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Path: utzoo!watmath!clyde!bonnie!akgua!mcnc!decvax!wanginst!ucadmus!harvard!seismo!brl-tgr!tgr!cottrell@nbs-vms.ARPA
From: cottrell@nbs-vms.ARPA
Newsgroups: net.unix-wizards
Subject: vax compatibility mode mark
Message-ID: <8276@brl-tgr.ARPA>
Date: Tue, 12-Feb-85 11:36:53 EST
Article-I.D.: brl-tgr.8276
Posted: Tue Feb 12 11:36:53 1985
Date-Received: Sat, 16-Feb-85 05:53:11 EST
Sender: news@brl-tgr.ARPA
Organization: Ballistic Research Lab
Lines: 15

/* Henry Spencer writes...
> Actually, a friend who got one of the first 780's outside DEC, and had
> DEC people working with them for a while getting it running, mentioned
> one other thing that compatibility mode doesn't support:  the MARK
> instruction.  This omission is (I believe) undocumented, but it's not
> surprising that nobody has noticed the absence of the most useless
> instruction ever added to the 11...
> -- 

It's WORSE than useless. I suspect the reason DEC shyed away from
supporting separate I/D in space in RSX etc. is that it won't work with
mark. Mark executes off the stack! Somebody goofed royally. 

	jim
*/