Did 5.25" floppies undergo a change in magnetic coating?
3.5" floppy disks, in the transition from 720K to 1.44M, changed the actual coating to a different compound that was magnetically 'stiffer'. This was necessary to support the higher density, but meant the old disks could not support the new high-density format even if used in a new drive. A more subtle and much nastier problem: if you formatted a new disk in an old drive, everything would seem fine, but the information would not have been recorded strongly enough, and might fade over the next few days.
5.25" floppies made several format transitions that together accomplished an order of magnitude capacity increase until the final 1.2M format. Did any of these transitions involve a similar change in the actual coating? Or did the disks themselves stay interchangeable apart from issues of hard versus soft sectors?
history hardware floppy-disk
asked 12 hours ago
rwallacerwallace
9,405446138
add a comment |
3.5" floppy disks, in the transition from 720K to 1.44M, changed the actual coating to a different compound that was magnetically 'stiffer'. This was necessary to support the higher density, but meant the old disks could not support the new high-density format even if used in a new drive. A more subtle and much nastier problem: if you formatted a new disk in an old drive, everything would seem fine, but the information would not have been recorded strongly enough, and might fade over the next few days.
5.25" floppies made several format transitions that together accomplished an order of magnitude capacity increase until the final 1.2M format. Did any of these transitions involve a similar change in the actual coating? Or did the disks themselves stay interchangeable apart from issues of hard versus soft sectors?
history hardware floppy-disk
asked 12 hours ago
rwallacerwallace
9,405446138
add a comment |
3.5" floppy disks, in the transition from 720K to 1.44M, changed the actual coating to a different compound that was magnetically 'stiffer'. This was necessary to support the higher density, but meant the old disks could not support the new high-density format even if used in a new drive. A more subtle and much nastier problem: if you formatted a new disk in an old drive, everything would seem fine, but the information would not have been recorded strongly enough, and might fade over the next few days.
5.25" floppies made several format transitions that together accomplished an order of magnitude capacity increase until the final 1.2M format. Did any of these transitions involve a similar change in the actual coating? Or did the disks themselves stay interchangeable apart from issues of hard versus soft sectors?
history hardware floppy-disk
asked 12 hours ago
rwallacerwallace
9,405446138
3.5" floppy disks, in the transition from 720K to 1.44M, changed the actual coating to a different compound that was magnetically 'stiffer'. This was necessary to support the higher density, but meant the old disks could not support the new high-density format even if used in a new drive. A more subtle and much nastier problem: if you formatted a new disk in an old drive, everything would seem fine, but the information would not have been recorded strongly enough, and might fade over the next few days.
5.25" floppies made several format transitions that together accomplished an order of magnitude capacity increase until the final 1.2M format. Did any of these transitions involve a similar change in the actual coating? Or did the disks themselves stay interchangeable apart from issues of hard versus soft sectors?
history hardware floppy-disk
history hardware floppy-disk
asked 12 hours ago
rwallacerwallace
9,405446138
asked 12 hours ago
rwallacerwallace
9,405446138
asked 12 hours ago
rwallacerwallace
9,405446138
asked 12 hours ago
rwallacerwallace
9,405446138
asked 12 hours ago
rwallacerwallace
9,405446138
9,405446138
add a comment |
add a comment |
1 Answer
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The main technical parameter for a floppy disk's coating is its coercitiviy, i.e. the resistance of ferromagnetic matter to withstand demagnetization. Coercitivity is measured in Oersted, after Hans Christian Ørsted, a Danish physicist who discovered the magnetic impact of electrical current.
- 5 1/4" disks storing 360K and 720K (SD and DD) used a coating with a coercitivity of 300 Oersted.
- 5 1/4 disks storing 1.2M used a coating with a coercitivity of 600 Oersted.
So yes, the coating was changed to support the HD format.
The difference between 5 1/4" DD and HD coating is much larger than the same difference between 3 1/2" DD and HD media - which is 660 Oe an 720 Oe, respectively.
answered 10 hours ago
tofrotofro
15.7k33190
Do you have any idea why the difference in 3.5" was smaller? Is it because DD had already a higher than needed coercivity (by the way, you have a typo there) from the beginning? Does that also mean that they could have produced DD-compatible drives with higher capacity instead of introducing a slightly different coating?
– Selcuk
4 hours ago
add a comment |
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1 Answer
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1 Answer
1
active
oldest
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active
oldest
votes
The main technical parameter for a floppy disk's coating is its coercitiviy, i.e. the resistance of ferromagnetic matter to withstand demagnetization. Coercitivity is measured in Oersted, after Hans Christian Ørsted, a Danish physicist who discovered the magnetic impact of electrical current.
- 5 1/4" disks storing 360K and 720K (SD and DD) used a coating with a coercitivity of 300 Oersted.
- 5 1/4 disks storing 1.2M used a coating with a coercitivity of 600 Oersted.
So yes, the coating was changed to support the HD format.
The difference between 5 1/4" DD and HD coating is much larger than the same difference between 3 1/2" DD and HD media - which is 660 Oe an 720 Oe, respectively.
answered 10 hours ago
tofrotofro
15.7k33190
Do you have any idea why the difference in 3.5" was smaller? Is it because DD had already a higher than needed coercivity (by the way, you have a typo there) from the beginning? Does that also mean that they could have produced DD-compatible drives with higher capacity instead of introducing a slightly different coating?
– Selcuk
4 hours ago
add a comment |
The main technical parameter for a floppy disk's coating is its coercitiviy, i.e. the resistance of ferromagnetic matter to withstand demagnetization. Coercitivity is measured in Oersted, after Hans Christian Ørsted, a Danish physicist who discovered the magnetic impact of electrical current.
- 5 1/4" disks storing 360K and 720K (SD and DD) used a coating with a coercitivity of 300 Oersted.
- 5 1/4 disks storing 1.2M used a coating with a coercitivity of 600 Oersted.
So yes, the coating was changed to support the HD format.
The difference between 5 1/4" DD and HD coating is much larger than the same difference between 3 1/2" DD and HD media - which is 660 Oe an 720 Oe, respectively.
answered 10 hours ago
tofrotofro
15.7k33190
Do you have any idea why the difference in 3.5" was smaller? Is it because DD had already a higher than needed coercivity (by the way, you have a typo there) from the beginning? Does that also mean that they could have produced DD-compatible drives with higher capacity instead of introducing a slightly different coating?
– Selcuk
4 hours ago
add a comment |
The main technical parameter for a floppy disk's coating is its coercitiviy, i.e. the resistance of ferromagnetic matter to withstand demagnetization. Coercitivity is measured in Oersted, after Hans Christian Ørsted, a Danish physicist who discovered the magnetic impact of electrical current.
- 5 1/4" disks storing 360K and 720K (SD and DD) used a coating with a coercitivity of 300 Oersted.
- 5 1/4 disks storing 1.2M used a coating with a coercitivity of 600 Oersted.
So yes, the coating was changed to support the HD format.
The difference between 5 1/4" DD and HD coating is much larger than the same difference between 3 1/2" DD and HD media - which is 660 Oe an 720 Oe, respectively.
answered 10 hours ago
tofrotofro
15.7k33190
The main technical parameter for a floppy disk's coating is its coercitiviy, i.e. the resistance of ferromagnetic matter to withstand demagnetization. Coercitivity is measured in Oersted, after Hans Christian Ørsted, a Danish physicist who discovered the magnetic impact of electrical current.
- 5 1/4" disks storing 360K and 720K (SD and DD) used a coating with a coercitivity of 300 Oersted.
- 5 1/4 disks storing 1.2M used a coating with a coercitivity of 600 Oersted.
So yes, the coating was changed to support the HD format.
The difference between 5 1/4" DD and HD coating is much larger than the same difference between 3 1/2" DD and HD media - which is 660 Oe an 720 Oe, respectively.
answered 10 hours ago
tofrotofro
15.7k33190
edited 9 hours ago
answered 10 hours ago
tofrotofro
15.7k33190
answered 10 hours ago
tofrotofro
15.7k33190
answered 10 hours ago
tofrotofro
15.7k33190
15.7k33190
Do you have any idea why the difference in 3.5" was smaller? Is it because DD had already a higher than needed coercivity (by the way, you have a typo there) from the beginning? Does that also mean that they could have produced DD-compatible drives with higher capacity instead of introducing a slightly different coating?
– Selcuk
4 hours ago
add a comment |
Do you have any idea why the difference in 3.5" was smaller? Is it because DD had already a higher than needed coercivity (by the way, you have a typo there) from the beginning? Does that also mean that they could have produced DD-compatible drives with higher capacity instead of introducing a slightly different coating?
– Selcuk
4 hours ago
Do you have any idea why the difference in 3.5" was smaller? Is it because DD had already a higher than needed coercivity (by the way, you have a typo there) from the beginning? Does that also mean that they could have produced DD-compatible drives with higher capacity instead of introducing a slightly different coating?
– Selcuk
4 hours ago
Do you have any idea why the difference in 3.5" was smaller? Is it because DD had already a higher than needed coercivity (by the way, you have a typo there) from the beginning? Does that also mean that they could have produced DD-compatible drives with higher capacity instead of introducing a slightly different coating?
– Selcuk
4 hours ago
add a comment |
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