Puzzle 24 of 100

An OR gate

Goal

Make Y high while A or B is high. The inputs arrive at pads on the top edge, above the VDD rail.

Die: 14 by 15 squares
Layers: Metal, Polysilicon, Contact, N active, P active, N well
Inputs: A, B
Output: Y
Supply: VDD
Ground: GND

New in this puzzle

Under the rail

Polysilicon passes under metal without joining it, so an input pad above the VDD rail can feed a gate line directly. A contact beside the pad joins the pad to the polysilicon.

Hint

Build a NOR gate and follow it with an inverter. Place a contact just under each input pad and run polysilicon from it down under the VDD rail; the line continues as a gate.

Solution

This is the game's reference drawing for the puzzle. It meets the goal and passes the design rules. Other drawings can pass as well.

Top View of the solved die for puzzle 24, An OR gate, with the Side View below it. — Top View of the solved die, captured from the game. Paths that carry a high level at the moment shown are lit. The Side View below cuts through the row between the dashed lines.

The game window in Isometric View with the solved die for puzzle 24, An OR gate, the guide, and the scope. — The whole game window in Isometric View. The scope on the right compares each output with its target band, and the message above it confirms that the drawing passes.

Solution drawing for puzzle 24, An OR gate, drawn on a numbered grid with every layer in its game color and pattern. — The solution on the grid. Squares are numbered from the top left corner, so you can count them. The dashed outline marks the squares you draw, change, or erase; the rest is drawn when the puzzle opens.

Legend

Metal67 squares
Polysilicon37 squares
Contact16 squares
N active8 squares
P active16 squares
N well52 squares
Input padA, B
Output padY
Supply padVDD
Ground padGND
Squares you draw, change, or erase100 squares

About the drawing

The drawing uses 126 of the die's 210 squares.
Part of the drawing is in place when the puzzle opens. To finish it, paint 98 empty squares and change 2 drawn squares.
It forms 6 transistors: 3 N transistors and 3 P transistors. Each one is a place where polysilicon crosses active silicon.
16 contacts join metal to the polysilicon or active silicon under it.

Starting drawing for puzzle 24, An OR gate, on a numbered grid. — The drawing when the puzzle opens. The dashed outline marks the squares the solution changes.