| 1 | A | B | C | D | E | F | G | H | I | J | K | L |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 2 | Disk density - Overview |  |  |  |  |  |  |  |  |  |  |  |
| 3 | Size | 8-inch | 8-inch | 5¼-inch | 5¼-inch | 5¼-inch | 5¼-inch | 3½-inch | 3½-inch | 3½-inch | 3½-inch | 3½-inch |
| 4 | Density | SD | DD | SD | DD | QD | HD | DD | DD | HD | ED | TD |
| 5 | Disk coating | Iron oxide | Iron oxide | Iron oxide | Iron oxide | Iron oxide | Cobalt | ? | Iron oxide, Cobalt? | Cobalt | Barium ferrite | ? |
| 6 | 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 | ? |
| 7 | 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 | ? | ? |
| 8 | Line code | FM | MFM, M²FM, FM/MFM or GCR | FM | MFM or GCR | MFM or GCR | MFM | MFM | MFM or GCR | MFM | MFM | MFM |
| 9 | 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 | ? |
| 10 | Track density [tpi] | 48 | 48 | 48 | 48 | 96 or 100 | 96 | 67.5 | 135 | 135 | 135 | 406.5 |
| 11 | Bit density [bpi] | 5876, 5922 | 5876, 5922 | 5876, 5922 | 5876, 5922 | 5876, 5922 | 9646, 9870 | 8650 | 8717 | 17432, 17434 | 34868 | 36700 |
| 12 | 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.