2001: The Memory Block Key

When Dave Bowman floats into HAL’s improbably huge “brain room” he carries a tiny key in one hand. And with this key he starts to unlock and eject the memory modules from HAL’s brain, one by one. Methodically at first, then trembling as HAL’s mind slowly breaks down.

Burg-Wächter lockblockers

Below each memory block aperture was a recessed square containing a keyhole. For a long time it wasn’t known what key was used, or if the production had made their own.

Then, in 2011, fellow Space Odyssey researcher Amadeus Prokopiak announced a discovery on the RPF forums. He had come across a matching key stem, which is still commercially available today.

The found part of the brain key was a German-manufactured Burg-Wächter lockblocker key with the head removed. There are four reasons why this discovery seems to be correct, though we have no written production notes or first-hand statements confirming it.

• The key is very unusual – it has a long cylindrical stem with tiny notches at the end for a tumbler lock.

• The key’s stem has a distinctive curved slot cut into either side.

• The upper part of the stem forms a long partial cylinder, meaning that the key is smooth and featureless when viewed from the top, except for the step down in stem diameter.

• The locks have an unusual downwards-pointing triangular recess at the top, above the slot.

What the heck is this thing?

The Burg-Wächter product is a very specialized device. It’s basically a brass cylinder designed to fit into the keyhole of an old-style lever tumbler mortice lock, not a pin tumbler lock. (lever locks use the kind of long-handled keys sometimes called “church keys”) The lockblocker’s chrome-plated key then locks the mortice cylinder in place, effectively blocking the keyhole.

Why would you do this? Well, let’s say you own a building, apartment, or flat, and want to lock the tenants out for some reason. But you don’t have enough time to call a locksmith to come and swap out the locks. (mortice locks are more time-consuming to swap than, say, the quick single-screw removal of a Euro cylinder lock) You could simply insert a lockblocker as a temporary, and instantly reversible, security measure.

Incidentally the German brandname can translate to “castle guard” (watchman).

The E 6 or E 7 Key?

For years it’s been presumed that a Burg-Wächter E 7 lockblocker/keyhole lock was used. This has a shaft that's 7mm in diameter. However, I believe that an E 6 (6mm) was used.

Specifically, a Burg-Wächter Zylinder-Schlüssellochsperrer (cylinder keyhole lock) model E 6/2 or SB 4271. The 2 simply means two keys come in the pack.

I showed photos to Burg-Wächter and they immediately suggested it was an E 6, owing to its subtly different proportions. I then compared the outline of the E 6 to 4K screenshots, and it does look closer to me than the E 7. (I bought copies of both) Finally, if you assume that the memory blocks were exactly 0.5 inches wide, then the lock recess would also have been 0.5" square. And the E 6 lock dimensions correspond to the screenshot closely, given this size. It's amazing what a difference that 1mm in diameter makes.

If E 7 locks had been used then the square recesses would have needed to be about 14.6mm or 0.57" wide. That corresponds to roughly 9/16", which seems unlikely to me since that dimension would also be the thickness of each transparent memory block.  Acrylic sheet was readily available in 1/4" and 1/2" thicknesses, but not an unusual size like 9/16". (Today it’d be the metric equivalents: 6mm and 12mm)

The handle

So the key part of the key has been identified. What about its large blocky aluminium handle? Everything points to this being production-made.

Basically the 2001 production team custom-machined the tapered aluminium block that the E 6 key shaft fit into. Amadeus Prokopiak created an aluminium block design that fits the E 7 well and looks quite good. His drawings have been taken and used by people to make 3D printed replicas which are widely sold online.

However, he did this work in 2011 or so, and therefore lacked one thing we have now — the 4K scan of the movie that was released on Blu-Ray UHD in 2018. That high-quality scan reveals far more detail than a standard DVD.

I took movie 4K screenshots and reverse-engineered my own brain room key from those known images, and came up with a slightly different design.

First, the scale of my key differs slightly because it's designed to fit the E 6 key. This affects a number of dimensions, particularly the square tip at the end. Second, I noticed that the sides of the flat grip section do not appear to be parallel, as in the Prokopiak design. The actual screen-used key grip seems to be tapered inwards.

This grip design makes sense, since of course the key might be operated by an astronaut wearing gloves. So a grip that flared out like this could be held more naturally.

The lock mechanism

The production team must have modified the locks. In the movie, our hero Dave Bowman is seen inserting the key into each lock, turning it counter-clockwise 90 degrees… then removing the key without rotating it back to vertical.

You can’t do that on a standard Burg-Wächter lockblocker. You can only remove the key when the lock is in the same rotational position as when it was inserted.

In order to use it to block a lock you insert the key, turn it counter-clockwise, insert the lockblocker into the lock, turn the key back to vertical, then remove the key.

Therefore the set builders must have modified each lock by removing all the internal pins. Which means, of course, that they no longer served as actual locks anymore – any E 6 key would have fit.

The lock recesses

While the real keys are chrome plated, the lock part of each lockblocker (the round head and cylindrical shaft) is simple brass.

But what colour were the recessed squares beneath the memory blocks? (the square surrounds into which the locks fit) Unfortunately, we don’t know. The only closeup shots are screengrabs from the movie, and they’re all lit with crimson light. I haven’t found a white light shot that's in colour - just black and white photos. There is white light from the brain blocks that reflects off the helmet and spacesuit in closeup shots, but the light is still heavily contaminated with red.

So. Were the squares brass to match the locks? Or were they aluminium, given the general preponderance of that metal in the 2001 sets?

I vote brass, since an aluminium plate with a recessed brass lock looks rather weird. They also seem subtly yellowish at a few points in the movie, when they’re primarily lit by white reflecting off the helmet, suggesting brass is correct.

Each brass square was recessed into the black surface. By roughly 1/16" (1.6mm) or so, which matches a commonly available thickness of Formica laminate. (some of the 2001 ship blueprints specifically call out Formica panels, but they don't specify the thickness)

This closeup view from a 4K scan has been processed to reveal some of the details, such as the characteristic Burg Wächter triangular recesses in the lock. I created this shot by combining a few dozen individual frames from the movie, averaging them out mathematically to reduce noise.

This shot also shows that the acrylic brain blocks weren't flush with the panel – they protruded out a small amount when they were in the installed position. Note that this shot doesn't prove whether or not the squares were actually brass, since the colour in this processed image is not accurate - I was working on clarity of detail, not colour-matching.

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