Quote:
Originally Posted by mole42uk
I'm attaching the specification page from the user manual, seems to differ from my memory of the accepted capacity of floppies! I should think that techniques developed to get more data per disk than when the drives were originally made.
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Well their figures more or less add up, as they've specified that formatted capacity is using 16 (256-Byte) sectors per track = 4096 Bytes per track. So:
1 sides * 40 Tracks * 4096 = 163840 Bytes (160KiB) Spec: says 164KB
2 sides * 40 Tracks * 4096 = 327680 Bytes (320KiB) Spec: says 328KB
1 sides * 40 Tracks * 4096 = 327680 Bytes (320KiB) Spec: says 328KB
2 sides * 80 Tracks * 4096 = 655360 Bytes (640KiB) Spec: says 656KB
(So looks like they been using HDD definition of 1000 Bytes (1kB), rather than original 1024 Bytes (1KB, now 1KiB to save confusion) used for memory - as well as rounding-up)
Capacity using Double-density (MFM) on PC's 9 (512-Byte) sectors per track = 4608 Bytes per track. So:
2 sides * 40 Tracks * 4608 = 368640 Bytes (360KiB) (Original main 5.25" format)
2 sides * 80 Tracks * 4608 = 737280 Bytes (720KiB) (Original main 3.5" format)
PC Hi / Quad Density formats use higher (but different) number of 512Bytes sectors per track (15 for 1.2MB & 18 for 1.44MB)