TOOLCHAIN

Toolchain.  I run on linux, these examples are tested on linux, other
than subtle differences like rm vs del in the Makefile, you should be
able to use these examples on a windows or mac system.

My code is written to be somewhat generic, but the assembly and in
particular the linker script are specific to the gnu tools because
that is how the toolchain world works unfortunately.  Since everyone
can get the gnu tools, they are available for Windows, Mac and Linux,
but not everyone can or wants to use the pay-for tools (or free tools
that are specific to one operating system) these examples are written
and tested using a gnu tool chain.  My personal style is such that
this code tends to port across the various versions of the gnu tools
also it is not specific to arm-none-eabi, arm-none-gnueabi,
arm-linux-gnueabi and so on.  You may need to change the ARMGNU line
at the top of my Makefile or override the environment variable.

So, if you are running Ubuntu Linux or a derivative you might only
need to do this:

sudo apt-get -y install gcc-arm-none-eabi binutils-arm-none-eabi

Or you can go here and get a pre-built for your operating system

https://launchpad.net/gcc-arm-embedded

Or in another one of my github repositories you can get a build_arm
script

https://github.com/dwelch67/build_gcc

Which builds a cross compiler from sources.  Here again tested on
Linux (Ubuntu derivative) I used to use prior versions of this
script on Windows, but I gave up on maintaining that...This latter
build from the script is what I use as my daily driver arm toolchain.

Note that while the full sized Raspberry Pi's are ARM based as well
as the Pico, with some exceptions the full sized Raspberry Pi's use
a 64 bit ARM (aarch64) based toolchain and you need the 32 bit (aarch32)
for the Pico so you may still need to get a cross compiler toolchain.

I am very happy to see that they are showing the use of full sized
Raspberry Pi's as development platforms for the Pico.