Looking at this picture it indicates the disk is 406TPI which is significantly higher than the 96TPI used with 1.2MB HD drives. Also from Wiki: 2TD drive in NEC PC-88 VA3 3 1⁄2-inch TD 1988 ca. 9.3 MB 12.5 MB[13] (13 MB unformatted) -Ali

On 3/28/23 17:03, Fred Cisin via cctalk wrote: Unfortunately, we're stuck with the terminology. We probably should call them 2.0 megabyte floppies (at 500Khz, you can fit 12,500 unformatted 8 bit bytes on a track, so 12,500*2*80 = is exactly 2,000,000 bytes. Or, as the young clerk at the Fedex counter asked the other day, "What's a floppy disk?". Yes, Fred, we're THAT old. --Chuck

On 3/28/23 18:06, Fred Cisin via cctalk wrote: The shipment that was being returned via Fedex, was, in fact 70 8 inch diskettes, ca. 1983--all read just fine. I guess that's a concern for our current removable media, be it Blu-ray DVD, USB pen drive, microSD card, or cloud. I wonder how much of that will still be accessible after 40 years. Or if it will matter... --Chuck

On Tue, 28 Mar 2023, Ali via cctalk wrote: Not quite the same way as recording 720K on 1.2M drive. Far more than you wanted to go through: 720K on a 1.2M drive is using all 80 tracks, but recording each track at the density used by 360K drives. a 360K drive, in PC format, has 9 512 byte sectors, for 4,608 bytes per track, plus sector headers, gaps and other overhead.. About 6.25K unformatted capacity. Other disk formats, with different number of bytes per sector and/or sectors per track can haveup to 5120 bytes of data per track (5 x 1024). It normally does that by using 250,000 bits per second at 300RPM. Some 1.2M drives switch back and forth between 300 RPM and 360RPM. If the drive is at 300 RPM then you need 250,000 bits per second to do 360K, or "720"/"QD". If the drive is at 360RPM, then you need 300,000 bits per second. 360K on a 1.2M drive is double stepping, to get 48tpi, and using 250,000bps at 300 RPM, or 300,000bps at 360RPM 1.2M is typically 15 512 byte sectors, with 360 RPM and 500,000 bits per second. 8"DD is the same. What NEC did was to have 8 1024 byte sectors as their format on their 8"DD and 5.25" HD disks, with the usual 360RPM and 500,000 bits per second. 8 x 1024 gives slightly more capacity then 15 x 512. "1.4M" is usually 18 512 byte sectors, with 500,000 bits per second at 300 RPM. But, THEN what NEC did differently than everybody else, is that they sped up their 3.5" drives to 360 RPM, so that they had the same format on their 3.5" disks as on their 5.25"HD and their 9"DD. A "mode 3" 3.5" drive needs to be able to do both 300 RPM for "1.4M", AND be able to do 360RPM for the NEC format. "SD"/"Single Density" is FM. There is a clock pulse and a data pulse for 1, and a clock pulse and gap (no pulse) for a 0. So, there are two pulses (or a pulse and a missing pulse) for each bit. Some engineers call that "half density" "DD"/"Doble Density" is MFM. MFM permits almost twice as much data to be crammed into the same space. It does that by leaving out the clock pulse when it is between two data pulses. Since you, therefore, won't have continuous clock and data pulses, the distance between pulses is almost double, permitting using a higher data transfer rate, for almost twice as much data per track. The marketing people called that "double density", and AFTER they started doing that, they began to refer to FM as "single density". Therefore, the term "double density" first occurs in the literature BEFORE the term "single density" was ever used (much like "World War 2" occured in newspapers of the time, BEFORE anybody ever called the previous one "World War 1") "HD"/"High Density" is MFM. Improvements in hardware and media made it so that you could get away with twice as much data per track. It is ACTUALLY just "double density", with twice the data rate. "ED"/"Extended density" is MFM. Use of barrium ferrite media and perpendicular recording permitted squeezing more. It is 1,000,000 bits per second. 8" is 48tpi, with an unformatted capaciy of 500K SS or 1M DS "360K" 5.25" is 48tpi, with an unformmatted capcity of 500K. "1.2M" is 96tpi, with an unformatted capacity of 1.5?M "720K", "1.4M", and "2.8M" are all 135 tracks per inch "720K" has an unformatted capacity of 1M "1.4M" has an unformatted capacity of 2M "2.8M" has an unformatted capacity of 4M The disk that you linked a picture of says "406TPI"! Therefore, it presumably has about three times as many tracks. (240?), which, if it does a 1,000,000 bits per second, with track density the same as "2.8M", would give it an UNFORMATTED capacity of 12M, and a formatted (data) capacity of about 8.5M. A "TD" drive, if it also handles "720K"/"1.4M" would need both types of heads, and be able to handle both 135tpi and 406TPI. And the FDC would need to do 250,000 bps, 500,000 bps, and 1,000,000 bps. -- Grumpy Ol' Fred cisin(a)xenosoft.com

That should read "density within each track", as "track density" could mean how close the tracks are to each other, and this is one third the track to track distance.

Chuck, Yep, that the one. No interest in collecting. I am just surprised it didn't catch on assuming cost of drive and media wasn't atrocious. In 1989 I was still using a 5160 w/ a 10MB HDD (in fact I ran Win 3 on that machine with a NEC CPU upgrade). Having an almost formatted capacity of 10MB, on even a $10 floppy disk, would have been phenomenal. That’s why I am surprised these floppy alternatives did not catch on especially when the ZIP drive took over the market like wild fire without even offering backward compatibility.... From what I understand the Caleb was too little too late. Zip had already established dominance and LS120 was on the market. Well when the first generation becomes known for mangling your data.... I blame Sony and poor execution for that one. If they had done it right a 200MB 3.5" disk drive in the late 90s would have still been awesome especially since it had backwards compatibility. I think the same can be said of the LS240 drives half a decade sooner in introduction and they would have taken over everything. -Ali

On 3/29/23 08:36, Chuck Guzis via cctalk wrote: Forgot to mention: The attraction for the Caleb drive was price. The disks retailed for $5 the each. One problem that I've noticed is that the drive doesn't play well on a PATA bus.Regardless of setting for master or slave, very often if there's another device on the bus, the Caleb will either disappear itself or the bus will hang. When the drive works, it works well. Eject is mechanical, so no issues with a powered eject. All in all, I think the reason the Caleb failed with market penetration is that it was woefully underfunded. --Chuck