Hard Disk CMOS Standard Types Geometry

The following table may help when you know the size of a HD of an obsolete PC, but its CMOS doesn't support user-defined types

Some types aren't listed in the next table. They are the supposed user-defined types.

Usually - in newest mainboards -, when you need a user-defined type, you use types 47 and -if I recall correctly- 48. It depends of the BIOS frontend to the CMOS settings

Type Heads Secs/Cyl Cylinders Pre-comp L-zone Capacity (Mb)
1 4 17 306 128 305 10
2 4 17 615 300 615 21
3 6 17 615 300 615 32
4 8 17 940 512 940 65
5 6 17 940 512 940 65
6 4 17 615 no 615 21
7 8 17 462 256 511 32
8 5 17 733 no 733 31
9 15 17 900 no 901 117
10 3 17 820 no 820 21
11 5 17 855 no 855 37
12 7 17 855 no 855 52
13 8 17 306 128 319 21
14 7 17 733 no 733 44
16 4 17 612 all 663 21
17 5 17 977 300 977 42
18 7 17 977 no 977 59
19 7 17 1024 512 1023 62
20 5 17 733 300 732 31
21 7 17 733 300 732 44
22 5 17 733 300 733 31
23 4 17 306 all 336 10
24 5 17 977 no 976 42
26 7 17 1024 no 1023 62
27 11 17 1024 no 1023 98
28 15 17 1024 no 1023 133
29 8 17 1024 no 1023 71
30 11 17 1024 no 1023 98
32 9 17 925 no 926 72
33 10 17 1024 no 1023 89
34 12 17 1024 no 1023 106
35 13 17 1024 no 1023 115
36 14 17 1024 no 1023 124
37 2 17 1024 no 1023 17
38 16 17 1024 no 1023 142
40 6 17 820 no 820 42
41 5 17 1024 1024 1023 44
42 8 17 615 512 615 42
43 7 17 1186 no 1186 72

Started 03/08/2001 / Updated Sun Aug 5 21:32:21 2001

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Viric's Web Site / Webmaster: viric / Started 03/08/2001 / Updated Fri Aug 24 19:51:49 CEST 2001