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From: wtm@neoucom.UUCP (Bill Mayhew)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Interrupt's for the COM ports on a PS/2 model 50
Message-ID: <821@neoucom.UUCP>
Date: Sun, 6-Dec-87 23:38:47 EST
Article-I.D.: neoucom.821
Posted: Sun Dec  6 23:38:47 1987
Date-Received: Sun, 13-Dec-87 01:04:39 EST
References: <16803@gatech.edu> <132@babbage.acc.virginia.edu>
Organization: Northeastern Ohio Universities College of Medicine
Lines: 25
Keywords: interrupts,serial,com,port,pia
Summary: PS/2 PIC *is* level triggered


Just a few days ago, I has this question and talked to a
knowledgable person as SCO.  He confirmed that in the PS/2
level triggering is used.  Just to keep life interesting, I
suppose.  I have the PS/2 BIOS manual, and don't recall seeing
that documented, but them I haven't finished absorbing every
single word there yet.  He also mentioned relative to the model
80 that if a '387 fpu is installed that the system can hang totally
if a lot of floating point is going on at the same time as a long
DMA xfer (like to disk for instance).  Intel has announced that
this is indeed a bug with the '386 to '387 interface.  Apparently
it can be remedied by the addition of a few SSI gates on some
control lines between the '386 and '387.  How easy it would be to
fix on a model 80, I don't know.  I have used a model 80 owned by
an associate that *does* have a '387 and have not yet seen the
aforementioned bug. (knock on wood...)

Unlike the other PS/2 models, I am impressed with the 80.  It is a
nicely assembled box.  The 70 meg *IBM made* ESDI disk is quite a
screamer too.  Quite a nice product; now if I only had the $$$.
One of the nicer aspects of the 80 is that it doesn't sound like a
miniature wind tunnel next to the desk; in fact it is barely
audible.

--Bill