SIMH is the Computer History Simulation Project, an Internet-based collective aimed at preserving computing's heritage by simulating systems of historic interest. Started in 1993, the project now encompasses more than 20 systems, including the DEC PDP-1, PDP-4/7/9/15, PDP-8, PDP-11, and VAX; the Data General Nova and Eclipse; the HP 2100 series; the Interdata 16b and 32b series; the IBM 1401, 1620, 1130, and System/3; and many others. SIMH has provided a vehicle for running the earliest versions of Unix (including the first 32b port), for reconstructing lost software systems such as XVM/DOS, and extending the development life of "nearly current" systems like 2.11BSD for the PDP-11. SIMH is constantly being expanded to include new systems, additional capabilities for existing simulators, and greater interactivity with "real world" peripherals such as networks and graphics.