GoTEK SFR1M44-U100...

Fred Cisin cisin at
Sat Jul 14 23:40:19 CDT 2018

On Sat, 14 Jul 2018, Grant Taylor via cctalk wrote:
> Wow.
> I had no idea that there was a 5¼" disk that held more than 1.2 MB.
> So much history that I'm sure is being lost to time.

Just by going to 10 sectors per track (as Kaypro, Otrona, etc. did), or 
switching to 5 1024 byte sectors,  upped a 360K to 400k, or 720K to 800K.
Talltree Systems (Jlaser, etc.) peddled JFORMAT, to implement 400K on PC. 
Or, if you pushed the head past the spec'd range, to get 41 or 42 tracks, 
. . .

And, in the 3.5" form factor, it was fairly straightforward to tweak the 
parameters of the format to get 1.7M on a 1.4M disk.
Note: to call it "1.44MB" requires creative redefining a MB to be 1024000 
bytes (10^3 * 2^10).

Ensoniq Mirage, and a few others put 5 1024 byte sectors PLUS a 512 byte 
sector on each track for 880K.

There was a Barium-ferrite vertical recording 3.5" ("ED") with 2.8M 
capacity seen occasionally on IBM PS/2.  ("2.88M" in marketing megabytes, 
or 4MB unformatted capacity (which is what NeXt chose to call it))

The "floptical" was 20MB.  Admittedly a change in technology, but the 
floptical drive could also read/write 1.4M disks.
It was usually connected SCSI, not SA400.

LS120 drive also had the 1.4M capability, but the ZIP (100M, 250M?) did 

And, these were just the ones that almost caught on.  At Comdex, you could 
see demos of a lot of amazing stuff that would never be seen again.

There were a variety of 2.5", 2.9" drives.  Some were smaller images of 
720K, but there was at least one with a single spiral track.

Grumpy Ol' Fred     		cisin at

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