[dandrake]

Interesting. As I recall, we never thought of the paging as a big innovation: just what had to be done in order to do anything in a memory space of 128K bytes. You can bet that it presented an interesting challenge in adding the UNDO feature to the existing system. BTW it seems to me that AutoCAD never got much recognition for its technical innovations. One very early example: It was almost certainly the very first program which could run equally well with or without the 8087 floating-point chip (ahem - except for speed!), needing no special user configuration or anything. Credit where credit is due: Not a Walker idea, but an inspiration of one of the unsung super-hackers among the original crew.