On Saturday 11 October 2008 14:53, Curtis H. Wilbar Jr. wrote: I remember some of those, too, and in fact had some in the files section of my bbs. But I also remember stuff that would deal with "foreign" formats, in particular there was "Media Master" and "Uniform". The former was simply a file transfer program, while the latter would actually "mount" a foreign format disk under an otherwise unused drive letter, both of which I had occasion to use under CP/M. I'm pretty sure that at least MM was available under DOS as well, dunno about Uniform. -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin

I doub't it's because if the number of sectors. ImageDisk has no trouble with 8 sectors - format an 8-sector disk on an old DOS system and try it. Exactly what do you get when you try and use ImageDisk on these disks..? Do you get some sectors, but not others? Does it fail to see any sectors at all? More likely it's because the 8-sector format has other charactistics which make it incompatible with the PC controller. For example, if you are missing one sector of every track, then a likely candidate is that it may squeeze things a little too tightly, moving data into the dead area following the index pulse of the PC controller. If it's only slightly too close, then slowing the drive may help - I've used this technique very successfully to both save and recreate Cromemco disks, which most of my systems can't read on a full speed drive. If you don't see any sectors, or get errors trying to read all sectors, then it may be another factor - perhaps the 8-sector format uses non- standard marks, or a different encoding altogether. Does anyone know the details of the AT&T 3B1 diskette format? What FDC is used in this machine? Regards, Dave -- dave06a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Collector of vintage computing equipment: http://www.classiccmp.org/dunfield/index.html