fasm完成一個簡單的FAT12的鏡像檔案

 fasm完成一個簡單的FAT12的鏡像檔案，方便裸機編程，以自己動手寫作業系統的FAT12布局為例。

;-----------------------------------------------------------------------;--===-- FAT12 image file make By G-Spider;--===-- fasm  startOS.asm startOS.img;-----------------------------------------------------------------------; here is map of how the FAT12 system is laid out ;|----------------------------------------------------------------------| ;|BootSector| FAT table 1| FAT table 2 | Root Directory| Data Region    | ;|512 bytes | 4,608 bytes| 4,608 bytes |  7,168 bytes  | 1,457,664 bytes| ;|1 sector  | 9 sectors  | 9 sectors   |  14 sectors   |  2,847 sectors | ;|______________________________________________________________________| ;-----------------------------------------------------------------------;BootSector;-----------------------------------------------------------------------file 'myboot.bin'               ;0號扇區 512Byte;-----------------------------------------------------------------------;FAT table 1;-----------------------------------------------------------------------FATEntry:db 00h,00h,00h,0ffh,0fh         ;有效位 奇:0ffh,0fh 偶:0f0h,0ffhFATEntrySize = $-FATEntrydb 9*512-FATEntrySize dup(0)    ;FAT1 01~09號扇區;-----------------------------------------------------------------------;FAT table 2;-----------------------------------------------------------------------db 00h,00h,00h,0ffh,0fhdb 9*512-FATEntrySize dup(0)    ;FAT2 10~18號扇區;-----------------------------------------------------------------------;Root Directory;-----------------------------------------------------------------------RootDir:                        ;19號扇區    .Name       db "LOADER  BIN"    .Attr       db 20h    .Reserved   db 0,0,0,0,0,0,0,0,0,0    .WrtTime    dw 7a5bh    .WrtDate    dw 3185h    .FstClus    dw 0002h        ;開始簇號2 (對應FAT table 1的第3位元組處)    .FileSize   dd 0000000fh    ;loader.bin檔案大小RootDirSize     =$-RootDir      ;32 Bytedb 14*512-RootDirSize  dup(0);-----------------------------------------------------------------------;Data Region;-----------------------------------------------------------------------LOADER:file 'loader.bin'               ;34號扇區LOADERSIZE = $-LOADERdb (2880-1-9-9-14)*512 -LOADERSIZE dup (0);-----------------------------------------------------------------------

效果(日期隨便設定一下)：

vmware載入效果：

升級一下：

;-----------------------------------------------------------------------;--===-- FAT12 image file make By G-Spider;--===-- fasm  startOS.asm startOS.img;-----------------------------------------------------------------------; here is map of how the FAT12 system is laid out ;|----------------------------------------------------------------------| ;|BootSector| FAT table 1| FAT table 2 | Root Directory| Data Region    | ;|512 bytes | 4,608 bytes| 4,608 bytes |  7,168 bytes  | 1,457,664 bytes| ;|1 sector  | 9 sectors  | 9 sectors   |  14 sectors   |  2,847 sectors | ;|______________________________________________________________________| struc _DATA def{    match d1=,d2=,d3, def     \{     .Data dw ((d1-1980) shl 9) or ((d2 and 0fh) shl 5)  or (d3 and 1fh)     \} }struc _TIME def{    match d1:d2:d3, def    \{     .Data dw (d1 shl 11) or ((d2 and 3fh) shl 5)  or ((d3 and 0fh) shr 1)    \} };-----------------------------------------------------------------------;BootSector;-----------------------------------------------------------------------file 'boot.bin'                 ;0號扇區 512Byte;-----------------------------------------------------------------------;FAT table 1;-----------------------------------------------------------------------FATEntry:db 00h,00h,00h,0ffh,0fh         ;有效位 奇:0ffh,0fh 偶:0f0h,0ffhFATEntrySize = $-FATEntrydb 9*512-FATEntrySize dup(0)    ;FAT1 01~09號扇區;-----------------------------------------------------------------------;FAT table 2;-----------------------------------------------------------------------db 00h,00h,00h,0ffh,0fhdb 9*512-FATEntrySize dup(0)    ;FAT2 10~18號扇區;-----------------------------------------------------------------------;Root Directory;-----------------------------------------------------------------------RootDir:                        ;19號扇區    .Name       db "EXAMPLE COM"    .Attr       db 20h    .Reserved   db 0,0,0,0,0,0,0,0,0,0    .WrtTime    _TIME <15:56:12>    .WrtDate    _DATA <2011,10,26>    .FstClus    dw 0002h        ;開始簇號2 (對應FAT table 1的第3位元組處)    .FileSize   dd LOADERSIZE   ;loader.bin檔案大小RootDirSize     =$-RootDir      ;32 Bytedb 14*512-RootDirSize  dup(0);-----------------------------------------------------------------------;Data Region;-----------------------------------------------------------------------LOADER:file 'loader.bin'               ;33號扇區LOADERSIZE = $-LOADERdb (2880-1-9-9-14)*512 -LOADERSIZE dup (0);-----------------------------------------------------------------------

再升級一下：

;-----------------------------------------------------------------------;--===-- FAT12 image file make By G-Spider;--===-- fasm  startOS.asm startOS.img;-----------------------------------------------------------------------; here is map of how the FAT12 system is laid out ;|----------------------------------------------------------------------| ;|BootSector| FAT table 1| FAT table 2 | Root Directory| Data Region    | ;|512 bytes | 4,608 bytes| 4,608 bytes |  7,168 bytes  | 1,457,664 bytes| ;|1 sector  | 9 sectors  | 9 sectors   |  14 sectors   |  2,847 sectors | ;|______________________________________________________________________| struc _DATA def{    match d1=,d2=,d3, def     \{     .Data dw ((d1-1980) shl 9) or ((d2 and 0fh) shl 5)  or (d3 and 1fh)     \} }struc _TIME def{    match d1:d2:d3, def    \{     .Data dw (d1 shl 11) or ((d2 and 3fh) shl 5)  or ((d3 and 0fh) shr 1)    \} };-----------------------------------------------------------------------;BootSector;-----------------------------------------------------------------------file 'BOOTER.SYS'               ;0號扇區 512Byte;-----------------------------------------------------------------------;FAT table 1;-----------------------------------------------------------------------FATEntry1:;db 00h,00h,00h,0ffh,0fh        ;有效位 奇:0ffh,0fh 偶:0f0h,0ffh;佔用5個扇區2,3,4,5,6;佔用扇區7db 00h,00h,00h,03h,40h,00h,05h,60h,00h,0ffh,0ffh,0ffhFATEntrySize = $-FATEntry1db 9*512-FATEntrySize dup(0)    ;FAT1 01~09號扇區;-----------------------------------------------------------------------;FAT table 2;-----------------------------------------------------------------------FATEntry2: rb FATEntrySize repeat FATEntrySize  load a byte from FATEntry1+%-1  store byte a at FATEntry2+%-1end repeatdb 9*512-FATEntrySize dup(0)    ;FAT1 10~18號扇區;-----------------------------------------------------------------------;Root Directory 根目錄;-----------------------------------------------------------------------RootDir1:                       ;19號扇區    .Name       db "SYSTEM  SYS"    .Attr       db 20h    .Reserved   db 0,0,0,0,0,0,0,0,0,0    .WrtTime    _TIME <21:06:12>    .WrtDate    _DATA <2011,10,27>    .FstClus    dw 0002h        ;開始簇號2 (對應FAT table 1的第3位元組處)    .FileSize   dd LOADERSIZE1RootDir2:                       ;19號扇區    .Name       db "EXAMPLE1X3D"    .Attr       db 20h    .Reserved   db 0,0,0,0,0,0,0,0,0,0    .WrtTime    _TIME <21:06:12>    .WrtDate    _DATA <2011,10,27>    .FstClus    dw 0007h        ;開始簇號7    .FileSize   dd LOADERSIZE2   db 14*512-($-RootDir1)  dup(0);-----------------------------------------------------------------------;Data Region;-----------------------------------------------------------------------LOADER1:file 'SYSTEM.SYS'               ;33號扇區 ;2347位元組 佔用5個扇區2,3,4,5,6LOADERSIZE1 = $-LOADER1LOADER2:file 'EXAMPLE1.X3D'             ; *號扇區 ;69位元組 扇區7LOADERSIZE2 = $-LOADER2db (2880-1-18-14)*512 -($-LOADER1) dup (0);-----------------------------------------------------------------------