Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uwm.edu!ux1.cso.uiuc.edu!ux1.cso.uiuc.edu!m.cs.uiuc.edu!marick
From: marick@m.cs.uiuc.edu
Newsgroups: comp.arch
Subject: Re: Is handling off-alignment impor
Message-ID: <3300161@m.cs.uiuc.edu>
Date: 16 Aug 90 13:26:00 GMT
References: <12459@encore.Encore.COM>
Lines: 17
Nf-ID: #R:encore.Encore.COM:-1245900:m.cs.uiuc.edu:3300161:000:617
Nf-From: m.cs.uiuc.edu!marick    Aug 16 08:26:00 1990


>>    As someone who went through a conversion from MVS to MVS/XA I find
>>this perfectly horrible.
> 
> You don't need to wait; the Gould NP line had a lot of compatability
> with the Powernodes; but they did use all 32 bits of address.

One of the easier parts of porting Powernode lisp to the NP was
dealing with the fact that tag bits were now valid address bits.  We
knew how we'd do it well in advance.

Taking advantage of architectural quirks isn't automatically evil.
You just have to weigh the costs against the benefits.

Brian Marick
Motorola @ University of Illinois
marick@cs.uiuc.edu, uiucdcs!marick