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From: stever@cit-vax.Caltech.Edu (Steve Rabin  )
Newsgroups: comp.sys.m68k
Subject: Re: move sr/move ccr: crock
Message-ID: <1560@cit-vax.Caltech.Edu>
Date: Thu, 22-Jan-87 04:24:57 EST
Article-I.D.: cit-vax.1560
Posted: Thu Jan 22 04:24:57 1987
Date-Received: Thu, 22-Jan-87 20:16:33 EST
References: <809@imagen.UUCP>
Reply-To: stever@cit-vax.UUCP (Steve Rabin  )
Distribution: na
Organization: California Institute of Technology
Lines: 13
Keywords: read the manuals

In article <809@imagen.UUCP> geof@imagen.UUCP (Geoffrey Cooper) writes:
>My question is why the lords of 68k-land did this?  Presumably
>there is some lack or portability or security loophole in allowing
>a user program to look at the SR.
>
>- Geof Cooper
>  IMAGEN

Motorola did this to facilitate debugging new operating systems.
When the system under development reads the SR, a trap is generated,
allowing the debugger to lie about status bits to the proto-OS.

                                           Steve Rabin