Yeah that does sound strange. And I agree, the drive 'should' switch based on the hole in the disk. Does it format to 720 or 1.44 when the hole is covered?
On Mon, Mar 25, 2019, at 7:37 AM, Stephen Adolph wrote: > Kurt, agree with everything you have said. > > The odd thing is- > > * using an HD disk in an DD/HD drive, and covering the hole with tape, would > seem to be BAD > ---> because you are telling the drive to use the wrong current settings for > the actual disk media. > > However, this is apparently the way to make my system functional. > > so, strange. I would have thought it would be the opposite - let the drive > decide what current to use, matched to the "cookie". > > > On Mon, Mar 25, 2019 at 10:19 AM Kurt McCullum <ku...@fastmail.com> wrote: >> __ >> The magnetic coercivity on HD disks is different than on regular disks. It >> requires more energy to lay down the tracks. If you start with a blank HD >> disk rather than a pre-formatted disk then you have a better chance. That's >> because once the HD tracks are laid down, you need to erase them for your >> new format. If your drive doesn't have enough energy to completely erase the >> existing track, it wont work. 720k disks have a lower coercivity and >> therefore work with either a 720k or 1.44mb drive. A 1.44 drive has a sensor >> for the open hole and when it sees that hole, it will use a higher level of >> write energy to properly work with the media. When that hole is covered, it >> will use a lower level which is what the 720k media is looking for. Though I >> do remember that formatting a 720k disk in a 1.44mb drive didn't always work >> when going back to a 720k drive. >> >> Not sure about the Coco drive, but my TPDD2 does not work reliably with HD >> disks. I have only been able to format one properly and it had data failure >> shortly after. >> >> Kurt >> >> On Sun, Mar 24, 2019, at 6:32 PM, Stephen Adolph wrote: >>> interestingly, >>> >>> Yes, if I take an HD disk, and tape over the hole to make it appear to be a >>> DD disk, then it works. >>> >>> But why? >>> >>> the floppy is capable of both formats... >>> >>> On Sun, Mar 24, 2019 at 7:39 PM Mike Stein <mhs.st...@gmail.com> wrote: >>>> __ >>>> Have you tried closing the HD sense hole with a piece of tape or similar? >>>>> ----- Original Message ----- >>>>> *From:* Stephen Adolph <mailto:twospru...@gmail.com> >>>>> *To:* m...@bitchin100.com >>>>> *Sent:* Sunday, March 24, 2019 6:08 PM >>>>> *Subject:* Re: [M100] question regarding floppy disks. >>>>> >>>>> the Coco is using it's standard controller >>>>> >>>>> When issuing the DSKINI 0 command the coco tries to format for 180kB. >>>>> >>>>> The combination of >>>>> (Coco, std controller, PC 1.44MB drive + a 720kB dd floppy) works >>>>> >>>>> whereas >>>>> (Coco, std controller, PC 1.44MB drive + a 1.44MBB hd floppy) does not >>>>> work >>>>> >>>>> this is something I don't understand! >>>>> >>>>> >>>>> >>>>> On Sun, Mar 24, 2019 at 5:42 PM Gregory McGill <arcadeshop...@gmail.com> >>>>> wrote: >>>>>> likely the floppy controller doesn't support 80 tracks or high density.. >>>>>> most of the controllers of the era are ds/sd 40 track or dsdd 40 track.. >>>>>> are you able to format 720k? ds/dd 80 track? >>>>>> >>>>>> Greg >>>>>> >>>>>> On Sun, Mar 24, 2019 at 2:38 PM Stephen Adolph <twospru...@gmail.com> >>>>>> wrote: >>>>>>> I'll start by saying this isn't an M100 or TPDD discussion, but just >>>>>>> looking to understand something. >>>>>>> >>>>>>> I have a Tandy Coco3 with a 3.5 inch floppy drive. The drive is a >>>>>>> standard PC drive and it is working well. >>>>>>> >>>>>>> Seems though that I cannot use 1.44 MB floppies in that drive. They >>>>>>> don't seem to want to format. >>>>>>> >>>>>>> I really don't understand where the problem could be. >>>>>>> - the drive and the floppy are compatible >>>>>>> - the disk is known good and formats at 1.44MB in a PC >>>>>>> - if it can support 135 TPI, why can't it support 35 TPI? >>>>>>> >>>>>>> Does anyone know what's going on? >>>>>>> >>>>>>> thx >>>>>>> Steve >>
