INT 10h,  05h (5)        Set Active Display Page

    Sets the active display page.

       On entry:      AH         05h
                      AL         Display page number

       Returns:       None

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

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                         Legal Page Values (AL)

               Video Mode                   LegalPages
                   00h                         0-7
                   01h                         0-7
                   02h                         0-3
                   03h                         0-3
                   04h                          0
                   05h                          0
                   06h                          0
                   07h                          0
                   08h                          0
                   09h                          0
                   0Ah                          0
                   0Dh                         0-7
                   0Eh                         0-3
                   0Fh                         0-1
                   10h                         0-1
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       Notes:         The contents of a display page are not destroyed
                      when the current display page is changed. In fact,
                      you can write to an inactive page, then switch to
                      it--thereby producing fast screen updates.

                      Use Service 0Fh to determine the current active
                      display page.