9front's manuals will teach you the basics, the actual basics of CS (plan9 intro if you know to adapt yourself, too). These are at /sys/doc. Begin with rc(1), keep upping the levels. You can try 9front in a virtual machine safely. There are instructions to get, download and set it up at https://9front.org .

Write servers/clients with rc(1) and the tools at /bin/aux, such as aux/listen. They already are irc clients and some other tools. Then, do 9front's C book from Nemo.

On floats, try them at 'low level', with Forth. Get Muxleq https://github.com/howerj/mux. Compile it:

          cc -O2 -ffast-math -o muxleq muxleq.c
          

Edit muxleq.fth, set the constants in the file like this:

      1 constant opt.multi      ( Add in large "pause" primitive )
      1 constant opt.editor     ( Add in Text Editor )
      1 constant opt.info       ( Add info printing function )
      0 constant opt.generate-c ( Generate C code )
      1 constant opt.better-see ( Replace 'see' with better version )
      1 constant opt.control    ( Add in more control structures )
      0 constant opt.allocate   ( Add in "allocate"/"free" )
      1 constant opt.float      ( Add in floating point code )
      0 constant opt.glossary   ( Add in "glossary" word )
      1 constant opt.optimize   ( Enable extra optimization )
      1 constant opt.divmod     ( Use "opDivMod" primitive )
      0 constant opt.self       ( self-interpreter [NOT WORKING] )

Recompile your image:

       ./muxleq muxleq.dec < muxleq.fth > new.dec

New.dec will be your main Forth. Run it:

       ./muxleq new.dec

Get the book from the author, look at the code on how the Floating code it's implemented in software. Learn Forth with the Starting Forth book but for ANS forth, and Thinking Forth after doing Starting Forth. Finally, bacl to 9front, there's the 'cpsbook.pdf' too from Hoare on concurrent programming and threads. That will be incredibily useful in a near future. If you are a Go programmer, well, you are at home with CSP.

Also, compare CSP to the concurrent Forth switching tasks. It's great to compare/debug code in a tiny Forth on Subleq/Muxleq because if your code gets relatively fast, it will fly under GForth and due to constraints you will force yourself to be a much better programmer.

CPU's? Cache's? RAM latency? Muxleq/Subleq behaves nearly the same everywhere depending on your simulation speed. In order to learn, it's there. On real world systems, glibc, the Go runtime, etc, will take care of that making a similar outcome everyhere. If not, most of the people out there will be aware of stuff from SSE2 and up to NEON under ARM.

Hint: they already are code transpilers from Intel dedicated instructions to ARM ones and viceversa.

>How garbage collection works inside of the JVM?

No, but I can figure it a little given the Zenlisp one as a slight approximation. Or... you know, Forth, by hand. And Go which seems easiers and it doesn't need a dog slow VM trying to replicate what Inferno did in the 90's which far less resources.