From: "Vintage Computer Festival" <vcf at siconic.com> Sent: Sunday, May 01, 2005 5:15 PM Every disk drive has a unique alignment, this means that one drive can read/write disks created on it but may have problems in another drive. You can make slight a slight alignment adjustment and see if the errors are worse or not. If the errors are worse move alignment the other way. "Gap in sectors" refers to Anadisk assuming that there are missing sectors, this can happen when data is misread and Anadisk believes there is an odd sector number. Having a disk drive "perfectly" aligned does not mean you can read all disks, if the disk was written with a mis-aligned drive and you need to read the data then you must adjust your drive to closely match the original drive. Recovery can also be done with multiple drives where some drives can read some tracks but not others, later the track data can be cut and pasted together. Even after aligning a drive it will still be unique for numerous reasons. Alignment refers to setting many mechanical adjustments on a drive to optimized tolerances, on two sided drives you need to offset each head off-center of tolerance to average them to optimized alignment. Alignment is generally based on adjusting track 00 and the center of the disk, this means that the last tracks are least likely to be within tolerance. As stated above the problem can be either your drive or the original drive but the result remains the same. If you must read the disk you can play with the drive but be careful you may not be able to restore the drive without the proper alignment disks & tools. Randy www.s100-manuals.com

Rmemeebr that the last tracks are physically shorter, which means the bit density is higher on them. So if there's anything marginal -- a worn head, slight misalignment, etc -- it'll show up there first. IIRC, it means it found, say, sectors 0, 1, 2, 4, 5, 6, 7, 8. It never found a sector numbered 3. This might be right (it's perfectly possible to format a disk like that), but often it means the sector header was unreadable. One thing to check is if the total number of sectors is the same on all tracks. For most systems (that can be read by a PC controller) it will be, so if you get the 'Gap in Sectors' message and there's one fewer sector found, it's almost vertain it didn't manage to read that sector header. If it was mine, I'd do the full set of tests on the drive, which would mean buying an alignment disk. And 8" alignment disks seem to be particularly expensive. -tony