Puzzle 28 of 100

Two gates, one pair of inputs

Goal

Make Y the NAND of A and B, and Z their NOR. The NAND gate is drawn.

Die: 13 by 26 squares
Layers: Metal, Polysilicon, Contact, N active, P active, N well
Inputs: A, B
Outputs: Y, Z
Supply: VDD, VDD
Ground: GND

New in this puzzle

Rows that share a rail

A row of cells can be drawn upside down under another, with its N transistors near the shared GND rail and its P transistors near a second VDD rail. Gate lines pass under the shared rail from one row to the next.

Hint

Draw the NOR gate in a second row below the first, upside down, so that the two rows share the GND rail. Continue the polysilicon lines of A and B under the GND rail into the lower row.

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 28, Two gates, one pair of inputs, 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 28, Two gates, one pair of inputs, 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 28, Two gates, one pair of inputs, 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

Metal89 squares
Polysilicon48 squares
Contact17 squares
N active10 squares
P active20 squares
N well72 squares
Input padA, B
Output padY, Z
Supply padVDD, VDD
Ground padGND
Squares you draw, change, or erase66 squares

About the drawing

The drawing uses 171 of the die's 338 squares.
Part of the drawing is in place when the puzzle opens. To finish it, paint 64 empty squares and change 2 drawn squares.
It forms 8 transistors: 4 N transistors and 4 P transistors. Each one is a place where polysilicon crosses active silicon.
17 contacts join metal to the polysilicon or active silicon under it.

Starting drawing for puzzle 28, Two gates, one pair of inputs, on a numbered grid. — The drawing when the puzzle opens. The dashed outline marks the squares the solution changes.