Puzzle 73 of 100

A data latch

Goal

Make Q follow D while EN is high. While EN is low, Q keeps the level D had when EN fell.

Die: 38 by 12 squares
Layers: Metal, Polysilicon, Contact, N active, P active, N well, Metal 2, Via
Inputs: D, EN
Output: Q
Supply: VDD
Ground: GND

New in this puzzle

One data input

A D latch sets when D is high and resets when D is low, so set and reset never act together. While EN is low it keeps the last level of D.

Hint

The set side already takes D. Feed the free input of the reset gate from the output of the set gate: while EN is high it is the inverse of D, so the latch sets when D is high and resets when D is low.

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 73, A data latch, 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 73, A data latch, 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 73, A data latch, 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

Metal173 squares
Polysilicon83 squares
Contact40 squares
N active32 squares
P active64 squares
N well140 squares
Metal 2106 squares
Via11 squares
Input padD, EN
Output padQ
Supply padVDD
Ground padGND
Squares you draw, change, or erase35 squares

About the drawing

The drawing uses 364 of the die's 456 squares.
Part of the drawing is in place when the puzzle opens. To finish it, change 35 drawn squares.
It forms 16 transistors: 8 N transistors and 8 P transistors. Each one is a place where polysilicon crosses active silicon.
40 contacts join metal to the polysilicon or active silicon under it.
11 vias join metal 2 to the metal under it.

Starting drawing for puzzle 73, A data latch, on a numbered grid. — The drawing when the puzzle opens. The dashed outline marks the squares the solution changes.