Early Calculating Devices

   I'm an admitted geek. I love sci-fi, fantasy, comic books, horror and roleplaying games. One of my more dweebish pursuits has been early calculating devices. These include the abacus, the slide rule and the addiator. These devices predate the modern electronic calculator and, for the most part, are little used today. Some countries, like Japan, still make extensive use of their version of the abacus, the soroban. 

  In this pic, you can see my 23 column soroban, an Arithma addiator, an Exactus pre-decimal English currency addiator and a Pickett N600-ES six inch slide rule. I've playlisted several YouTube videos demonstrating how to use these devices. Here are some videos.

  Despite their age, these devices still have their uses. I can use the Arithma to help keep track of my hit points in roleplaying games. The Exactus can keep track of money in Cthulhu by Gaslight and The One Ring games since both use a monetary system based on pre-decimal English currency. The Exactus separates currency into pounds (libra), shillings (solidus), pence (denarius) and farthings. 4 farthings equal a penny. 12 pennies (or pence) equals 1 shilling and 20 shillings equal 1 pound sterling. That was the English monetary system until Feb. 15th, 1971-Decimal Day. 

  Most of these devices were relatively easy and cheap to acquire. The Exactus was much more expensive. I got it from an Australian eBay seller. It came with a case and complete instructions. I've made it a point to preserve the instruction booklet and put it away in order to keep it intact.

  While I known how to use these devices to some degree, I've by no means mastered them. The Arithma and Exactus are easy to use. I can use the slide rule to a decent degree but I haven't used some of the more complicated scales. I can add and subtract on the soroban, but I haven't mastered multiplication, division, square or cube roots yet.