Anita

This is Anita! I found her at a car boot sale and after some haggling and transfer of funds she was allowed to come home with me.

British made by the Bell Punch Company, the original model of Anita was the world's first all-electronic desktop calculator. Obviously this particular one is a slightly later model, released in 1971 - 10 years after the original.

Anita speaks in Reverse Polish when it comes to calculations, so my initial attempts at communicating with her resulted in some confusing exchanges. Luckily she came with the original instruction manual and I soon had her behaving properly. You must enter one number, press the ENTER 1ST NO button, enter the second number and then press the button for the operator (PLUS, MINUS etc).

The display is made up of 10 Nixie tubes. These are like vaccuum tubes; glass tubes filled with an inert gas. Each contains a wire mesh anode and 10 cathodes that light up to form the digits 0 to 9. The decimal point is represented by separate lamps, one between each digit, although sadly one of them doesn't light up any more. In fact, one of the other ones lights up instead, so it may be that the lamp works but there is a short circuit in there somewhere.

The LSI in the name stands for Large Scale Integration. Yes, this thing is old, but it actually contains integrated circuits! 1000s of transistors forming a miniaturised circuit in the surface of a thin layer of semiconductor material. I must admit I didn't know that integrated circuits were available in consumer products as early as 1971. When I first saw this thing, I was sure it must be late '70s.

Although Anita can count, unfortunately she is a bit poorly and has some trouble with her tubes. Displaying either a 4 or a 7 results in both the 4 and 7 cathodes lighting up simulateously, which makes understanding her answers slightly tricky! This affects each of the tubes, so I think it's a problem with the circuitry driving them rather than something wrong with the tubes themselves.

I don't know if Anita is worth much. There are certainly none on eBay, so she's a rare find that's for sure. I have a sneaky suspicion that her organs are worth more on the black market than she is as a whole. The Nixie tubes are quite sought-after by retro boffins who make them into clocks and other gubbins.