Puzzle 34 of 100

Gate order

Goal

Make Y low while B is high, or while A and C are both high. The die is narrow: draw each strip across all three gate lines without a break.

Die: 9 by 16 squares
Layers: Metal, Polysilicon, Contact, N active, P active, N well
Inputs: A, B, C
Output: Y
Supply: VDD
Ground: GND

Go to the solution

New in this puzzle

The order of the gate lines

Both strips cross the gate lines in the same order. An order works when every two neighboring transistors meet at a node they share in the circuit, in the N strip and in the P strip alike.

Hint

Choose the order of the gate lines so that each strip runs from contact to contact without a break. B must stand at one end; with B between A and C, the P strip would break in two. The inputs may cross other gate lines on their way, since metal passes over polysilicon.

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 34, Gate order, 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 34, Gate order, 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 34, Gate order, 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
Polysilicon42 squares
Contact14 squares
N active7 squares
P active14 squares
N well36 squares
Input padA, B, C
Output padY
Supply padVDD
Ground padGND
Squares you draw, change, or erase95 squares

About the drawing

The drawing uses 113 of the die's 144 squares.
Part of the drawing is in place when the puzzle opens. To finish it, paint 95 empty squares.
It forms 6 transistors: 3 N transistors and 3 P transistors. Each one is a place where polysilicon crosses active silicon.
14 contacts join metal to the polysilicon or active silicon under it.

Starting drawing for puzzle 34, Gate order, on a numbered grid. — The drawing when the puzzle opens. The dashed outline marks the squares the solution changes.