Article View: comp.sys.ibm.pc
Article #9252Re: warm/cold reboot on a IBM-PC
From: Risto Lankinen
Date: Mon, 22 Jan 1990 09:42
Date: Mon, 22 Jan 1990 09:42
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Someone (myself being most inexperienced net-user I couldnt check *who*) wrote that the PC reboot was equally succesful either with JMP FFFF:0 or F000:FFF0 . The MS-DOS debugger revealed another JMP FAR in that location, but for *any* Intel-based computer this does not apply. I dont have the relevant Intel specs within reach right now, but I believe I have seen that documented as a difference between different "x":s in 80x86 processor types. So, any ROM code expecting a particular segment preloaded in boot-up will fail if executed with direct jump to an incorrect segment address. (Although IBM BIOSes are not such...) BTW, I have also seen a list of uses for other registers in boot-up as well. Just after reset, certain register(s) in 80x86 (or at least 386) conain information such as CPU version number, microcode checksums etc. I wonder, if any of the processor detection routines around will utilize this stuff... Risto Lankinen --
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arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!uunet!mcsun!sunic!tut!santra!tuura!ristoReferences:
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!uunet!mcsun!sunic!tut!santra!tuura!risto From: risto@tuura.UUCP (Risto Lankinen) Newsgroups: comp.sys.ibm.pc Subject: Re: warm/cold reboot on a IBM-PC Keywords: reboot, IBM-PC Message-ID: <605@tuura.UUCP> Date: 22 Jan 90 09:42:35 GMT References: <203@inesc.UUCP> Organization: Nokia Data Systems Oy Lines: 22