?????????????写OS????????OS ?泻???????????????????????????????????????????写??????? OS???????? GNU GRUB ?? LILO??????????????????????????? PC ?????????????械????????????????????????????????????????????MS-DOS?????????? MS-DOS ??????????????????????? ????IO.SYS????????3???????????????????????
????BIOS ??????? IBM PC compatible??IBM PC???????  ???????512????????????????0x07C00??位??????????????????? ???????????2????????????0xAA55?? ?????????“???????”?? ????????????????????????????510????????
????MS-DOS????????????FAT???????? ?????????????????????8???? OEM??????????51???????????y??????BIOS????????????? ???3??????????????????睢�?????????婕�???????? ??????????????448???????????写???????????DOS???????????????????????锟�??????????????????????????????????????????????????械????????C????????些??

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???MS-DOS ?????????械???????????????1??? ??椋�

????BIOS???????????????????????????????????????????锟�?
LengthName
2Bytes per sector
1Sectors per cluster
2Number of reserved sectors
1Number of file allocation tables
2Number of root entries
2Number of sectors (if < 65 536)
1Media descriptor
2Sectors per file allocation table
2Sectors per track
2Number of heads
4Number of hidden sectors
4Number of sectors (if ≥ 65 536)
1Disk drive index
1Reserved
1Volume signature
4Volume ID
11Volume label
8Volume type
????????????????????????CPU?????????????味?????????????16位????????????1MiB??????围?? ?640 KiB ???????????????????渭?384KiB???????????????????????????????????????????????????????
???????????????????????????1024???????????卸???????? ????256??????????BIOS????? ?????????????????????512B?? [0x07C00?? 0x07E00)??????????????????[0×00500?? 0x07C00) ??29.75KiB ???? [0x07E00?? 0×80000) ??480.5KiB?? ?????????????? 510.25KiB????[0×80000?? 0xA0000)?谢???128KiB???校? ?????些???????????????BIOS??????????谩?
?????????????????????????校??????[0x07E00?? 0x07E05) 5B?????????械????????????????IO.SYS??????????? ????? [0×00500?? 0x07C00) 29.75B?????????????? ????????????????32B?? ????味?? IO.SYS ??????????952????????械????????MS-DOS 4.0 ???IO.SYS?root???械??????????. ?卤????????????????
Length  Name
8   Filename
3   Extension
1   Attributes
1   Reserved
1   Creation time?? microseconds part
2   Creation time
2   Creation date
2   Last access date
2   Reserved
2   Last modified time
2   Last modified date
2   Cluster offset
4   File size in bytes
??????????16位??小???little-endian??????YYYYYYYMMMMDDDDD???????娲�?? ??????16位??小???little-endian??????????HHHHHMMMMMMSSSSS???????娲�??
???????IO.SYS?? ????3???????????? 0×00700??????????? ???????3?????????????????????????[0×00500?? 0×00700)  ???????512???????????????IO.SYS??????????????????????
????????????????????????????16-bit opcodes???????????????????? ?????????????????GCC ??binutils????????小????????????????. ?????????C?????屑???.code16gcc???????????? ???????????????????????????? ?????????????????????????????????危???????????危??????????????????????????????????????????
?????????????????????锌???????????
????LICENSE
????boot.c
????boot.ld
????Makefile
????????????? Google Code????? MIT 协?椤�