That's amazing, I wish any of my math books had that; we would probably see a lot more young programmers these days. I can seriously say that the only reason I even got into programming was discovering TI-Basic in 7th grade (although the habits it taught me had to be slowly unlearned as I started using a real language ;)
Well, the entry barriers to programming were actually lower in the 1980s. Pretty much every home computer came with a flavor of BASIC built right in to ROM or at the worst bundled with it on a disk. Anybody with a TI-99/4A, C64, various Apples, Atari 400/800/ST, or many others could jump right in to that kind of programming.
What's the equivalent nowadays? Windows doesn't really come with any programming environment. There's no standard for those math books to write towards. Yeah, there's plenty of free compilers for any language, but the funnel from even knowing they exist, to having a reason to get one, then finding it, and downloading and installing, gets pretty lengthy and technical for your average seventh-grader or whatever.
Heck, I would argue that TI calculator BASIC is the closest thing we have to a universally available development environment for secondary students today.
Every desktop of laptop OS I know of comes with at least one JavaScript interpreter installed.
The real problem is the growth of phones and tablets as preferred client devices; while the JS interpreter is still there, it becomes a challenge to enter and run the code.
To some extent the problem is our options are too rich, we've gone from flavours of basic to everything being available since all machines have a browser. One kid might use Scratch, another JavaScript, another GameMaker.
