This is so much easier. You are implementing printf on page 5 and it can handle formatted output to the screen for integers, hexadecimals, and strings. Minix eventually gets around to the write system call but even then it is actually just a way of sending bytes from a buffer to a file descriptor. To a what? That is a lot more complexity for, in some ways, less functionality. For write, you still have to write printf on top.

The Tanenbaum book is great but it is a particle physics textbook compered to this OS cookbook.