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From: davewt@NCoast.ORG (David Wright)
Newsgroups: comp.sys.amiga
Subject: Re: A3000UX Seems Fated
Message-ID: <1990Dec18.054126.10905@NCoast.ORG>
Date: 18 Dec 90 05:41:26 GMT
References: <39304@nigel.ee.udel.edu>
Organization: North Coast Computer Resources (ncoast)
Lines: 49

In article <39304@nigel.ee.udel.edu> ST402248@brownvm.brown.edu (F. Scott Porter) writes:
>This is the part I was disputing.  Since UNIX only cares about memory
>and disk speed private busses for these things make the issue much
>less straight forward than you are assuming.  I'm not claiming that
	I am aware that Unix really only cares about memory and disk speed
(assuming you aren't doing a lot of terminal I/O, or a lot of graphics which
are going over the bus)
>this is true or not) but that this is not an issue especially on
>most '386DX and '486 machines.  With private memory buses and the
	This is where it is MOST important. You have a quite decent CPU that
is bottlenecked by a very slow, and limited bandwidth bus. Like I said,
MOST 386 systems, IF they are the real 386-DX and not 386-SX will have some
amount of 32-bit memory on a private bus. But almost all of the units I have
seen only support 8 meg on the motherboard, and only provide 1 *proprietary*
slot for more memory expansion. There is NO industry standard for private
busses, and one mfgrs RAM card won't work on another motherboard. And in
almost every case these expansion RAM boards only let you add another 8
meg of RAM, for a maximum of 16 meg without using the slower (and usually 16
bit) bus. There is no way you are going to run 16 users with only 16 meg of
RAM without doing quite a bit of swapping.
>somewhat rare private disk buses one cannot state categorically that
>these DOS based machines have slower I/O throughput.  Since these are
	I never mentioned DOS at all. I am refering strictly to PC clones
with ISA (and EISA) busses running some form of Unix. Someone running DOS
will probobly not even see these things, since they only show up when you have
several programs (and users) running at once. And Windows notwithstanding,
you just don't normally run more than one or two things at a time under DOS.
>the only devices that UNIX really cares about (Other than Ethernet, which
>had a slower bandwidth than either of these buses anyway) if they aren't
	What kind of Ethernet are you using? Even the slowest will do
10 megabits/sec, and you can buy right now boards that will do over 100
megabits/sec. Stick 3 or 4 of these things in an ISA/EISA machine and watch
your performance go down the tubes...
>on the expansion slot bus than the bus is somewhat irrelevant.  Of course
>if you are doing high bandwidth Data collection like I do, you better have
>something better than any of these anyway like direct access dual ported
>memory, etc...
	I don't do any data collection, but I can tell you once you put
more than one or two users on any Unix box you will quickly hit the limits
of the ISA bus, unless you are running terminals at <=9600 (I always use
38400 or faster). There is nothing wrong with using a fast '386 as a
personal workstation, as long as it is just that, personal. Trying to use
a ISA-based system as the heart of a multi-user network is just a waste of
any companies revenues. You would be better of buying a Sun, or a larger
scaleable system like a Sequent or Pyramid and using more terminals.

			Dave

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