Pardon my ignorance, but does the Alto multi-task between user programs? If the answer to that question is affirmative, how does the machine cope with simultaneously running two programs that load different custom microcode? Does it load and unload and reload at every context switch? Or does it simply not multi-task?
The Alto is a "personal computer" and only runs one program at a time. The operating system provides primitive task management (sort of like threads) so the operating system can for instance process network packets while a program is running, or a program can contain multiple tasks. Thus, a program can load the microcode it needs when it starts up and doesn't need to worry about conflicts.
This task management is entirely orthogonal to the 16 tasks that are running at the microcode level to refresh the display and handle I/O devices.
