Changes between Version 1 and Version 2 of Ticket #27, comment 8
- Timestamp:
- Nov 15, 2016, 11:50:50 PM (8 years ago)
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Ticket #27, comment 8
v1 v2 1 1 Forgot to say: not only the MBR and DLAT sector are "faked" in memory but also the VBR (the first real sector on the large floppy, the one containing the real BPB).[[BR]] 2 2 Yes, "hidden sectors" is changed to "skip" all the sectors preceding the first real data sector (the original VBR).[[BR]] 3 Additionally, "NumHeads" and "SectorsPerTrack" are also changed to what OS/2 requires (NumHeads = 255, SectorsPerTrack = 63 ).[[BR]]3 Additionally, "NumHeads" and "SectorsPerTrack" are also changed to what OS/2 requires (NumHeads = 255, SectorsPerTrack = 63/127/255 depending on media size).[[BR]] 4 4 However, I don't think that booting will work from such a media as I suppose the BIOS will access the real VBR (because virtualization is not in effect on bootup). I have no clue what will happen if the values in the real VBR deviate from those emulated later on.[[BR]] 5 5 In short: I have never tried booting from USB media. 6 6 7 Another note: the number of hidden sectors is not necessarily 63. That's because of the necessity to align the "partition" to a cylinder boundary (OS/2 is very picky about that, it was such a pain in the butt). I decided to align the END of the partition to a cylinder boundary which means the START will not align if the partition is not an exact multiple of 255 (NumHeads) *63 (SectorsPerTrack) sectors.7 Another note: the number of hidden sectors is not necessarily 63. That's because of the necessity to align the "partition" to a cylinder boundary (OS/2 is very picky about that, it was such a pain in the butt). I decided to align the END of the partition to a cylinder boundary which means the START will not align if the partition is not an exact multiple of 255 (NumHeads) *63/127/255 (SectorsPerTrack) sectors.
