Date   : Sun, 01 Nov 2009 21:07:34 +0000
From   : jgh@... (Jonathan Graham Harston)
Subject: Econet packet size

Rick Murray wrote:
> enabled to receive that data. A packet contains at least one byte, and
> at most 1280 bytes, of data.
> --8<--------
> Source: http://mdfs.net/Docs/Comp/Econet/RISCiX.txt
 
> It is an undocumented Acorn document. RISCiX is an ARM based system that
 
It should be dated about 1989/1990-ish. I'll have to dig out the
original photocopies and see what it says.
 
> was, I believe, a Unixy contender to RISC OS that never quite caught on.
> The Rxxx workstations (looking a lot like souped-up A440s to me!). That
> would date it late-80s. I would imagine the 1280 is likely a limitation
> of the 6502-based machines, >1K is a lot in a 32K computer! At any rate,
 
There is no limit to an Econet packet. That comes out of the fact
that an Econet packet has a start indicator and an end indicator,
and not a fixed size or a length indicator.
 
Early versions of *VIEW used a single 20K packet to transfer MODE
0/1/2 screens. Later versions use packets up to 8K. The 1280
refered to in the RISCiX document is a limit imposes /for/ /that/
/discussion/, not a limit imposed by the hardware or the protocol.
If you read later on you will also see a discussion on the limits
on broadcast packets and packets that will travel through a bridge.
While any Econet packet can be infinitly long, limits are
neccessarily imposed by the transmitting and receiving /programs/.
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
/* Real programmers don't use comments. */