TESTFDC will by default look at the BIOS setting to determine the drive type, so if you have drives configured correctly for the BIOS it should work. It will prompt you to insert low-density and then high-density (for dual density drives) so that it can test all of the modes and data rates that the drive can support. If you are like me and have a big long cable hanging out of the back that you can connect any drive you like to (or you just want to stuff on another drive to test), and would prefer not the have to keep changing the BIOS, you can test TESTFDC which drive type to test. The available types are: 360 = 300rpm LD 40-track drive (normaly 5.25") 720 = 300rpm LD 80-track drive (either 5.25" or 3.5") 1.2 = 360rpm HD 80-track drive (normally 5.25") 1.44 - 300rpm HD 80-track drive (normally 3.5") eg: TESTFDC A: 360 In all cases, TESTFDC writes only the top 5 tracks of the drive, so you can usually put it on a plain DOS boot disk. - use it for both booting and testing. In my own case, I have a 5.25" HD drive modified with a front panel switch for 300/360 rpm - in the 300rpm setting, it looks like a 720, and in the 360rpm setting it looks like a 1.2 - This lets me test all possible data rates with just the one drive. But you can test all data rates with any combination of a 5.25" HD and any other drive type. Even if you can't test all data rates (ie you have only one drive) send me the results anyway - I simply list the rates not tested as 'N' (not tested). 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