Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!usc!julius.cs.uiuc.edu!apple!portal!cup.portal.com!Chris_F_Chiesa From: Chris_F_Chiesa@cup.portal.com Newsgroups: comp.sys.atari.8bit Subject: Re: CBRN (Crash and Burn) opcode Message-ID: <34182@cup.portal.com> Date: 22 Sep 90 19:19:12 GMT References: <1990Sep19.171649.20159@ingres.Ingres.COM> <5501@harrier.ukc.ac.uk> Organization: The Portal System (TM) Lines: 15 Don't take the title too seriously -- I _DON'T_ have any info on an opcode, per se, but I do know a little bit about the history of opcodes that burn out computers. Whomever mentioned that "it wasn't the opcode, but a memory or hardware address or register that did it" was correct. I believe there was a con- trolling register in the early IBM PC that controlled whether or not the CRT flyback transformer signal was generated and/or actually directed to the transformer itself; apparently it was possible to send a particular control bit value to the register which caused the signal sent to the transformer to become straight DC current, burning out the whole video subsystem. POOF! (I heard something even earlier than this, attributed to the Commdore PET computer, but don't know the details.)