INT 10h,  0Fh (15)       Get Current Video Mode

Reports the current video mode, the number of character positions per
line in that video mode, and the current display page.

On entry:      AH         0Fh

Returns:       AL         Video mode
AH         Number of character columns per line
BH         Active display page number

Registers destroyed:      AX, SP, BP, SI, DI

                                                                          

Notes:         See Service 00h for a table of the video modes and
how to set the current video mode.

See also: INT 10h, 00h

INT 10h, 0Fh (15) Get Current Video Mode