org    100h

Start:
        mov     ax, 4f02h        ; VESA set mode
        mov     bx, 101h         ; 640*480 8bpp (256 colors)
        int     10h

        mov     dx, 0xA000       ; Screen memory starts at segment 0A000h in real mode
        mov     es, dx
        call    setWindow

StartAgain:
        xor     dx, dx            ; DX = Window number?
        mov     [color], 0
MainLoop:
        ;push    dx
        call    setWindow
        inc     [color]             ; next color to next bank
        mov     al, [color]
        call    static_

        ;pop     dx
        cmp     dx, 4             ; 4 = total banks  (0 to 4 = 5)
        je      StartAgain        ; reset
        inc     dx                ; next Window or next Bank?
        mov     ah, 1h            ; just keyboard
        int     16h
        jz      MainLoop

        ; exit

        ret

setWindow:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; AX = 4F05h = Display Window Control
;; BH = 00h select video memory window
;;      01h get video memory window
;; BL = 00h Window A
;;      01h Window B
;; DX = window address in video memory (in granularity units)
;; 
;; Return:
;; DX = window address in video memory (in gran. units).
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
        mov     ax, 4F05h
        xor     bx, bx
        int     10h
     ret


; paints each Window (banks?)
static_:
        stosb              ; copies AL value (color) to ES:DI, and adds DI.
        inc     bx
        test    bx, bx
        jnz     static_
     ret


color    db 0    

Hello
Here there is a utility for Vbe test that i wrote some time ago
for Dos/Win98/Xp,
Vista and Windows 7 report wrong data but you can try.

there is a dword that tells you the base linear adress of your frame buffer.

org 100h
        mov ax, 0xA000
        mov es, ax

        ;mov ax, 4F00h            ; get info
        ;mov di, VbeInfoBlock
        ;int 10h

        ;call checkSucessful

        mov ax, 4F02h            ; set mode
        mov bx, 11Bh
        int 10h

        call checkSucessful

        mov ax, 4F01h            ; get modeinfo
        mov cx, 11Bh
        mov di, VbeModeInfoBlock
        int 10h

        call checkSucessful

  ; plot pixel

        mov eax, [pixel.y]
        mul [VbeModeInfoBlock.BytesPerScanLine]
        push eax
        mov eax, [pixel.x]
        mul [VbeModeInfoBlock.BitsPerPixel]
        pop ebx
        add eax,ebx
        mov dword[VbeModeInfoBlock.PhysBasePtr+eax],0x000FFFF

  ; exit

exit:   mov ax,1
        int 16h
        int 20h

pixel:
  .y dd 50
  .x dd 50

; ### functions ###

  hex2str:
        ; EAX = value
        ; EDI = buffer
        mov     edx,eax
        mov     ecx,8
    .format_hex:
        rol     edx,4
        movzx   ax,dl
        and     al,0x0f
        cmp     al,0x0a
        sbb     al,0x69
        das
        mov     word[edi],ax
        inc     edi
        loop    .format_hex
        mov     byte[edi],'$'
        ; EDI = string
        ret

  print:
        mov ax,3       ; back text mode
        int 10h
        ; DX = string
        mov ah,9       ; print
        int 21h
        ret

  checkSucessful:
        ; AX = VBE status
        cmp  ax, VBE_SUCESSFUL
        je   @f
        mov  dx, vberror
        call print
    @@: ret

; ### VARS ###

  vberror db '  VBE not supported!$'
  buf     rb 16


  VBE_SUCESSFUL = 004Fh

; structs

VbeInfoBlock:
  .VbeSignature      db 'VESA'      ; VBE Signature
  .VbeVersion        dw 0300h       ; VBE Version
  .OemStringPtr      dd ?           ; VbeFarPtr to OEM String
  .Capabilities      db 4 dup (?)   ; Capabilities of graphics controller
  .VideoModePtr      dd ?           ; VbeFarPtr to VideoModeList
  .TotalMemory       dw ?           ; Number of 64kb memory blocks
  ; Added for VBE 2.0+
  .OemSoftwareRev    dw ?           ; VBE implementation Software revision
  .OemVendorNamePtr  dd ?           ; VbeFarPtr to Vendor Name String
  .OemProductNamePtr dd ?           ; VbeFarPtr to Product Name String
  .OemProductRevPtr  dd ?           ; VbeFarPtr to Product Revision String
                     db 222 dup (?) ; Reserved for VBE implementation scratch
  ; area
  .OemData           db 256 dup (?) ; Data Area for OEM Strings

VbeModeInfoBlock:
  ; Mandatory information for all VBE revisions
  .ModeAttributes        dw ? ; mode attributes
  .WinAAttributes        db ? ; window A attributes
  .WinBAttributes        db ? ; window B attributes
  .WinGranularity        dw ? ; window granularity
  .WinSize               dw ? ; window size
  .WinASegment           dw ? ; window A start segment
  .WinBSegment           dw ? ; window B start segment
  .WinFuncPtr            dd ? ; real mode pointer to window function
  .BytesPerScanLine      dw ? ; bytes per scan line
  ; Mandatory information for VBE 1.2 and above
  .XResolution           dw ? ; horizontal resolution in pixels or characters
  .YResolution           dw ? ; vertical resolution in pixels or characters
  .XCharSize             db ? ; character cell width in pixels
  .YCharSize             db ? ; character cell height in pixels
  .NumberOfPlanes        db ? ; number of memory planes
  .BitsPerPixel          db ? ; bits per pixel
  .NumberOfBanks         db ? ; number of banks
  .MemoryModel           db ? ; memory model type
  .BankSize              db ? ; bank size in KB
  .NumberOfImagePages    db ? ; number of images
                         db 1 ; reserved for page function
  ; Direct Color fields (required for direct/6 and YUV/7 memory models)
  .RedMaskSize           db ? ; size of direct color red mask in bits
  .RedFieldPosition      db ? ; bit position of lsb of red mask
  .GreenMaskSize         db ? ; size of direct color green mask in bits
  .GreenFieldPosition    db ? ; bit position of lsb of green mask
  .BlueMaskSize          db ? ; size of direct color blue mask in bits
  .BlueFieldPosition     db ? ; bit position of lsb of blue mask
  .RsvdMaskSize          db ? ; size of direct color reserved mask in bits
  .RsvdFieldPosition     db ? ; bit position of lsb of reserved mask
  .DirectColorModeInfo   db ? ; direct color mode attributes
  ; Mandatory information for VBE 2.0 and above
  .PhysBasePtr           dd ? ; physical address for flat memory frame buffer
                         dd 0 ; Reserved - always set to 0
                         dw 0 ; Reserved - always set to 0
  ; Mandatory information for VBE 3.0 and above
  .LinBytesPerScanLine   dw ? ; bytes per scan line for linear modes
  .BnkNumberOfImagePages db ? ; number of images for banked modes
  .LinNumberOfImagePages db ? ; number of images for linear modes
  .LinRedMaskSize        db ? ; size of direct color red mask (linear modes)
  .LinRedFieldPosition   db ? ; bit position of lsb of red mask (linear modes)
  .LinGreenMaskSize      db ? ; size of direct color green mask  (linear modes)
  .LinGreenFieldPosition db ? ; bit position of lsb of green mask (linear modes)
  .LinBlueMaskSize       db ? ; size of direct color blue mask  (linear modes)
  .LinBlueFieldPosition  db ? ; bit position of lsb of blue mask (linear modes)
  .LinRsvdMaskSize       db ? ; size of direct color reserved mask (linear modes)
  .LinRsvdFieldPosition  db ? ; bit position of lsb of reserved mask (linear modes)
  .MaxPixelClock         dd ? ; maximum pixel clock (in Hz) for graphics mode
                         db 189 dup (?)  ; reserved: remainder of ModeInfoBlock
    

        mov dword[VbeModeInfoBlock.PhysBasePtr+eax],0x000FFFF
    

and then, create a descriptor for the vesa frame buffer

Read standard carefully.

mov edi, VbeModeInfoBlock.PhysBasePtr
mov dword[edi],0xFFFFFFF ; i suposed to be 0,0 pos