Tape Spool Computers

Are we sitting comfortably? Good

I first noticed this computer in The Invasion, in Internetional Electromatics reception when Zoe blew it up.

A little while later I spotted it in Ambassadors of Death too..... and then saw it a few more times. And then saw more than one together. There's at least FOUR, all different. Yes, I'll concede they could have been modified but there's four variants here appearing in a very short space of time together, two of which definitely reappear latter

Doctor Who
Tenth Planet
8-29 October 1966

This seems to be the only appearance of this one: tape spools in all 4 sections at the top, rounded windows over the tape spools.

Adam Adamant
D for Destruction
13 October 1966

The machine on the left is very similar to above, the only difference is it has squared windows.

The machine on the right has dials in it's upper windows.

Out Of The Unknown
Lambda 1
20 October 1966

This one has flashing lights in upper windows.

The Prisoner
Arrival
19 September 1967

Looks like the Out of the Unknown Lambda 1 one again.

The Avengers
Mission: Highly Improbable
18 November 1967*

The right one from Adam Adamant D for Destruction with the Dials

Doctor Who
The Invasion
2 November - 21 December 1968

This looks like the unit from Out of the Unknown Lambda 1/The Prisoner Arrival again, but the doors are now missing over the tape spools. Later evidence suggests this is a different unit!

Doctor Who
Ambassadors of Death
28 March - 2 May 1970

It's definitely the same one as The Invasion, lights in the top windows, no windows lower down showing white tape spools.

Now for some while I'd left it at that but Mister Rhys on Twitter prompted me to look further and it's a good job I did because come episode 2 it's been replaced behind the door by the similar unit with lights in the top half but with doors over black tape spools/mounts in the lower half, identical to the one in Out of the Unknown Lambda 1/The Prisoner Arrival.

To it's right is a unit with dials in the top half and red tape spools/mounts covered by doors in the bottom half. Charitably this could be the same one on the right in Adam Adamant D for Destruction/The Avengers Mission: Highly Improbable if they've changed the tape spools.

And to it's right there's the unit we saw in episode 1/The Invasion

But come episode 3 it changes again The same lights/door covered tape spools unit is still behind the door from Out of the Unknown Lambda 1/The Prisoner Arrival.

And the dials/red tape spools with doors is still to the right of that

But next to that there's a unit with dials in the top half and uncovered white tape spools in the bottom half now. Again charitably this could be the same one on the right in Adam Adamant D for Destruction/The Avengers Mission: Highly Improbable if they've changed the tape spools, but there's definitely two with dials now.

Episode 3 shows several of the doors and panels open after Taltalian's device goes off The far right unit

The middle unit

There's some more pictures of this room in the DVD photo gallery. Judging by the one behind the door, this was taken for episode 1:

However there's another photo, presumably taken at the same time, which shows all three of the other units down the far end of the room, which I don't think you see in the episode: dials & covered red spools in the middle, lights & covered black spools on the right and dials & open white spools against the far wall.

So to summarise:

1) White Tape spools top and bottom, doors over spools, rounded corners on the windows: Doctor Who The Tenth Planet.

2) Black Tape spools top and bottom, doors over spools, square corners on the windows: Adam Adamant: D for Destruction

3) Dials top, Black Tape spools bottom, doors over spools, square corners on the windows: Adam Adamant: D for Destruction, possibly Doctor Who Ambassadors of Death 2/3

4) Lights top, Black Tape spools bottom, doors over spools, square corners on the windows: Out Of The Unknown Lambda 1 , The Prisoner Arrival, Doctor Who Ambassadors of Death 2/3

5) Lights top, White Tape spools bottom, NO doors over spools, square corners on the windows: Doctor Who The Invasion, Doctor Who Ambassadors of Death 1 & 2

6) Dials top, Red Tape spools bottom, doors over spools, square corners on the windows: Doctor Who Ambassadors of Death 2/3

7) Dials top, Black Tape spools bottom, NO doors over spools, square corners on the windows: Doctor Who Ambassadors of Death 2/3

So a minimum of four units, which we see in various combinations in Ambassadors of Death. That's the minimum there can be with assumptions about parts being swapped round made.