# The Brain Puzzler(tm)

There is only one solution, designed and programmed by the computer.
170 sequential movements of the rods will return all 8 wedges to the IN position. The rods slide through 8 different levels. Each level is cut-out differently than the other seven levels. When a rod slides in, it re-aligns all the levels into a new pattern. This re-alignment will unlock some of the rods and re-lock others. No more than 2 rods are movable at any given time, and only one is the correct move.

Can you discover the correct sequence?
If you succeed, can you bring all 8 wedges back out again? (Another 170 sequential moves.) A Clue: The program is based on the Gray Binary System.

For solution, Send 50 cents and a self-addressed stamped envelope .

```No. 2225 The Brain TM (C) 1989,
Mag-Nif Inc.,
8820 East Avenue, Mentor Ohio 44060
```

--The Brain Puzzler Box

Introduction

Along with the catch phrases "Can you discover the solution?" and "A thinker's challenge...", that was all that there was on the pink and shades-of-red box that my new toy came in. It winked at me from the recesses of the puzzle aisle in the local Fred Meyers when I was shopping for some birthday gifts. My brother gets Legos, and that girl from school gets a Battle Bots action toy. I got it, intrigued by the design of the gadget, interest piqued by the mention of Gray Code.

Appearance

I opened it on the way to the car, and (pleasingly free from complex wrapping paraphenalia save a single folded piece of cardboard) out came "The Brain Puzzler." It's a roughly cylindrical gadget, radially symmetric, with eight pins sticking out the top, numbered from 1 to 8, and eight flanges sticking out from the base, corresponding to the eight pins.

The base is maybe an inch high, made of black plastic. At the top are the flanges, and right below them a sort of tray to support them. The bottom half-inch of the base is of a smaller radius, giving a stepped effect to the whole assembly. The base itself is only a hollow cylinder - you can turn the whole thing upside down and see the grooves that the flanges run in. From the base, a much narrower (2cm diameter or so) pillar runs up to the top of the puzzle.

The puzzle itself consists of a stack of 8 clear plastic discs with slots cut in them. The topmost disk has a pattern of axial slots for the pins to slide in, but as you get deeper down the patterns become much more complex - it's hard to tell how much so, because of the distortion of looking through many layers of plastic. All of the disks save for the top one (which is bonded to both an outer cylinder of clear plastic and to the center pillar) are free to rotate.

The pins stick out about an inch from the top of the stack of discs, and the flanges stick out about half an inch when they're out - when they're in, they're flush with the tray of the base. The pins have a range of motion corresponding to the slot size - from an inch from the center to about a half-centimeter from the perimeter of the puzzle.

Functionality

The operation of The Brain Puzzler is relatively simple. I would suggest that you keep it on a flat surface, though - the pins tend to drift when you're holding it at an angle, and they need to be fully engaged for the discs to line up properly for the next move.

Anyway. There's just one primitive to this puzzle - toggling a pin. The pins have two positions - in, along their slot towards the axis, and out, along their slot towards the circumference. The flange corresponding to each pin is, in fact, the place to which said pin is attached, so that when the pin is out, the flange is out, as well.

Through an ingenious mechanism of slanted grooves, moving the pins changes the internal state of the discs, so that simply by twiddling two pins you can reach new states.

Pins that are locked can wiggle a little bit but not really move. Pins that are unlocked slide freely under their own weight, but the puzzle does not give the impression of flimsiness.

First off, I want to strongly emphasize that there are SPOILERS AHEAD

Read no further unless you want the guts of this intriguing little puzzle laid bare at your feet.

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Well, you're still with us. That's good. Onto the fun!

This puzzle is especially interesting to all you computer programmers out there because it is basically a Gray Code counter. Gray code for those of you not up on your comp sci (I had to look it up in my digital logic text book...) is a variant of the normal binary counting method. Normal binary goes 001, 010, 011, 100, etc. The problem with this is that in some cases you can end up with intermediate states like (when going from 011 to 100) 101, if your circuitry isn't perfectly synched. Gray Code gets around this problem by making only one bit at a time change - so you go 001, 011, 010, 110, 111, etc.

So what we really have here is an 8-bit gray code binary counter. Pretty nifty, eh? And the coolest thing about binary counting is that it's got a cool rhythm about it. Gray code is ideally suited to counting by fingers because it only involves changing one finger at a time.

The puzzle itself is easy - you just use the pins as bits (pin 1=lowest bit), and count in grey code. Assume out equals zero and in equals one. It's easy enough, especially when you realize that it guides you through out - the only legal move is the one that doesn't undo what you just did.

Now, if you'll excuse me, I need to count to 170 again...