This is the HTML5 / javascript version of the HP-21 microcode emulator. The HP-21 was a basic scientific calculator from the 1970s.
Microcode means that it runs exactly the same way as the original; with the same precision as, and any quirks of, the original. It doesn’t just behave the same or produce the same results, it does that and gets those – because it works the same way too.
This version runs in a browser which means it works on any platform. You can use it on a Windows desktop, a Mac or a Linux computer. You can also use it on a phone (Apple or Android) or a tablet. It is written in HTML5 to work on just about any modern browser. It should look the same, work the same and behave the same; regardless of where you run it.
Features
- runs the original microcode
- runs on any device
- looks like the original
- Scientific functions (log, y^x, sin, cos, tan, etc)
- Has a single memory and storage register arithmetic
- Under 250KB in size, even less for the ZIP
Advanced Features
- Can be fully used without any of the advanced features
- Allows you to step or trace through the microcode to see what it is doing and how
- Allows you to adjust battery voltage reading to run the “low battery” microcode
Un-features
There’s a lot that’s great about an application that runs in a browser – you can pretty much run it on anything. But, browsers do bring some limitations with them too:
- You can’t read or write directly from or to your device file system, though this is more an issue for programmable calculators.
- You need internet access (or to have had it at least once)(or get the ZIP)
Downloading & Installing
It is a HTML5 application. That means you don’t even have to download it or install it. You can run it online anytime you want to. If you want to run it without access to the internet, you can choose the “install” option. That is a different link but it installs just as easily. As you use it, it saves a copy of everything it needs from the web and then, when you’re offline, it just runs from the local copies. There’s no extra steps at all (I think of it as a “zero-click install”). You still have the choice: use it online or have a copy with you.
Pick a link: use it or install it .
Buying a copy
The internet isn’t perfect. Things change. Perfectly good and useful things disappear or change. If you buy a copy, you’ll always have it. It won’t be in a browser cache that might get cleared. It won’t get updated automatically to remove features you liked or to add things you don’t. You get a snapshot in time and you get to keep it like that forever. If you buy a copy you get a ZIP with all of the needed files and you can install it on any computer you want.
Buying a copy also throws a few dollars my way and supports more work like this. If you like it and want to say thank you, buy a copy. If you like it a lot, buy two. You can buy a copy below:
More Information
This is part of the HP21 topic.
If you want to see if it’s any good, just click the “use it” or “install it” links above. That way you can play with it for free for as long as you like.
As with my other HTML5 microcode emulators, tap the display (LED digits) to bring up more options. On the hp21u it looks like:
Menu
Advanced
