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Drawing the screen: DrawBoxTop

[NES version, Bank 7]

Name: DrawBoxTop [Show more] Type: Subroutine Category: Drawing the screen Summary: Draw the top edge of the box along the top of the screen in nametable buffer 0
Context: See this subroutine in context in the source code References: This subroutine is called as follows: * ClearDrawingPlane (Part 1 of 3) calls DrawBoxTop * TT66 calls DrawBoxTop
.DrawBoxTop LDY #1 ; Set Y as an index into the nametable, as we want to ; draw the top bar from column 1 to 31 LDA #3 ; Set A = 3 as the tile number to use for the top of the ; box (it's a three-pixel high horizontal bar) .boxt1 STA nameBuffer0,Y ; Set the Y-th entry in nametable 0 to tile 3 INY ; Increment the column counter CPY #32 ; Loop back until we have drawn in columns 1 through 31 BNE boxt1 RTS ; Return from the subroutine