11/1/22

Every day I use the HP-12C calculator to quickly crunch numbers and perform financial functions, for a few reasons:

• The HP-12C is one of the only two calculators approved for use during the CFA (Chartered Financial Analyst) exams... it's good practice

• I've become so accustomed to using RPN (Reverse Polish Notation) that I can't use any other calculator without constant error and frustration... I assume it's a fairly niche problem

• I continue to be impressed by just how good of a calculator it is, despite its design being now over 40 years old

Little did I know that the last point, a harmless admiration for the ingenuity of engineers past, was a gateway drug into the world of vintage calculators and history of computer science.

The next chapter in my downward spiral was the purchase of an HP-80, a machine touted as "The first hand-held calculator with business and finance functions," introduced in February 1973 (nearly 50 years old!). The included owner's manual starts with a step-by-step comparison of performing a simple internal rate of return calculation by hand vs with the HP-80. This initially struck me as odd- "Of course math on a calculator is easier than doing math by hand... why not show a more apples-to-apples comparison?"

Apple's first attempt at a computer was still four years away. Microsoft Excel was still over decade away. Like HP said, "There is no comparable tool available today!" I began wondering what obstacles you had to overcome to be a trailblazer in the early days of calculator/computer technology. What were the limitations? What body of knowledge was there to draw from? What could I come up with, if I was transported back in time to those early years...

And thus begins the journey to design and build my own calculator from scratch. The goal is to learn a bit about those pioneer days of computer engineering, solve interesting logic puzzles, and to gain some appreciation for the dedication and imagination that built the technology that runs the modern world. I know nothing about electrical engineering, very little about theoretical computer science, and just a bit about finance. With the HP-80 as a benchmark, let's see if I can design and physically build a financial calculator. I know I'm not the first, and I won't be the best, but I still think it will be a fun project.

At the time of writing, I have no idea where this hobby project will lead, if anywhere. If you're interested in learning along with me, stay tuned.

Next up:

Part 1: What is a number?

Sources:

https://www.hpmuseum.org/hp80.htm

http://www.vintagecalculators.com/html/hewlett-packard_hp80.html