filesystem handlers are among the more obscure aspects of Amiga system
programming.  For example, you could first make a lower level device that
allows sending a packet to a particular named port on a particular node.
When that is working, you can make your NET: handler use the lower level
net mechanism.

The first step doesn't require writing a device driver at all; you could
just have a message port to which processes could send requests.  Making
that a library or device might be a good idea, though.

You could probably do all the necessary serial port access through the
serial.device.  Using SER: would be difficult.
-- 
					-=] Ford [=-

"The number of Unix installations	(In Real Life:  Mike Ditto)
has grown to 10, with more expected."	ford@kenobi.cts.com
- The Unix Programmer's Manual,		...!sdcsvax!crash!elgar!ford
  2nd Edition, June, 1972.		ditto@cbmvax.commodore.com