I've used Piklab (http://piklab.sourceforge.net/) on and off since 2008 or earlier. I'm not sure why it isn't mainstream Debian. A PIC (http://www.microchip.com/) is a really tiny, cheap single-chip computer. They're RISC, have their own instruction sets, there are various assemblers and compilers for them. I like the PIC12F683 as a minimum, it's an 8-pin IC, draws about 100 ua, has 2K of program memory, sells for about $1.50. Most have some A/D converter and PWM with configurable pins. I think that's what Arduinos use, never had one.
Piklab is an IDE which can drive some hardware programmers to write the program to the chip. Microchip has a Windows version called MPLAB which Piklab partially emulates under unix. The hardware programmers can run from simple circuits you can build to pre-built devices you plug into a USB port.
I'm running it in a VNC session to a Pi here. It isn't necessary to program in assembly, you can get at least C and BASIC. I'm looking at adding a solar-powered 433 MHz reporting method to an existing homebrew anemometer. Very simple, just count pulses and radio the result back to the house once a minute as maybe a 16 or 32 bit word with a check bit.