Previous Part: Hacking "ESP8266 Black Board T5" Part 1 - Blinky on Keil Lets now move to SDCC, because SDCC is free and the free version of Keil has limitations. We will also move away from Windows to Ubuntu 64 bit Installing SDCC on your Ubuntu PC Download 64 bit snapshot from: http://sdcc.sourceforge.net/snap.php#Linux The archive file would be named something like: sdcc-snapshot-amd64-unknown-linux2.5-20180712-10467.tar.bz2 Download it to your ~/Documents directory Then execute the following commands from the same directory (~/Documents) where you have placed the downloaded archive: tar xjf ../sdcc-snapshot-amd64-unknown-linux2.5-20180712-10467.tar.bz2  cd sdcc  sudo cp -r * /usr/local This will install sdcc binaries into: /usr/local/bin/ header files into: /usr/local/share/sdcc/include/ non-free header files into: /usr/local/share/sdcc/non-free/include/ library files into: /usr/local/share/sdcc/lib/ non-free library files into: /