Path: utzoo!utgpu!attcan!uunet!cbmvax!rutgers!mailrus!cornell!batcomputer!riley From: riley@batcomputer.tn.cornell.edu (Daniel S. Riley) Newsgroups: comp.sys.amiga.tech Subject: Re: Request to Commodore (Bad Blocks) Keywords: trackdisk.device Message-ID: <6392@batcomputer.tn.cornell.edu> Date: 23 Sep 88 18:04:23 GMT References: <8891@cup.portal.com> <5660018@hpcvca.HP.COM> <40244@linus.UUCP> Reply-To: riley@tcgould.tn.cornell.edu (Daniel S. Riley) Organization: Cornell Theory Center, Cornell University, Ithaca NY Lines: 29 In article <40244@linus.UUCP> eachus@mitre-bedford.arpa (Robert I. Eachus) writes: [somebody else wrote this, but the attribution has gotten lost. *sigh* ] >> * DO NOT CHANGE THE WAY YOU READ. ONLY CHANGE THE WAY YOU WRITE. * >>Therefore READS TAKE THE SAME AMOUNT OF TIME whether the writes are >>decoupled from the index pulse or not. >>We gave up track reliability for at best a 7% increase in overall >>floppy speed. > Not quite, Charles, adding track reliablity won't cost even that >much. Right now, trackdisk.device must rewrite an entire track even if >only one sector is changed, and more important must read a track >completely to write one sector. If a "smart" trackdisk.device knows >where sectors are located, it can do single sector writes in an >average of 0.7 rotations, instead of 2.2. I was under the impression that you could not do single sector writes without increasing the inter-sector gaps, which would mean giving up a sector/track. As it stands now, there is not enough space between sectors to reliably place the heads for a single sector write. Wasn't the extra space part of the point of having a trackdisk.device? Also, I would think you would want to sync reads to the index mark when you are trying to recover sectors from a damaged track. Otherwise, you have to rely on ferreting out where the track starts from damaged information, which seems a lot less reliable than knowing where on your damaged track the sectors should be. -dan riley (dsr@ln61.tn.cornell.edu, dsr@crnlns.bitnet) -wilson lab, cornell u.