Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!nrl-cmf!ukma!tut.cis.ohio-state.edu!rutgers!att!alberta!ubc-cs!van-bc!root From: lphillips@lpami.wimsey.bc.ca (Larry Phillips) Newsgroups: comp.sys.amiga Subject: Re: Crashing all the way to Kickstart Message-ID: <2223@van-bc.UUCP> Date: 11 Feb 89 17:10:28 GMT Sender: root@van-bc.UUCP Lines: 33 In , armhold@topaz.rutgers.edu (George Armhold) writes: >Could someone briefly explain what is meant by a "bad checksum", >especially in regard to the Kickstart disk? I kinda get the idea that >it means that certain pieces of data are either missing or extra data >has been added to the disk. If this is true, how does kickstart even >load into WCS w/ bad data?? The KS disk has a checksum embedded in it that tells you if the data is good. It is not checked when the KS is loaded, but the data in WCS on a reset is checked, and if the checksum is wrong, it is assumed that a reKick is required. A wild guess atthe rationale for doing things this way is that it makes it easy to test new KS code without having to mess with checksums. ie. a patched KS will load regardless of checksum. A disk of type 'KICK' does not have any checksums on a sector by sector basis, so it will load whatever it finds out there. >PS: How does a "bad checksum" even occur? Is it caused by the same >gremlins that make disks go bad/unreadable?? (ie magnets, etc...) Yes, magnet, dirt, phyical damage, etc. are the main causes of a KS disk going bad. -larry -- Frisbeetarianism: The belief that when you die, your soul goes up on the roof and gets stuck. +----------------------------------------------------------------------+ | // Larry Phillips | | \X/ lphillips@lpami.wimsey.bc.ca or uunet!van-bc!lpami!lphillips | | COMPUSERVE: 76703,4322 | +----------------------------------------------------------------------+