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and Components Reference Guide | Floppy Disk Drives | Floppy Disk Formats and Logical Structures ]
Summary of Floppy Disk Types and Specifications
The following table shows a summary of the various floppy disk specifications provided
in other sections of this chapter, for each of the five major floppy disk types:
Category |
Specification |
360 KB 5.25" |
1.2 MB 5.25" |
720 KB 3.5" |
1.44 MB 3.5" |
2.88 MB 3.5" |
Drive |
Read/Write Heads
(Data Surfaces) |
2 |
2 |
2 |
2 |
2 |
Spindle Motor Speed |
300 RPM |
360 RPM |
300 RPM |
300 RPM |
300 RPM |
Controller |
Minimum Controller
Transfer Rate |
250 Kbits/s |
500 Kbits/s |
250 Kbits/s |
500 Kbits/s |
1 Mbits/s |
Media |
Track Density (TPI) |
48 |
96 |
135 |
135 |
135 |
Bit Density (BPI) |
5,876 |
9,869 |
8,717 |
17,434 |
34,868 |
Density Name |
Double Density (DD) |
High Density (HD) |
Double Density (DD) |
High Density (HD) |
Extra-High Density (ED) |
Geometry |
Tracks (Cylinders) |
40 |
80 |
80 |
80 |
80 |
Sectors Per
Track/Cylinder |
9 |
15 |
9 |
18 |
36 |
Total Sectors Per
Disk |
720 |
2,400 |
1,440 |
2,880 |
5,760 |
File
System |
Cluster Size |
2 sectors |
1 sector |
2 sectors |
1 sector |
2 sectors |
Maximum Root
Directory Entries |
112 |
224 |
112 |
224 |
448 |
Capacity |
Unformatted Capacity |
~480 KB |
~ 1.6 MB |
~1 MB |
~2 MB |
~4 MB |
Formatted Capacity
(binary kilobytes) |
360 |
1,200 |
720 |
1,440 |
2,880 |
Formatted Capacity
(bytes) |
368,640 |
1,228,800 |
737,280 |
1,474,560 |
2,949,120 |
File System Overhead
(bytes) |
6,144 |
14,848 |
7,168 |
16,896 |
17,408 |
Total Usable
Capacity (bytes) |
362,496 |
1,213,952 |
730,112 |
1,457,664 |
2,931,712 |
Total Usable
Capacity (binary KB) |
354 |
1,185.5 |
713 |
1,423.5 |
2,863 |
Total Usable
Capacity (binary MB) |
0.346 |
1.158 |
0.696 |
1.390 |
2.796 |
Next: Floppy Disk
Interfacing and Configuration
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