Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!lll-winken!taco!hobbes.catt.ncsu.edu!kdarling From: kdarling@hobbes.catt.ncsu.edu (Kevin Darling) Newsgroups: comp.sys.amiga.advocacy Subject: Re: 8-bit death Message-ID: <1991May10.012512.13688@ncsu.edu> Date: 10 May 91 01:25:12 GMT References: <2945.tnews@templar.actrix.gen.nz> <3474.tnews@templar.actrix.gen.nz> <1991May9.191412.15264@midway.uchicago.edu> Sender: news@ncsu.edu (USENET News System) Organization: North Carolina State University Lines: 14 jcav@quads.uchicago.edu (john cavallino) writes: > As I understand it, the TRAPn instructions were specifically intended by > Motorola to be used to invoke the operating system. Exactly. Even from the original 68K docs: "Some instructions are used specifically to generate traps. The TRAP instruction always forces an exception, and is useful for implementing system calls from user programs." By using Traps as the OS interface, you also don't need to keep OS jump tables around within user space. This can often make it much easier to implement MMU-based OS's, protection, etc. So yep, the ST actually used that feature of the 68K, at least, just as the Motorola gurus had intended. best regards - kevin