henry copeland: Is this the birth of the computer user (vs the programmer)? pllqt.it/ydwc4WClip 30: In this segment Doug distinguishes between the Service System and the User System. The ARC team distinguishes overall man-computer system into a dichotomy between two systems, the service system and user system.The Service System is what appears at the terminal, the organization of software and hardware the system gives to me, the set of tools and capabilities available when I click on the screen. The user system is what is beyond that. Given these tools, how do we use the links, what are the conventions for leaving messages? How do we use the NLS capabilities to do work? The methods, procedures, skills, and specific concepts people use are all developed in coordination with the kind of tools they have available.