diff --git a/src/groovylight/geom.py b/src/groovylight/geom.py
index dcf384d..d658c7c 100644
--- a/src/groovylight/geom.py
+++ b/src/groovylight/geom.py
@@ -3,6 +3,8 @@
 
 from enum import Enum
 from dataclasses import dataclass
+from typing import Self
+from math import ceil, log2
 
 
 @dataclass(frozen=True, order=True)
@@ -13,7 +15,7 @@ class Coord:
 
     x: int
     y: int
-    
+
     def __post_init__(self):
         if self.x < 0 or self.y < 0:
             raise RuntimeError("x and y must both be >= 0")
@@ -34,6 +36,26 @@ class BBox:
     def contains(self, c: Coord) -> bool:
         return c > self.topleft and c < self.bottomright
 
+    @property
+    def width(self) -> int:
+        return self.bottomright.x - self.topleft.x
+
+    @property
+    def height(self) -> int:
+        return self.bottomright.y - self.topleft.y
+
+    def intersects(self, other: Self) -> bool:
+        ## other leftmost edge is right of our rightmost edge
+        x1 = other.topleft.x > self.bottomright.x
+        # our leftmost edge is to the right of other rightmost edge
+        x2 = self.topleft.x > other.bottomright.x
+        # other top edge is below (greater than!) our bottom edge
+        y1 = other.topleft.y > self.bottomright.y
+        # our top edge is below other bottom edge.
+        y2 = self.topleft.y > other.bottomright.y
+
+        return not (x1 or x2 or y1 or y2)
+
 
 @dataclass(frozen=True)
 class DisplayDimensions:
@@ -44,6 +66,10 @@ class DisplayDimensions:
 
     length: int
     height: int
+    mux: int = 2  # number of lines driven at once.
+
+    def addr_bits(self) -> int:
+        return ceil(log2(self.height / self.mux))
 
 
 class DisplayRotation(Enum):
@@ -68,7 +94,7 @@ class DisplayRotation(Enum):
 
 
 @dataclass(frozen=True)
-class _DisplayString:
+class DisplayString:
     """Internal class to represent a string of HUB75 displays.
 
     position: (X,Y) coordinates of the local top-left of the display
@@ -81,6 +107,7 @@ class _DisplayString:
     position: Coord
     dimensions: DisplayDimensions
     rotation: DisplayRotation
+    # TODO: encode muxing
 
     @property
     def bbox(self) -> BBox:
@@ -103,10 +130,13 @@ class _DisplayString:
         """Checks if the given coordinate is inside this display."""
         return self.bbox.contains(coord)
 
+    def intersects(self, box: BBox) -> bool:
+        """Checks if the given BBox intersects with this display"""
+        return self.bbox.intersects(box)
+
 
 class DisplayGeometry:
-    """Represents a display based on several strings in different positions.
-    """
+    """Represents a display based on several strings in different positions."""
 
     def __init__(self, *, strict: bool = False):
         self.strict = strict