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From: edp367s@monu6.cc.monash.edu.au (Rik Harris)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: second serial port
Keywords: 2232 7 port
Message-ID: <1990Dec3.053356.26826@monu6.cc.monash.edu.au>
Date: 3 Dec 90 05:33:56 GMT
References: <14383@crdgw1.crd.ge.com> <90334.151404DXB132@psuvm.psu.edu> <1990Dec2.141048.10108@NCoast.ORG>
Organization: Monash University, Caulfield Campus
Lines: 43

davewt@NCoast.ORG (David Wright) writes:

[commodore & IBM board details deleted]

>	I would never use a board with more than 2 ports on it if it didn't
>have it's own CPU. The only time a "dumb" board is worth the CPU overhead is
>if you are running only low-speed devices, or you just want to be able to
>attach 2 or three printers, and leave them attached rather than getting a
>switch box. If you try to run 3 or 4 terminals at 9600 baud without a CPU
>on the I/O board you will see significant speed loss.

>		Dave

[I have not used any of the multiple serial boards on any machine]

I dont know what level of hardware expertise you have, David, but your
comment is rather confusing.

A CPU will add convenience to the design of a piece of hardware, not speed.
A CPU needs to be clocked, and must access memory, and the hardware is
limited by the speed the CPU can run at.

For the last year I have been working on a Packet Switching Local Area
Network (what it is/does is not really relevant) that is pushing away
from the CPU, because it is too slow.  We have built specialised
circuits to have the hardware do all the buffering and switching of
packets without CPU intervention.  Doing this, we have increased the
potential speed of the device by ORDERS OF MAGNITUDE (more than 3
orders).

Now, I'm not saying that a product that doesn't have a CPU is _going_
to run much faster, just that there are more things to consider than
simply whether the product has a CPU on it or not.  Admittedly, the
product that can handle 3-4 terminals at 9600bps, that is on the
market first, would probably be one with the CPU, but it is still not
necessarily the best.

Rik. 
-- 
Rik Harris - edp367s@monu6.cc.monash.edu.au           | Build a system that
new address!  rik@sola.fcit.monash.edu.au             | even a fool can use,
Faculty of Computing and Information Technology,      | and only a fool will 
Monash University, Caulfield Campus, Australia        | want to use it.