AmigaDOS taught me so much about computing. For whatever reason I was drawn to using Ed for writing C on the Amiga, which prepared me for vi later on. And the

AmigaDOS taught me so much about computing. For whatever reason I was drawn to using Ed for writing C on the Amiga, which prepared me for vi later on. And the fact that AmigaDOS was a preemptive multitasking OS got me thinking about race conditions between tasks early on. I still fondly recall spending many hours with a debugger disassembling code in the ROM to better learn how things worked. I even ended up writing my own version of exec.library later on that ran in real mode on x86 (with preemptive task switching) along with a few device drivers for the serial port, console and floppy. Ah, the good times learning how to program as a kid!