19 May
2005
19 May
'05
5:55 a.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org
[mailto:cctalk-bounces at classiccmp.org] On Behalf Of Rob O'Donnell
Sent: Thursday, May 19, 2005 4:04 AM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: mini versus micro?
At 20:08 18/05/2005, Ethan Dicks wrote:
I'm pretty sure there's no minicomputer class of system anymore. I
believe
there are systems referred to as "Entry level", "Enterprise",
"Mid-frame",
and "Mainframe"
I agree here though, it's all marketing. The only actual distinction you
can make hardware-wise is between microprocessor and non-microprocessor
based systems...a good example of this is DEC, who called every QBUS machine
a microcomputer.
I believe the proof in the pudding here is that there are now hundreds of
owners of "personal minicomputers" and even a few with "personal
mainframes."
There was some strange crossover material here too, like 1973's GT40
graphics workstation, which sat on a desk, and had its own CPU and whatnot,
that it shared with the 11/05...however, the 11/05 model was designated as a
minicomputer, even though some of the lowest end 11/05 models ran a single
user programming system off cassettes...if that's not a "personal
computer"....I don't know what is.
So to recap, in marketing terms, a personal computer is:
A computer architecture designed with a single user *in mind*.
A minicomputer is an architecture with a multiuser system in mind.
A mainframe is an architecture with a large number of multiple users in
mind.
How can I illustrate the difference between mainframe and mini? Back in the
day, I know there were some businesses that ran each of their engineering
areas each on a different mini, then the finance on another, administration
on another, etc. I honestly believe the marketing of the minicomputer to be
only groundbreaking in that it was the first step toward decentralized
computing...again, that's only *marketing* wise.
Of course, if you're DEC, you don't know what you're selling, so it's all
moot ;)
End rant :D
Julian
On 5/18/05, Rob O'Donnell
<classiccmp.org at irrelevant.fsnet.co.uk> wrote:
> The worst processor/user ratio I think I
encountered was about 50
> users sharing a 486dx50.. It was in a rack case, in the
top 6" of a
> 4' rack, the rest being blocked in empty
space except for
a UPS sat
> in the bottom. The users most definitely
called it "the
mainframe" !
Worst processor/user ratio for PeeCee-class equipment, or on a
per-cycle basis?
I was thinking specifically of the PeeCee based stuff. I did
have for a while an ex-customer "Microfive" machine, 8088
based, 12 serial ports on the back, no kb or video, and not
PC architecture. With maximum users that would have been worse...
Thinking about it, though, some of the VAX (11/780) and
own-brand machines I used years back at Ferranti would have
been far less cycles/user.
[snip]
So in the great mini-vs-micro debate, once one is
talking about later
16 and 32-bit minis (early 12 and 16-bit minis do tend to have one
medium-performance I/O bus), I'd have to say that I/O
architecture has
as much to do with the definition as the number of
processors.
I think the micro/mini is a pretty hard distinction to make
when talking about current hardware; the technologies
cross-pollinate! Even in old stuff, it certainly sounds like
it's more of a marketing term rather than a technical
definition - The "small enough for a department to afford"
meaning of mini feels best to me for the older machines.
Rob