Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!usc!rpi!uupsi!sunic!kth.se!cyklop.nada.kth.se!news From: d88-jwa@byse.nada.kth.se (Jon W{tte) Newsgroups: comp.sys.mac.programmer Subject: Re: System Error: coprocessor not installed -- 2nd post Message-ID: Date: 15 Mar 91 07:24:50 GMT References: <1991Mar14.011721.13837@cs.uoregon.edu> <7161@idunno.Princeton.EDU> Sender: news@nada.kth.se (Mr News) Organization: Royal Institute of Technology, Stockholm, Sweden Lines: 30 In-reply-to: bskendig@phoenix.Princeton.EDU's message of 14 Mar 91 14:23:12 GMT In either case, the message obviously doesn't mean that the program crashed because you don't have a coprocessor installed, because you do have one installed. Thus the error means: something made your machine crash. (As if it wasn't obvious beforehand.) I think this might be an illegal instruction. (line F exception ?) My reasoning: The program goes astray and starts executing data. (This happens... :-) Once it hits data it can't interpret as instructions, you get an "illegal instruction" - BUT words beginning with "A" hexadecimal or "F" hexadecimal generate special exceptions, to allow for extensions in the machine code. A-traps (as they're called) are used by Apple for our loved and cherished toolbox & os, and the F-traps are used mostly for the coprocessor. Now, if you hit upon an undefined F-trap, maybe the ROM resons that "any F-trap is a coprocessor instruction" and issues the "coprocessor not installed" message. One might argue that the ROM could check for the coprocessor (like we mortals should) and change the message to "illegal instructino (unimplemented F-trap)" when it's installed... h+@nada.kth.se Jon W{tte -- "The IM-IV file manager chapter documents zillions of calls, all of which seem to do almost the same thing and none of which seem to do what I want them to do." -- Juri Munkki in comp.sys.mac.programmer