> Опеннетные эксперты не могут доказать различия.

Опеннетным экспертам для этого нужно всего лишь глянуть в код, если уж сами с асмом знакомы лишь по слухам или laba.asm ...

https://github.com/microsoft/MS-DOS/blob/main/v4.0/src/DEV/V...

;    BIOS Parameter Block (BPB)                    ;
;-----------------------------------------------------------------------;
;This is where the characteristics of the virtual disk are established.
;A copy of this block is moved into the boot record of the virtual disk.
;DEBUG can be used to read sector zero of the virtual disk to examine the
;boot record copy of this block.
BPB     LABEL    BYTE        ;BIOS Parameter Block (BPB)
BPB_SSZ    DW    0        ;number of bytes per disk sector
BPB_AUSZ   DB    1        ;sectors per allocation unit
BPB_RES    DW    1        ;number of reserved sectors (for boot record)
BPB_FATN   DB    1        ;number of File Allocation Table (FAT) copies
BPB_DIRN   DW    0        ;number of root directory entries
BPB_SECN   DW    1        ;total number of sectors
                ;computed from buffer size and sector size
                ;(this includes reserved, FAT, directory,
                ;and data sectors)
BPB_MCB    DB    0FEH        ;media descriptor byte
BPB_FATSZ  DW    1        ;number of sectors occupied by a single FAT
                ;computed from BPBSSZ and BPBSECN
BPB_LEN    EQU    $-BPB        ;length of BIOS parameter block
BPB_PTR    DW    BPB        ;BIOS Parameter Block pointer array (1 entry)