LSR@MIT-XX.ARPA (12/31/83)
From: Larry S. Rosenstein <LSR@MIT-XX.ARPA> I am currently working on the Lisa Developer's Toolkit, so I can answer some of your questions about the machine and its development environment. The machine does use a segmentation memory management scheme, rather than demand paging. Code segments are automatically swapped in on demand; we experimentally determined a few 68000 instructions that are restartable, and our OS detects code faults, swaps in the segment, and continues the process. (This approach means that the machine does not have to be waiting for the code to come in, but can start up another process.) The same approach does not apply to data segments, however, because there are too many types of instructions that access data. The principal development language is PASCAL with some assembler. (C should be available sometime in 1984.) The development environment (called the WORKSHOP) should be available now. In order to write full Lisa-like applications, however, you need the TOOLKIT which is not widely available yet. (We have given advance copies to certain developers.) The toolkit implements a generic Lisa application that automatically handles the things that all applications should do. (Like opening from an icon, scrolling, splitting, zooming, etc.) Programmers just implement application-specific behavior. This approach means that applications do not have to worry very much about the details of the Lisa user interface (the source code is mostly independent of the user interface implementation). Also, several applications can share a small kernel of code, which in the Lisa environment will make switching between applications faster. Unfortunately, I cannot take any questions over the net, since this is probably the last time I will have access to it. You can try calling or writing at the address below. Larry Rosenstein Apple Computer 10455 Bandley Drive M/S 2P Cupertino, California 95014 408-973-3552 -------