4 ms·

Stupid question: if I got my history right, in the late 80s/early 90s HDs there was the big move from MFM to RLL hard drives. Why didn't floppy disks start usin

Stupid question: if I got my history right, in the late 80s/early 90s HDs there was the big move from MFM to RLL hard drives. Why didn't floppy disks start using RLL back in the day too? Was it just for compatibility? 3.5" disks weren't compatible with 5.25" ones either, but that didn't stop them from dominating the market.

kevin_thibedeau 5y ago
Floptical was RLL. LS120 may have been as well. The killer is that BIOS support was never universal beyond HD floppy media. Another upgrade was never going to work as evidenced by ED 2.88MB failure to gain traction.
- gattilorenz 5y ago
  > Another upgrade was never going to work as evidenced by ED 2.88MB failure to gain traction But wasn't the 2.88MB format using entirely different (and less economical/available) media as well? As far as I understand, RLL could have used the same media. BIOS support, on the other hand, could have been a limiting factor, as you point out.
  - kevin_thibedeau 5y ago
    It would require smarter on-board drive electronics. Commodity floppies were kept as dumb devices to minimize costs. SCSI was cost prohibitive and ATAPI came along too late. The only other option would be a hack on the existing floppy interface.
justsomehnguy 5y ago
> 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.

kevin_thibedeau 5y ago

Floptical was RLL. LS120 may have been as well. The killer is that BIOS support was never universal beyond HD floppy media. Another upgrade was never going to work as evidenced by ED 2.88MB failure to gain traction.

gattilorenz 5y ago
> Another upgrade was never going to work as evidenced by ED 2.88MB failure to gain traction But wasn't the 2.88MB format using entirely different (and less economical/available) media as well? As far as I understand, RLL could have used the same media. BIOS support, on the other hand, could have been a limiting factor, as you point out.
- kevin_thibedeau 5y ago
  It would require smarter on-board drive electronics. Commodity floppies were kept as dumb devices to minimize costs. SCSI was cost prohibitive and ATAPI came along too late. The only other option would be a hack on the existing floppy interface.

justsomehnguy 5y ago

> 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.