Path: utzoo!attcan!uunet!steinmetz!davidsen
From: davidsen@steinmetz.ge.com (William E. Davidsen Jr)
Newsgroups: comp.arch
Subject: Re: Hardware-supported user handlers: examples
Message-ID: <10885@steinmetz.ge.com>
Date: 18 May 88 18:11:46 GMT
References: <353@cf-cm.UUCP> <3095@edm.UUCP> <20618@think.UUCP> <1988May12.162207.16764@utzoo.uucp> <8722@ames.arc.nasa.gov> <10002@tekecs.TEK.COM>
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Organization: General Electric CRD, Schenectady, NY
Lines: 19

The GE600 (Honeywell 6000) vectored the interrupts to a hardware fault
vector, which could then return to the user in user mode if desired. It
wasn't *direct* to the user, but it only needed to be two instructions
away.

The hardware traps were:
  MME (op)		master mode entry
  DRL (op)		derail
  fault tag (address)	special address which would (deliberately) cause
			a restartable fault

GECOS (sic) and CRDOS used the MME to call the o/s, DTSS used the DRL,
and there was a t/s system which used the tag fault. It sent output to
the terminal by evaluating the address of the tally word describing the
string.
-- 
	bill davidsen		(wedu@ge-crd.arpa)
  {uunet | philabs | seismo}!steinmetz!crdos1!davidsen
"Stupidity, like virtue, is its own reward" -me