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The floppy drive has a stepper motor that controls the placement of the read/write head above the disk. In the ST era, the control of that motor was directly u

The floppy drive has a stepper motor that controls the placement of the read/write head above the disk. In the ST era, the control of that motor was directly under the control of the operating system. For an 80 track disk, the movement required to step between tracks was a certain known amount. If you formatted the disk with the tracks spaced closer together, by altering the stepper movement during that process, you would 'magically' get more space.

prox 6y ago
Weren’t there special compression softwares that added even more capacity?
- NovemberWhiskey 6y ago
  I don't really remember any: my main recollection as an ST user was the format programs that let you increase the track count and the sector density. I recall the default format was 9 sectors, 80 tracks, 2 sides with 512 bytes per sector = 720KB, and you could push up to sometimes 82/83 tracks and maybe 10 or 11 sectors to get more out of a diskette. Actually, I think my ST originally came with a single-sided floppy drive and had to be upgraded.
  - Zenst 6y ago
    The initial release of Atari's has single sided drives, I think the 1040ST had Double sided though, they did upgrade that shortly afterwards I believe to enable the marketing bods to show a larger number they could compare to the Amiga. So was only early 512STFM systems and those had a red drive light and the double sided had a green one if my memory holds. Sad thing was, due to the early single sided models, many games would limit to 720k so as to not limit there market. That saw games that would happily fit upon a single double sided disc, cast upon two floppies forcing switching. So that small batch of single sided initial release systems, really did have a legacy impact that lasted for years and did it no favours.
- Zenst 6y ago
  There was, can't recall the one that was popular prior to Microsoft adding https://en.wikipedia.org/wiki/DriveSpace https://en.wikipedia.org/wiki/DriveSpace MSDOS 6.0
  - FilthyAnalyst 6y ago
    Stacker was pretty common in the early 90s.
  - simcop2387 6y ago
    That'd probably be DoubleDisk or Stacker. https://forum.winworldpc.com/discussion/10401/software-spotlight-drive-compression-tools https://forum.winworldpc.com/discussion/10401/software-spotl...
rasz 6y ago
>In the ST era, the control of that motor was directly under the control of the operating system. No, it was under control of a stepper motor driver circuit located directly on a Floppy drive pcb. This driver in turn received instructions from a dedicated Floppy drive controller (WD1771 and compatibles). > For an 80 track disk, the movement required to step between tracks was a certain known amount. "certain known amount" being one step per track >If you formatted the disk with the tracks spaced closer together, by altering the stepper movement during that process, you would 'magically' get more space. Above is incorrect. Its impossible to move HEAD stepper motor between tracks. Floppy drive has a STEP (/STEP) and DIRECTION (/DIR) pins. All you are able to do is pick direction and step one track at a time. Step distance is Fixed. The whole point of using a stepper motor is you dont have to worry about head tracking/alignment. The only personal computer Floppy drives with flexible head positioning all used voice coil head actuator - Floptical, LS-120/240, Zip drives etc. https://twtext.com/article/1263702402886057984 https://twtext.com/article/1263702402886057984
kabdib 6y ago
The disk controller chip let you seek track by track. No fine control at all. You could format extra tracks, if you felt lucky. Usually you could get away with couple extra. I never did this with any files I valued.

prox 6y ago

Weren’t there special compression softwares that added even more capacity?

NovemberWhiskey 6y ago
I don't really remember any: my main recollection as an ST user was the format programs that let you increase the track count and the sector density. I recall the default format was 9 sectors, 80 tracks, 2 sides with 512 bytes per sector = 720KB, and you could push up to sometimes 82/83 tracks and maybe 10 or 11 sectors to get more out of a diskette. Actually, I think my ST originally came with a single-sided floppy drive and had to be upgraded.
- Zenst 6y ago
  The initial release of Atari's has single sided drives, I think the 1040ST had Double sided though, they did upgrade that shortly afterwards I believe to enable the marketing bods to show a larger number they could compare to the Amiga. So was only early 512STFM systems and those had a red drive light and the double sided had a green one if my memory holds. Sad thing was, due to the early single sided models, many games would limit to 720k so as to not limit there market. That saw games that would happily fit upon a single double sided disc, cast upon two floppies forcing switching. So that small batch of single sided initial release systems, really did have a legacy impact that lasted for years and did it no favours.
Zenst 6y ago
There was, can't recall the one that was popular prior to Microsoft adding https://en.wikipedia.org/wiki/DriveSpace https://en.wikipedia.org/wiki/DriveSpace MSDOS 6.0
- FilthyAnalyst 6y ago
  Stacker was pretty common in the early 90s.
- simcop2387 6y ago
  That'd probably be DoubleDisk or Stacker. https://forum.winworldpc.com/discussion/10401/software-spotlight-drive-compression-tools https://forum.winworldpc.com/discussion/10401/software-spotl...

rasz 6y ago

>In the ST era, the control of that motor was directly under the control of the operating system. No, it was under control of a stepper motor driver circuit located directly on a Floppy drive pcb. This driver in turn received instructions from a dedicated Floppy drive controller (WD1771 and compatibles). > For an 80 track disk, the movement required to step between tracks was a certain known amount. "certain known amount" being one step per track >If you formatted the disk with the tracks spaced closer together, by altering the stepper movement during that process, you would 'magically' get more space. Above is incorrect. Its impossible to move HEAD stepper motor between tracks. Floppy drive has a STEP (/STEP) and DIRECTION (/DIR) pins. All you are able to do is pick direction and step one track at a time. Step distance is Fixed. The whole point of using a stepper motor is you dont have to worry about head tracking/alignment. The only personal computer Floppy drives with flexible head positioning all used voice coil head actuator - Floptical, LS-120/240, Zip drives etc. https://twtext.com/article/1263702402886057984 https://twtext.com/article/1263702402886057984

kabdib 6y ago

The disk controller chip let you seek track by track. No fine control at all. You could format extra tracks, if you felt lucky. Usually you could get away with couple extra. I never did this with any files I valued.