Function 3306h Get MS-DOS Version

mov ax, 3306h ;Get MS-DOS Version

int 21h

mov MajorV, bl ;major version number (05h for version 5.0)

mov MinorV, bh ;minor version number (00h for version 5.0)

mov RevisionNum, dl ;revision number in bits 0 through 2

mov VersionFlags, dh ;version flags

Get MS-DOS Version (Function 3306h) returns the MS-DOS version number, the MS-DOS revision number, and version flags specifying whether MS-DOS is in the high memory area (HMA) or in read-only memory (ROM).

Parameters

This function has no parameters.

Return Values

The BX and DX registers contain the following information:

Register

Contents

BL	The major version number—for example, 05h for version 5.0.
BH	The minor version number—for example, 00h for version 5.0.
DL	In the low three bits, the revision number. All other bits are reserved and set to zero.
DH	The MS-DOS version flags. The contents may be a combination of the following values:

Value

Meaning

DOSINROM (08h)	If set, MS-DOS runs in ROM; otherwise, MS-DOS runs in RAM.
DOSINHMA (10h)	If set, MS-DOS is in the high memory area; otherwise, MS-DOS is in conventional memory.

All other bits are reserved and set to zero.

Comments

This function returns the actual MS-DOS version number rather than the version number set by the setver command for the program.