Path: utzoo!attcan!uunet!munnari!otc!metro!pta!teti!nswitgould!nick
From: nick@nswitgould.OZ (Nick Andrew)
Newsgroups: comp.os.minix
Subject: Protocols (was Re: What to do with rs232 on Minix-ST)
Message-ID: <10239@nswitgould.OZ>
Date: 9 Jan 89 14:35:41 GMT
References: <1853@ast.cs.vu.nl>
Organization: Comp Sci, NSWIT, Australia
Lines: 41

in article <1853@ast.cs.vu.nl>, ast@cs.vu.nl (Andy Tanenbaum) says:
| 
| I haven't seen any. The reason I didn't mention X/YMODEM in the book probably
| has to do with the fact that I don't have the foggiest idea of what 
| (it is)/(they are). I know about uucp, kermit, X.25, 802, and OSI.  Does this
| supersede any of these?  I hope it supersedes OSI, because that is the one
| most in need of being superseded.  For MINIX, I suspect kermit is going to be
| the standard file transfer mechanism (other than the Amoeba networking for
| people with Ethernets).  Kermit is available on all known machines, and the
| MINIX version seems pretty stable and reasonably efficient.

	I suspect Kermit is NOT going to be the standard file transfer protocol
for Minix, unless it is talking to some of the less capable (comms-wise)
mainframes. The standard for the personal computer world has been based around
Xmodem, Ymodem, Sealink, Zmodem, etc... for some years now. 

	As much as I respect the Kermit protocol (and I _do_ respect it),
it is an inefficient protocol, and does not make full use of Minix's serial
capabilities. As a non-streaming protocol, it is slow compared to those
protocols mentioned above.

	I have ported Zmodem to Minix. This required trivial changes to the
ioctls setting up the tty1 device. In terms of line utilisation, it seems
to achieve nearly 100% utilisation on receive, and about 97% on transmit.
(Note these figures are estimates).

	I am in the process of porting Sealink to Minix. This is a less
trivial task, as Sealink was designed for the PC world, whereas Zmodem was
designed to be portable over several flavours of Unix. Sealink being a
streaming protocol like Zmodem, should achieve close to 100% line
utilisation with little overhead, and no propagation time delays.

	By all means, let's keep Kermit, but I don't feel there is a need
to make it the "standard".

Regards to all, Nick.
-- 
			"Zeta Microcomputer Software"
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