INT 10H 4f04H - Save/Restore SuperVGA State

 Expects: AX    4f04H
          CX    bit flags indicate which states to save/restore
          DL    SubFn number:  00H = Get save-state buffer size
                               01H = Save SuperVGA state
                               02H = Restore SuperVGA state
          ES:BX addr of buffer (subfns 01H and 02H only)
          ──────────────────────────────────────────────────────────────────
 Returns: AX    VESA status: AH=0 means successful (else failed)
                             AL=4fH means function supported
          BX    size of save-state buffer in 64-byte blocks (subfn 00H only)
          ──────────────────────────────────────────────────────────────────
    Info: Use this function to save the current state of the SuperVGA
          system and to later restore that state.

       CX describes what you want to save or restore as bit flags:
           1
          ┌5───4┬3┬2┬1┬0┐
          │0...0│s│c│b│h│
          └─────┴╥┴╥┴╥┴╥┘ bit  mask
                 ║ ║ ║ ╚══► 0: 01H save/restore video hardware state
                 ║ ║ ╚════► 1: 02H save/restore video BIOS data state
                 ║ ╚══════► 2: 04H save/restore DAC state; color regs
                 ╚════════► 3: 08H save/restore entire SuperVGA state

   Notes: ■ To use this function: first decide what info you need to save
            and set the bits of CX and set DL to 00H to see how much memory
            you'll need.  Then allocate a buffer of the needed size (it is
            BX * 64 bytes lone).  Set ES:BX to point to the buffer and use
            DL=01H to save the info into the buffer.

          ■ The layout of the return information at ES:BX is not documented
            and will be OEM-dependent.

See Also: SVGA
          VESA/SVGA BIOS Services
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