Return to BSD News archive
Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!news.rmit.EDU.AU!news.unimelb.EDU.AU!munnari.OZ.AU!news.ecn.uoknor.edu!feed1.news.erols.com!news From: mcampbel@erols.com (M. Campbell or Lee Cremeans ) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Installing FreeBSD with two hard drives Date: Tue, 04 Feb 1997 17:21:51 GMT Organization: This house? Are you kidding? Lines: 31 Message-ID: <5d7rbq$c76@boursy.news.erols.com> References: <32EA5951.14C5@pgmstr.com> <32EAE731.2447@worldnet.att.net> <32EB55F2.41C67EA6@mindspring.com> <32EB735F.46E5@worldnet.att.net> <32F0EC95.794BDF32@acm.org> <5ct79t$jou@boursy.news.erols.com> <5d5u9h$emg@uriah.heep.sax.de> NNTP-Posting-Host: man-as5s02.erols.com X-Newsreader: Forte Free Agent 1.0.82 Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:35010 j@uriah.heep.sax.de (J Wunsch) wrote: >mcampbel@erols.com (M. Campbell or Lee Cremeans ) wrote: >> Also, newer BIOSes do SCSI-style cylinder translation for IDE drive >> with >1024 cylinders. >I wonder how they do this given the restrictions of the arguments to >the int 0x13 calls. >Or do you mean IDE drives that do the translation? But that's rather >`olds', even the 40 MB Wester Digital disk in my first AT-class >machine could do this (aged 1990). Still, you'll be restricted to 10 >bits for the cylinder number and 16 bits for the head number in the >int 0x13 call the bootstrap is using. IIRC, they use 8 bits for head, 10 for cylinder and 6 for sector, giving an upper limit of (1024*256*63*512) == about 8GB. The only reason old BIOSes only see 4 head bits is because they didn't need it; IDE and WD1003 controllers only have 4 head bits. They read the params off the IDE drive, either 1) put it in LBA mode or 2) just use the settings it just got, translates the params (usually by doubling the heads and halving the cylinders) and put the translation params in that drive's BIOS parameter table. That way, the BIOS is talking to the drive with the native params, but gives DOS the translation params, just like SCSI. Lee C.