I have been following the Operating System development tutorial on http://www.brokenthorn.com. Right now I'm trying to setup the BIOS parameter block with this code:
jmp loader
bpbName db "NubOS",0,0,0
bpbBytesPerSector: DW 512
bpbSectorsPerCluster: DB 1
bpbReservedSectors: DW 1
bpbNumberOfFATs: DB 2
bpbRootEntries: DW 224
bpbTotalSectors: DW 2880
bpbMedia: DB 0xF0
bpbSectorsPerFAT: DW 9
bpbSectorsPerTrack: DW 18
bpbHeadsPerCylinder: DW 2
bpbHiddenSectors: DD 0
bpbTotalSectorsBig: DD 0
bsDriveNumber: DB 0
bsUnused: DB 0
bsExtBootSignature: DB 0x29
bsSerialNumber: DD 0xa0a1a2a3
bsVolumeLabel: DB "MOS FLOPPY "
bsFileSystem: DB "FAT12 "
However, when I try to open the disk using the ImDisk driver for virtual floppies, it says that the drive needs to be formatted. Is the code I'm using correct?
Try a short jump: the sector begins with jmp short loader, followed by nop, then go bpbName through bsFileSystem, then loader: and all your code and then the last 2 bytes of the 512-byte sector being 0x55 and 0xAA. These two must be at offsets 510 and 511 respectively.