> Back when I asked about the HP 3000, someone mentioned that it > processed data in blocks. What exactly does that mean? How does it > work?

I think the comment you're talking about was directly related to HP3000 full screen editors; these generally need a HP terminal that's capable of block-mode operations. This means that the terminal is capable of simple on-screen editing tasks by itself, and transmits a bunch of changes to the computer only when the computer needs to ask for the accumulated changes. This is very different than the mindset in the microcomputer and Unix world, where it is expected that the main CPU will want to devote attention to each and every keystroke typed by every user, and then the main CPU will devote all its effort (for a little while) to echoing this single character. This simply isn't the way things are done on mainframes and "heavy-duty" mincomputer OS's. Tim.