how to expand dosubcd.img and make it still bootable?

[hoohooslax]

In the fd011520.img file, sectors per cluster is 8, not 240...so how do you get 240?

[as702]

In the fd011520.img file, sectors per cluster is 8, not 240...so how do you get 240?

christ, how did i do this math (i'm an engineer too). :p

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capacity(bytes) = cylinders * number of heads per cylinder * number of sectors per head * 512(bytes per sector)

ok, "c" should NOT be 240. if we do the math based on the above equation.

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capacity(KB) = 11,520 KB
capacity(in bytes) = 11,520*1024 = 11,796,480

therefore, to find the number of cylinders:

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c = capacity(bytes) / number of heads / number of sectors / bytes per sector
  = 11,796,480 / 8 / 36 / 512 (bytes per sector)
  = 80

c=80 h=8 s=36

heh. it should be 80 cylinders for the 11,520Kb image, NOT 240 (???). if we apply the same math to 5,760Kb, the number of cylinders work out at 80 again.

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80(c) * 4(h) * 36(s) * 512(bytes per sector) = 5,898,240 bytes (or 5760Kb)

c=80 h=4 s=36




and, for the 50mb image (or 56,195Kb in this case), based on the stats provided by winimage, we should have

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57,543,680 (capacity in bytes) / 63 (sectors per track) / 255 (heads) / 512 (bytes per sector) = approx 7.

c=7 h=255 s=63


so, put simply - ignore those figures i quoted earlier and use the above equation to help you determine how many cylinders you need (since winimage doesn't appear to supply you with one).

sorry for the blunder.