PCalc — An Interview with James Thomson
James Thomson explains how PCalc began in 1992, survived major Apple platform transitions, and remained a one-time purchase.
PCalc began in 1992 and has continued across generations of Apple hardware and operating systems. For My Mac Apps Story, I asked James Thomson what inspired it, what has kept it going since 1992, and how he has maintained it as a one-time purchase.
Interview by Ighor July for Reverse Everything.
Interview
Ighor July
What originally inspired you to create PCalc?
James Thomson
It was two things really. Mainly, I wanted a small self-contained app project to learn how to program the Mac. Also, I wanted a scientific calculator that did hex and binary to help with my coursework at university, and the built-in calculator back in 1992 was very simple.
Ighor July
What have been the greatest technical challenges involved in maintaining it across so many generations of Apple hardware and operating systems?
James Thomson
The actual code to do the calculations has been pretty straightforward to move between platforms. It was originally written in Pascal, but was converted to C/C++ in the late 90s and that’s quite portable. That code has been through three processor transitions, 68K -> PPC -> Intel -> Apple Silicon. The tricky part has been maintaining the user interface code, because Apple changes a lot each year - particularly on iOS.
Ighor July
What motivates you to continue developing and supporting PCalc after so many years?
James Thomson
Stubbornness, mainly :) Really, it’s still a good app to keep up with the changes each year, and keep learning. But, I want to keep it going. It’s been 34 years, so I don’t feel I can really stop now! Maybe when I get to 42 years. Plus, it has provided a good income, and it’s nice to be able to pay the bills.
Ighor July
PCalc has remained a true one-time purchase without being replaced by a separately sold new edition or moving to a subscription. What has enabled you to keep supporting existing customers under this model for so long?
James Thomson
From the developer side, I can see the justifications for subscriptions. Consistent, regular income would certainly be nice, rather than somebody buying a copy on day one of the App Store in 2008 and not paying anything else for nearly 20 years. But from a user perspective, I also really dislike subscriptions. Particularly for utility apps like PCalc. So, as long as new users keep buying copies, I don’t want to go there!
Ighor July
How has user feedback influenced its development? Were any important features or decisions based directly on user requests?
James Thomson
I maintain a document of every single feature request I’ve been sent, and try to keep track of what is frequently asked for and do those if I can. But I also do things that I want to add for myself. Support for RPN was a very popular request, and that’s why I added it. Editing button layouts though was something I wanted though, because I was creating all the different layouts by editing XML files directly, and that was very tedious. So, I made the editor, and the polished it up for everyone to use.
Ighor July
What advice would you give to independent developers who hope to maintain and support their apps for ten years or longer?
James Thomson
The easiest thing is to make something because you actually want to use the app yourself. Don’t just make something because you think it will make money. If your heart is not in it, you will get bored of it easily!
This interview is part of the developer interview series connected to My Mac Apps Story, Part 3.