Puzzle 42 of 100

One control signal

Goal

Make Y follow A while C is high, and keep its last level while C is low. This time there is no CN pad: make the inverse of C on the die.

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

Go to the solution

New in this puzzle

Making the inverse

A transmission gate needs a control and its inverse. An inverter makes the inverse from the control itself, so one input is enough.

Hint

Draw an inverter from C beside the transmission gate. Join its output to the P gate, and join C itself to the N gate. Polysilicon can pass under the metal columns at the ends of the transmission gate to reach its two gates.

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 42, One control signal, 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 42, One control signal, 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 42, One control signal, 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

Metal73 squares
Polysilicon42 squares
Contact16 squares
N active8 squares
P active16 squares
N well60 squares
Input padC, A
Output padY
Supply padVDD
Ground padGND
Squares you draw, change, or erase65 squares

About the drawing

The drawing uses 146 of the die's 256 squares.
Part of the drawing is in place when the puzzle opens. To finish it, paint 63 empty squares and change 2 drawn squares.
It forms 4 transistors: 2 N transistors and 2 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 42, One control signal, on a numbered grid. — The drawing when the puzzle opens. The dashed outline marks the squares the solution changes.