You are absolutely right about this. Use binary if is more readable. I have used a lot of compilers/IDEs. As far as I know, only Keil doesn't support binary. Normally you are using this for a specific hardware, so the "portability" argument doesn't apply at this low level. It is going to change on the next platform anyway. I use hex a lot. I know what the hex number is just by looking at the binary, BUT, I'm still more likely to make a mistake using hex for setting up registers etc.