diff --git a/js/defs.js b/js/defs.js
index da7f095..1159af4 100644
--- a/js/defs.js
+++ b/js/defs.js
@@ -4,6 +4,7 @@ export const DIRECTIONS = {
     north: {
         movement: [0, -1],
         bit: 0x01,
+        index: 0,
         action: 'up',
         left: 'west',
         right: 'east',
@@ -12,6 +13,7 @@ export const DIRECTIONS = {
     south: {
         movement: [0, 1],
         bit: 0x04,
+        index: 2,
         action: 'down',
         left: 'east',
         right: 'west',
@@ -20,6 +22,7 @@ export const DIRECTIONS = {
     west: {
         movement: [-1, 0],
         bit: 0x08,
+        index: 3,
         action: 'left',
         left: 'south',
         right: 'north',
@@ -28,6 +31,7 @@ export const DIRECTIONS = {
     east: {
         movement: [1, 0],
         bit: 0x02,
+        index: 1,
         action: 'right',
         left: 'north',
         right: 'south',
diff --git a/js/format-c2g.js b/js/format-c2g.js
index 6faf993..ef2ef36 100644
--- a/js/format-c2g.js
+++ b/js/format-c2g.js
@@ -462,7 +462,34 @@ const TILE_ENCODING = {
                 }
             },
             encode(tile) {
-                // FIXME implement
+                let direction_offset = DIRECTIONS[tile.direction].index;
+                if (tile.gate_type === 'not') {
+                    return 0 + direction_offset;
+                }
+                else if (tile.gate_type === 'and') {
+                    return 4 + direction_offset;
+                }
+                else if (tile.gate_type === 'or') {
+                    return 8 + direction_offset;
+                }
+                else if (tile.gate_type === 'xor') {
+                    return 12 + direction_offset;
+                }
+                else if (tile.gate_type === 'latch-cw') {
+                    return 16 + direction_offset;
+                }
+                else if (tile.gate_type === 'nand') {
+                    return 20 + direction_offset;
+                }
+                else if (tile.gate_type === 'counter') {
+                    return 30 + tile.memory;
+                }
+                else if (tile.gate_type === 'latch-ccw') {
+                    return 64 + direction_offset;
+                }
+                else {
+                    return 0xff;
+                }
             },
         },
     },
@@ -612,8 +639,11 @@ const TILE_ENCODING = {
                     tile.arrows = arrows;
                 },
                 encode(tile) {
-                    // TODO
-                    return 0;
+                    let bits = 0;
+                    for (let direction of tile.arrows) {
+                        bits |= DIRECTIONS[direction].bit;
+                    }
+                    return bits;
                 },
             },
         ],
diff --git a/js/main-editor.js b/js/main-editor.js
index 6537805..91fda1f 100644
--- a/js/main-editor.js
+++ b/js/main-editor.js
@@ -1007,6 +1007,7 @@ const EDITOR_PALETTE = [{
     // - wires, wire tunnels        probably a dedicated tool, placing tunnels like a tile makes no sense
     // - canopy                     normal tile; layering problem
     // - thin walls                 special rotate logic, like force floors; layering problem
+    // - light switches
     // TODO should tiles that respond to wiring and/or gray buttons be highlighted, highlightable?
 }, {
     title: "Logic",
@@ -1045,7 +1046,7 @@ const SPECIAL_PALETTE_ENTRIES = {
     'logic_gate/nand':      { name: 'logic_gate', direction: 'north', gate_type: 'nand' },
     'logic_gate/latch-cw':  { name: 'logic_gate', direction: 'north', gate_type: 'latch-cw' },
     'logic_gate/latch-ccw': { name: 'logic_gate', direction: 'north', gate_type: 'latch-ccw' },
-    'logic_gate/counter':   { name: 'logic_gate', direction: 'north', gate_type: 'counter' },
+    'logic_gate/counter':   { name: 'logic_gate', direction: 'north', gate_type: 'counter', memory: 0 },
 };
 const _RAILROAD_ROTATED_LEFT = [3, 0, 1, 2, 5, 4];
 const _RAILROAD_ROTATED_RIGHT = [1, 2, 3, 0, 5, 4];