The View From 30,000ft

Let's start with an overview of The Drof Computox, how it is set up for use and how to get into its guts. When packaged for storage, the Computox is a rather anonymous black wooden box measuring 42x43x58cm and weighing approximately 26kg.

The Drof Computox packed for storage

The Drof Computox name is printed in white on the front of the case using what looks to be Letraset.  There are handles on each side of the case which are a little too small given its mass, and four rubber feet on the bottom.  No sockets or controls are visible on any surface, just a keyhole in the middle of the top.

Setting Up The Computox

Next to the keyhole the case splits open across the top, then diagonally down each side and across the bottom at the front.

Computox case split line and key

Having unlocked the case, the front section lifts straight up and off the base.

Opening the enclosure

This exposes the main control panel and a storage bay for the two controllers. 

The open Computox base unit

One or both of the controllers can be plugged into sockets on the front of the main panel.  Once inserted they rest on the top of the case front and wooden pocket that they were stored in, this supports them and reduces stress on the connectors.

Controllers connected to the base unit

The game display is housed inside the front part of the case which was removed when opening the enclosure.  This protects the display and control panel when the Computox isn't in use.  As you can see the empty tic-tac-toe board is visible through a white plastic diffuser which is about 20cm on a side.  Also notice the large wooden tongue and socket in the middle of the bottom of the display unit.

The game display inside the front case

If the display unit is rotated 180 degrees from its packed orientation, the tongue slots into the hole that can be seen on the top of the main unit, and the socket plugs into a connector buried inside.  The Computox now stands 108cm tall.

The game display installed on the base unit

Finally, the mains power connector is plugged into a socket at the right of the front panel and the Computox is ready to be used, giving us this image of it from 2016.

The Drof Computox being played at the Museum of Computing in 2016

The Base Unit Control Panel

Looking at the main control panel in a bit more detail we can see the various game controls.

The main control panel

From top to bottom these are:

• In the first row, a second smaller diffuser window approximately 4.5cm across in the centre labelled "winner". Notice that because the case was open with sunlight behind it when this photo was taken the O symbol is visible in the window.
• The three pin power socket on the right 
• In the second row, two push buttons on the left labelled "O repeat" and "O start"
• A mechanical counter in the centre which currently reads "0553" 
• Two push buttons on the right labelled "mute" and "reset"
• In the third row, a cutout panel on the left and right that are kept in place by flat head screws (we'll investigate what hides beneath these later)
• A rotating power switch in the centre that is labelled "on" when in the vertical position

Like the outside of the case, all labels appear to be Letraset transfers.  Each label is either entirely upper case or lower case, never mixed case (I guess the printing budget was limited).

The player controllers are labelled X and O on the left and right respectively.  At the moment the socket that the X controller plugs into is not attached to the front panel and is floating around inside the case.  This may or may not have something to do with the Computox being retired as a museum exhibit.  Either way, hopefully it's something we can fix.

Given the labeling of controllers, the image of the Computox being used in 2016, and the "O repeat" and "O start" push buttons, it seems likely that when playing a single player game, the human plays X and the Computox plays O.

Getting To The Guts Of The Computox 

To get access to the mechanism of the Computox it's necessary to remove the game display and both controllers from the base unit.  Then four large machine screws at the bottom of the case sides can be undone.  At this point the outer shell of the case can be carefully lifted off the base using the handles on the side.

Removing the outer case

This exposes the machine's innards in all their glory.  At its heart the Computox comprises 47 relays and two uniselectors most of which are mounted on three metal frames.  This all seems to be telephone exchange equipment.  At the bottom of the case, between the frames and main control panel, is a power supply with a couple of transformers and what looks to be a metal rectifier.

The internals of the Drof Computox when viewed from the back

The wiring is very professional with lacing cord being used extensively to construct a loom that is then pinned to the case.  Great though this is, it's a bit worrying as it might make getting access to the back of the relays to buzz out the connections tricky.  However, that's a problem for another day, for now let's just enjoy this electro-mechanical beauty.

Relays baby! (and a uniselector)