Flashpath for Linux

Q: How do we know that this is a 4MB module?

Read Control Sector 512 bytes (sector 1, the boot sector)
00h 3 E9 84 01 jump Jump to executable code. Only relevant for boot disks
03h 8 FLASHPTH banner OEM name and version.
0Bh w 2 0200h 512 secsize Bytes per sector
0Dh b 1 FFh 255 clsiz Sectors per cluster (allocation unit size).
0Eh w 2 0001h nrsvsect Number of reserved sectors (starting at 0). Make sence as the two first sectors are special.
10h b 1 02h nfat Number of FAT's on disk.
11h w 2 0010h dirents Number of root directory entries (directory size).
13h w 2 0B40h 2880 psect Number of total sectors (0 if partition > 32Mb).
15h b 1 F9h descr Media descriptor byte. F9h = 3,5 Double Sided, Double High Density diskette (9 sector).
16h w 2 0001h fatlen Sectors per FAT.
18h w 2 0012h 18 nsect Sectors per track(cylinder). This is 1 Status sector, 1 Control sector and 16 data sectors
1Ah w 2 0001h nheads Number of heads.
1Ch w 2 0000h nhs Number of hidden sectors.
1Eh w 2 Not used
20h dw 4 00000000h bigsect Number of sectors if offset 13h was 0.
24h b 1 00h physdrive Physical drive number. ?? must be inserted by software
25h b 1 00h reserved Reserved.
26h b 1 29h dos4 Signature byte (29h).
27h dw 4 FDFDFDFDh serial Volume serial number.
2Bh 11 FlashPath.. label Volume label. (the two dots in the value are spaces)
36h 10 FAT12... junk Reserved. ('.' = spaces)
Here comes the FAT starting at 3Dh