Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!samsung!olivea!uunet!lll-winken!sun-barr!cronkite!newstop!sun!amdcad!brahms!phil From: phil@brahms.amd.com (Phil Ngai) Newsgroups: comp.sys.ibm.pc.hardware Subject: Re: How to access all of a 676MB ESDI Seagate/WREN under DOS 5 ? Message-ID: <1991Jun25.212337.11896@amd.com> Date: 25 Jun 91 21:23:37 GMT References: <1991Jun17.124112.9416@ufhx1.ufh.ac.za> <173@thor.sdrc.com> Sender: usenet@amd.com (NNTP Posting) Organization: Advanced Micro Devices, Inc. Lines: 21 scjones@thor.sdrc.com (Larry Jones) writes: >The problem with more than 1024 cylinders is that DOS uses the >BIOS to access the disk and the BIOS interface only allows 10 >bits for a cylinder number. This is an unfortunate fact of life. >Since this is an interface problem, there is nothing that either >DOS or the BIOS can do to avoid it -- both must agree on any >change. Since most BIOSes are in ROM, this is a nasty problem. >The only reasonable way to fix this is for DOS to completely >avoid the BIOS and access the disk hardware directly, but that >means that DOS must now become much more complex since it will >have to be intimately familiar with every existing disk >controller, as well as future controllers. This is mostly true, but why couldn't the disk controller vendors supply a DOS device driver which implements a standard interface for accessing 11-bit cylinder numbers? This would get loaded in config.sys, Microsoft could have a stable interface to write DOS to, and the disk controller vendors would have an important selling point. -- If your son's dentist had AIDS, would you want to know?