Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!rutgers!mcnc!ece-csc!ncrcae!ncr-sd!hp-sdd!hplabs!ucbvax!ucsfcgl!cca.ucsf.edu!root From: root@cca.ucsf.edu (Computer Center) Newsgroups: comp.sys.m68k Subject: Re: MC68030 & MC68882 now out and available; comparisons with MC68020? Message-ID: <1068@ucsfcca.ucsf.edu> Date: Thu, 5-Nov-87 19:12:13 EST Article-I.D.: ucsfcca.1068 Posted: Thu Nov 5 19:12:13 1987 Date-Received: Sun, 8-Nov-87 10:45:35 EST References: <4733@elroy.Jpl.Nasa.Gov> <542@amc.UUCP> <3570@ccicpg.UUCP> <2274@mcdchg.UUCP> Organization: Computer Center, UCSF Lines: 32 Summary: USER LEVEL object code compatible is not enough for "drop-in replacement" In article <2274@mcdchg.UUCP>, heiby@mcdchg.UUCP (Ron Heiby) writes: : : I think that the intention of the statement was that it is a drop-in : replacement in the hardware sense *and* in the USER LEVEL software sense. : If you are mucking around with the internal state frames of a chip in : a way that violates the documented ways of using it, then you get what : you deserve. In the same sense, the stack frames generated by (for : example) a BUS ERROR with a MC68030 will differ from those generated by : the same condition with a MC68020. Obey the rules and you won't get burned. : The whole point is that the '030 is USER LEVEL OBJECT CODE COMPATIBLE : with the '020. Ron Heiby seems to suggest that the OS support of these processors may not be compatible but that the new one is still a "drop-in replacement". I think this stretches the terminology in an unjustified way. I take it that the chips are "command level" and "computationally" compatible in their architecture and physically and electrically compatible on the hardware side, but their exception handling and task switching behaviour is different. "Drop-in replacement" implies that if one of the old chips fails in a piece of equipment I can use the new one as a replacement without other changes. Thos Sumner (thos@cca.ucsf.edu) BITNET: thos@ucsfcca (The I.G.) (...ucbvax!ucsfcgl!cca.ucsf!thos) If he says it's "user friendly" watch out; he's a con artist. #include