Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!ficc!peter
From: peter@ficc.uu.net (Peter da Silva)
Newsgroups: comp.arch
Subject: Re: What is a Mainframe?
Keywords: high-performance
Message-ID: <4445@ficc.uu.net>
Date: 7 Jun 89 21:49:19 GMT
References: <125@ssp1.idca.tds.philips.nl> <20752@winchester.mips.COM> <366@scr1.UUCP>
Distribution: comp.arch
Organization: Xenix Support
Lines: 42

In article <366@scr1.UUCP>, pechter@scr1.UUCP (Bill Pechter) writes:
> In article <4400@ficc.uu.net> peter@ficc.uu.net (Peter da Silva) writes:
> >I was taught that there was a fairly clear distinction between micros, minis,
> >and mainframes:

> A couple of amendments to cover the 1960-1985 minis...

> >	Micro: CPU substantially on one chip.
>         Should be CPU on a chip or "set of chips." 
	No, should be "substantially" on one chip. If the ALU is on a
	single chip that's good enough. But some of DEC's early "micros"
	looked like minis to a lot of people (for example, Cromemco).

> >	Mini: CPU on a single card.
> 	CPU on a card or group of cards.
	Apart from the PDP-8 (which had a rather psychotic architecture)
	what else would you call a mini that had a multi-card CPU? The
	PDP-8s cards were really more like ICs.

> 	Price under $250k for the CPU.
	I don't think price is a good criterion. Inflation remains a
	factor.

> 	Minimum of 8 bit words.
	Not relevant.

> >	Mainframe: CPU on multiple cards.
> 	Minimum 32 bit words.
	What about the early 360s? What about their precursors? They're all
	mainframes. You can come back with the point that any definition that
	includes chips isn't relevant before chips showed up, but that just
	points out that micros had a definite starting point.

The basic thing to consider is that the three classes of machine have different
ranges of real-estate available for non-CPU activities (I/O, for example). This
makes them suited for different classes of problems even if their performance
ranges intersect.
-- 
Peter da Silva, Xenix Support, Ferranti International Controls Corporation.

Business: uunet.uu.net!ficc!peter, peter@ficc.uu.net, +1 713 274 5180.
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