Outils pour utilisateurs

Outils du site


Table des matières

INT 0x21 - 0x30 - Get DOS version (DOS 2+)


reg value descr
AH 0x30


reg descr
AL Major version (2 → x)
AL Minor version (in hundredth decimal)
BH 0xFF: indicates MS-DOS, only if OEM vendor chooses to identify
0x00: indicates PC-DOS
BL:CX 24bit OEM Serial number if BH = 0xFF

Notes & Comments

  • for an example DOS version 2.1 returns AL=2 and AH=10
  • DOS versions prior to DOS 2.0 return zero in AH and AL
  • DOS version 4.0 and 4.1 usually return the same value of 4.00
  • the OEM serial number is a rarity, though some older OEM DOS versions implemented this feature
  • the OS/2 compatibility box returns 10.10 for OS/2 1.1, 10.20 for OS/2 1.2, etc…
  • when testing for version, a specific test can often cause your code to not work in following versions of DOS. It is often better to test for a version number greater or equal to the minimum rather than a specific version number where possible


back2root/ibm-pc-ms-dos/interrupts/int_21/int_21_30.txt · Dernière modification : 2024/01/19 23:23 de frater