Disk density
Overview

Size
8-inch
8-inch
5¼-inch
5¼-inch
5¼-inch
5¼-inch
3½-inch
3½-inch
3½-inch
3½-inch
3½-inch
Density
SD
DD
SD
DD
QD
HD
DD
DD
HD
ED
TD
Disk coating
Iron oxide
Iron oxide
Iron oxide
Iron oxide
Iron oxide
Cobalt
?
Iron oxide, Cobalt?
Cobalt
Barium ferrite
?
Coercivity [Oe]
290, 300
290, 300
290, 300
290, 300
290, 300
600, 660, 670
ca. 600
600?, 660, 670
700, 720
750?, 1060, 1200
?
Coating thickness [µ-inch]
?
?
?
100, 2.5 µm, 2.0-3.0 µm
?
55, 1.3 µm, 1.0-1.5 µm
?
65, 1.9 µm, 2.0-3.0 µm
55, 0.9 µm, 1.0-1.5 µm
?
?
Line code
FM
MFM, M²FM, FM/MFM or GCR
FM
MFM or GCR
MFM or GCR
MFM
MFM
MFM or GCR
MFM
MFM
MFM
Track width
0.330 mm
0.330 mm
0.330 mm
0.330 mm
0.160 mm
0.160 mm
?
0.115 mm
0.115 mm
0.115 mm
?
Track density [tpi]
48
48
48
48
96 or 100
96
67.5
135
135
135
406.5
Bit density [bpi]
5876, 5922
5876, 5922
5876, 5922
5876, 5922
5876, 5922
9646, 9870
8650
8717
17432, 17434
34868
36700
Recording direction
longitudinal / horizontal
longitudinal / horizontal
longitudinal / horizontal
longitudinal / horizontal
longitudinal / horizontal
longitudinal / horizontal
longitudinal / horizontal
longitudinal / horizontal
longitudinal / horizontal
perpendicular / vertical
-

Question: What's the tpi and bpi of HD?
Answer: High density (HD) utilizes a 96 tpi track density allowing 9646 bpi.