Passion project time! I love the HP-45 #calculator. It's beautiful on the outside, but I wanted to show people that it's beautiful on the inside, too. So, as a #coding & #retrocomputing challenge I wrote a simulator, & I'm now making it available to all. (Retweets welcomed.) 1/7 
The simulator was designed for the Z80-MBC2, a computer designed by @Just4Fun_J4Fun with a #Z80 processor running CP/M. (If you like #retrocomputing, do try it.) But after some tedious wrangling, I was able to write code which also compiled for Windows, Linux & MacOS. 2/7
I like the sense of retro-tech and (unfulfilled) futures which the terminal application provides: it's a #hauntological calculator. It's also flexible: you can change what's shown on the display &, for slower machines (say, an 8MHz Z80), you can run in minimal mode for speed. 3/7
Because I want hp45term to explain the genius of the HP-45's ROM code, I've kept my code as simple and clear as I could, & made sure that it includes copious & detailed comments throughout, explaining how the calculator processes the 2048 bytes of its ROM. #retrocomputing 4/7
And because the HP-45's ROM is so beautifully crafted, I've also included a new version of the disassembled ROM, to show what it's doing in each byte. hp45term itself includes a "heat map" to show how each key press is processed throughout the bytes of ROM.
#retrocomputing 5/7
#retrocomputing 5/7
Well, that's it. Here's the download link: sarahkmarr.com/hp45term.zip. I hope you enjoy it. There are help screens in the program, but if you're new to the HP-45 (or RPN) then start here: decadecounter.com/vta/pdf/HP-45%…. Oh, and yes, it does implement the 'secret' timer function. 6/7
Anyway, I'm not sure I have a huge retrocomputing or calculator-loving following, so retweets are most welcome, to reach those who might find hp45term of interest. Some hashtags: #computing #coding #z80 #calculator #retro #hauntology #mathematics #maths #math #retrocomputing 7/7
Bonus tweet: your reminder that other operating systems are available and—with a bit of know-how—supported by the application.
https://twitter.com/vmisev/status/1473407620073635845?s=20
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