Date: Thu, 4 May 1995 13:48:47 +1000 From: Bruce Evans <bde@zeta.org.au> To: mycroft@ai.mit.edu, phk@ref.tfs.com Cc: dyson@Root.COM, hackers@FreeBSD.org, paul@isl.cf.ac.uk, sos@FreeBSD.org, terry@cs.weber.edu Subject: Re: NetBSD supports LBA and large (EIDE) drives Message-ID: <199505040348.NAA00265@godzilla.zeta.org.au>
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>The problems that Hale has noted are entirely on the software end -- Indeed. >LBA mode is not `needed' for IDE drives smaller than 8GB. However: It's not `needed' for IDE drives smaller than 128GB. There are 16 cylinder bits, 4 head bits and 8 sector bits in the IDE interface. The 8GB limit is on the BIOS software end (10 cylinder bits, 8 head bits and 6 sector bits). >1) In practice, the differences between BIOS LBA implementations seem >to be less annoying than the differences between BIOS C/H/S >implementations. I used to think LBA was only a hardware standard for IDE drives. Is there also a software standard for bypassing the C/H/S limits for both ordinary BIOS calls and for booting? >2) There are already 9GB SCSI drives on the market, and the antiquated >C/H/S addressing is not capable of supporting a drive that large. It's interesting that SCSI drives are hitting the 8MB limit at much the same time as IDE drives are hitting the 504MB limit. Bruce
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