Drawing the screen: DrawBitplaneInNMI

       Name: DrawBitplaneInNMI                                       [Show more]
       Type: Subroutine
   Category: Drawing the screen
    Summary: Configure the NMI to send the drawing bitplane to the PPU after
             drawing the box edges and setting the next free tile number
  Deep dive: Views and view types in NES Elite
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * DrawScrollFrames calls DrawBitplaneInNMI
             * DrawSpaceViewInNMI calls DrawBitplaneInNMI
             * LAUN calls DrawBitplaneInNMI
             * LL164 calls DrawBitplaneInNMI
             * RunDemoFlightLoop calls DrawBitplaneInNMI


.DrawBitplaneInNMI

 LDA #%11001000         ; Set A so we set the drawing bitplane flags in
                        ; SetDrawPlaneFlags as follows:
                        ;
                        ;   * Bit 2 clear = send tiles up to configured numbers
                        ;   * Bit 3 set   = clear buffers after sending data
                        ;   * Bit 4 clear = we've not started sending data yet
                        ;   * Bit 5 clear = we have not yet sent all the data
                        ;   * Bit 6 set   = send both pattern and nametable data
                        ;   * Bit 7 set   = send data to the PPU
                        ;
                        ; Bits 0 and 1 are ignored and are always clear
                        ;
                        ; This configures the NMI to send nametable and pattern
                        ; data for the drawing bitplane to the PPU during VBlank

                        ; Fall through into SetDrawPlaneFlags to set the
                        ; bitplane flags, draw the box edges and set the next
                        ; free tile number