I guess I can do one of these a day or so. I've collected some novelties over the years.

First up is a Curta mechanical calculator. Before electronic calculators became a thing, these were the best portable calculators in the world. Notably, they were the calculator of choice in rally car sports.

They work by a series of helical gears that act as registers. A series of internal gears and value assignment switches apply an adjustable number of incrementations to those gears, multiplying gears and the tracking gears, once per "grind." The result is output as a number on top of the device. The "clear register" function is lifting the top ring, which releases the reverse lockout on the gears and a clockwise turn on the ring then resets them to their zero state.

They were designed by Curtz Herzstark, partly before WWII and partly while he was imprisoned in a Nazi concentration camp. He had filed a patent for it in 1938, shortly before his family's manufacturey became a weapons factory. During his imprisonment, in addition to nearly starving to death, he completed his plans for manufacturing of his calculator.

It had fun names like the, "pepper grinder," and "math grenade."

Since we're limiting this to things on my desk I can't do any more deep cuts out of my calculator collection, but this one is still somewhat interesting.

The HP 32S was my friend throughout university, it replaced the 15c I used before which does not live on my desk. The notable thing about the 32s is the fact it's an RPN calculator. RPN calculators are the best way to have friends never ask to borrow your calculator. The exchange will start by them asking to use it, you saying sure, and them handing it back a few minutes later without saying a word.

There's two kinds of people in this world. People who go "wtf" in an interview when asked to create a calculator program using a stack, and people who were oddballs and for whatever reason used reverse polish notation devices.

For those not familiar, rather than entering values into the calculator in "10+10" fashion, you instead provide it a compositional set of values until an operation is provided (10,10,+) at which point it executes. The why is, this type of operation allows the calculator to more naturally process operations, and eliminates the need for parenthesis which makes the operations less error prone in practice and easier to track.

The 32s had a 4 year run before being replaced by the 32SII. In the same way using a Curta will give you a significant understanding of how radix computations and floating points work. Using an HP 32s (or any of its predecessors) will do the same for algebraic functions, because you had to program them yourself using a basic label address system that also had subroutine support.

Kids who grew up with graphing calculators don't know how good you had it 😋