Not that it changes anything, but I thought the problem with the density difference was that the lower density drive would put out a stronger signal needed for the less sensitive media, and so the problem with using hd media in a dd drive would be that the dd drive would overdrive the media making a distorted signal?
Is it actually the opposite, that the way they achieved higher density is by using less sensitive media driven by a stonger head? On Sat, Mar 20, 2021, 8:35 AM Jeffrey Birt <bir...@soigeneris.com> wrote: > Oh, sorry I misread what you wrote. But to your point, that could be done. > I use a SuperCard Pro to image floppies which is just a PIC uC with > supporting HW and some spiffy firmware/software. It can image TPDD1/2 disks > easily using a standard 3.5” 1.44MB drive. The software does know how to > interpret the data, it is just a flux map. The .SCP format is well > documented though so one could figure out how to recreate the disk file > structure from it. > > There is a similar device called the Flux Engine that has already done the > file system decoding and can image/interpret TPDD disks using a standard > 3.5” 1.44MB drive. > > > > Jeff Birt > > > > *From:* M100 <m100-boun...@lists.bitchin100.com> *On Behalf Of *Stephen > Adolph > *Sent:* Saturday, March 20, 2021 7:28 AM > *To:* m...@bitchin100.com > *Subject:* Re: [M100] TPDD service manual > > > > not exactly the point I was trying to make. > > pretty clearly a TPDD1 cannot use an HD floppy. > > but a small microcontroller that speaks TPDD protocol and has integrated > FDC function could interface with a modern FDD. > > ..steve > > > > On Sat, Mar 20, 2021 at 8:20 AM Jeffrey Birt <bir...@soigeneris.com> > wrote: > > High density disks, both 3.5 and 5.25, require a much higher flux level to > write. A system designed for DD disks will not be able to write to them > reliably. Some folks have tried HD 3.5” disks in an Amiga or Mac for > example only to find that it reads for a while but after a few weeks or > months it no longer does. You can generally write to lower density disks > with a HD drive. The exception being that it is best to write 360K > 5.25”disks with a 360K drive as the head on these drives was physically > larger and the narrower track written by a higher density drive may not > work well on all 360K drives. > > My take on the TPDD is that it was designed to be cheap (simple) and > portable. Thus, they used a simple 8-bit micro to control everything and > not one of the floppy disc controller ASICs that were available at that > time. But, they wound up with something that would run on AA batteries and > use standard media at the time even if the storage capacity was limited. > > > > Jeff Birt > > > > > > *From:* M100 <m100-boun...@lists.bitchin100.com> *On Behalf Of *Stephen > Adolph > *Sent:* Saturday, March 20, 2021 5:59 AM > *To:* m...@bitchin100.com > *Subject:* Re: [M100] TPDD service manual > > > > this is quite interesting, and nice detective work. > > It would seem like an interesting use case here could be to modify this > firmware to make it target a standard 1.44MB floppy disk drive. > > Maybe it would seem a bit backwards because SD cards are more mainstream, > but still interesting to think about. > > > > I see you have the disassembly in place. > > > >
