Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!evax!cs4344af From: cs4344af@evax.arl.utexas.edu (Fuzzy Fox) Newsgroups: comp.sys.cbm Subject: Re: 1581 Autoboot Bug? Message-ID: <1990Nov30.044152.531@evax.arl.utexas.edu> Date: 30 Nov 90 04:41:52 GMT References: Organization: Computer Science Engineering Univ. of Texas at Arlington Lines: 27 In article lcs@tangerine.rutgers.edu (Lyle C. Seplowitz) writes: > What is this about the 1581 having an autoboot bug? The "bug" is just a misunderstanding about the way the drive "should" operate when it performs a Validate command. A Validate, as everyone knows, frees up all the blocks on the disk, then rebuilds the BAM by following the sector links in all files on the disk. Unfortunately, this will cause a boot sector at track 1, sector 0, to be freed up, and overwritten when a file reaches that sector. So a disk that is validated and used to autoboot will suddenly stop booting after a file is saved to it some time in the future. Commodore knew this would happen when they produced their Test/Demo disk, so to "fix" the problem, they created a dummy file and pointed it to track 1, sector 0. Unfortunately, Validate wants to follow the sectors in this "file" and generates an illegal track/sector error, which means that you can't validate the Test/Demo disk. However, as someone pointed out, the 1581 has a unique feature to get around this "bug." Simply create a partition that includes track 1, sector 0, and Validate will happily ignore this partition, but not free it up as it usually would. This solves the problem quite well. Unfortunately, 1541/71 owners can't do anything about this problem, and so they must either avoid validating disks with boot sectors, or remember to re-allocate the sector after validating.