3 ms·

> Modified frequency modulation (MFM) is a run-length limited (RLL) line code So floppies are RLL too. If you look at the end of the table[0], you will see wh

> Modified frequency modulation (MFM) is a run-length limited (RLL) line code So floppies are RLL too. If you look at the end of the table[0], you will see what a practical limit increased with SuperDisk in '96/97 and the actual floppy (ie not a separate standard with the same dimensions) capacity increase was achieved only at the end of 2000 [1] when nobody cared about floppies as a means to move "massive" amounts of data. [0] https://en.wikipedia.org/wiki/Floppy_disk#Sizes,_performance_and_capacity https://en.wikipedia.org/wiki/Floppy_disk#Sizes,_performance... [1] https://www.theregister.com/2000/10/23/32mb_on_a_humble_floppy/ https://www.theregister.com/2000/10/23/32mb_on_a_humble_flop...

gattilorenz 5y ago
> So floppies are RLL too. Yes, in the strict sense of the word. But I think that back in the day MFM indicated a specific (and simple) subset of RLL, while RLL disks were using more efficient encoding. The SuperDisk came out in 96, but the technology for RLL was around in the early 90s (since it was popular for hard drives), and could have used the same media as regular disks, essentially giving you more space "for free" (kinda like formatting disks as DMF, but better), at a time where the floppy was THE media
rasz 5y ago
>SuperDisk achieved by writing more tracks because they replaced stepper motor with voice coils and dynamic head tracking, tracks are no longer fixed in place, plus its write all at once then read only. For practical limits of the unmodified floppy drives you could look at computer build by Chuck Peddle. Peddle was the head designer of 6502, later worked for Tandon on disk drive controllers. Victor 9000 by Sirius https://en.wikipedia.org/wiki/Sirius_Systems_Technology https://en.wikipedia.org/wiki/Sirius_Systems_Technology ~1.2MB on 720 drive. GCR and 9 density zones.

gattilorenz 5y ago

> So floppies are RLL too. Yes, in the strict sense of the word. But I think that back in the day MFM indicated a specific (and simple) subset of RLL, while RLL disks were using more efficient encoding. The SuperDisk came out in 96, but the technology for RLL was around in the early 90s (since it was popular for hard drives), and could have used the same media as regular disks, essentially giving you more space "for free" (kinda like formatting disks as DMF, but better), at a time where the floppy was THE media

rasz 5y ago

>SuperDisk achieved by writing more tracks because they replaced stepper motor with voice coils and dynamic head tracking, tracks are no longer fixed in place, plus its write all at once then read only. For practical limits of the unmodified floppy drives you could look at computer build by Chuck Peddle. Peddle was the head designer of 6502, later worked for Tandon on disk drive controllers. Victor 9000 by Sirius https://en.wikipedia.org/wiki/Sirius_Systems_Technology https://en.wikipedia.org/wiki/Sirius_Systems_Technology ~1.2MB on 720 drive. GCR and 9 density zones.