Not to mention that home computers had a different set of devices to handle as well - eg. cassette drives, floppy disks and later small hard disks - often with

Not to mention that home computers had a different set of devices to handle as well - eg. cassette drives, floppy disks and later small hard disks - often with their own controllers which had to be interfaced with the system somehow (using isolated I/O on CPU's like the Z80, and memory-mapped I/O on others like the 68000).