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From: ralphw@ius2.cs.cmu.edu (Ralph Hyre)
Newsgroups: net.micro
Subject: Re: IBM RT: first impressions
Message-ID: <296@ius2.cs.cmu.edu>
Date: Fri, 7-Feb-86 23:38:39 EST
Article-I.D.: ius2.296
Posted: Fri Feb  7 23:38:39 1986
Date-Received: Wed, 12-Feb-86 07:27:35 EST
References: <1400012@orstcs.UUCP>
Organization: Carnegie-Mellon University, CS/RI
Lines: 25

In article <1400012@orstcs.UUCP> nathan@orstcs.UUCP (nathan) writes:
>memory additions come in 2Meg chunks and there's only room for two
>memory cards.  It uses a PC-AT peripheral bus (it's not clear whether
>memory rides there too) where disk controllers, graphics boards,
>and network interfaces go.

RT-PC memory sits on the fast (RT-only) bus, but the disk controller sits on
the AT bus.  Current versions of the disk system don't provide for DMA,
apparently due to the I/O Channel Controller not being able to request DMA
through the Memory Management unit.  Everybody here is saying that IBM used
a fairly conservative technology (2-micron NMOS) for the RISC chip, so
future performance enhancements are possible/likely.  The RT bus and RISC
chip are designed to support multiple processors (bus has TAG bits to identify
the device a request came from, and processor has set & test bit instruction)
It appears to be a well executed machine - Sun and company are probably 
worried about the RT-PC-2

It's too bad the put the keyboard's escape key in the wrong place again,
it lives up there among the function keys, above the main keyboard.
-- 
					- Ralph W. Hyre, Jr.

Internet: ralphw@c.cs.cmu.edu (cmu-cs-c.arpa)	Usenet: ralphw@mit-eddie.uucp
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