Some times it reads part of the disk. I don't know what it is looking at but it won't format over some types of original data. I've often erased with supper magnet to get past such stuff.
It may also be that is just doesn't support 77 and can only do 80 tracks. Dwight ________________________________ From: cctalk <cctalk-boun...@classiccmp.org> on behalf of Terry Stewart via cctalk <cctalk@classiccmp.org> Sent: Monday, April 17, 2017 4:36:01 PM To: General Discussion: On-Topic and Off-Topic Posts Subject: Re: Extracting files off “unknown” 8 inch disks. Any thoughts… >Here's a writeup for those interested: >http://www.classic-computers.org.nz/blog/2017-04-15- adventures-with-an-8-inch-disk-drive-part1.htm One thing in this project puzzled me. Initially when I was testing the drive I tried to format it for 77-tracks. I used the command FORMAT B: /u /T:77 /N:15 . It wouldn't let me. MS-DOS said " "Formatting 1.15M parameters not supported by the drive" After trying a few other things (unsuccessfully) I just tried a straight FORMAT B: /u It then formatted it without complaint? Listening to the head moving, I counted 77 tracks. The last three tracks the clicking stopped. I'm assuming the head just wrote over that final track 3 times. MS-DOS told me I'd formatted for 1.2MB. I'm puzzled why I couldn't format the disk using the /t:77 and /n:15 switches. Did MS-DOS just go by what was in the CMOS. If that's the case, why have those switches at all? Are they just legacy switches for pre-CMOS machines? Anyone know the answer to this? Terry (Tez) > >
