This reference manual consists of two parts. The first (sections 1 through 6) is intended for those who are either interested in the ITS 1.5 time sharing monitor for its own sake or who wish to write machine language programs to run under it. Some knowledge of PDP-6 (or PDP-10) machine language is useful in reading this part. The second part (sections 7, 8, and 9) describes three programs that run under ITS. The first program (DDT) is a modified machine language debugging program that also replaces the "monitor command" level (where the user is typing directly at the monitor) present in most time-sharing systems. The remaining two (PEEK and LOCK) are a status display and a miscellaneous utility program. It should be remembered that the McCulloch Laboratory PDP-6 and PDP-10 installation is undergoing continuous software and hardware development which may rapidly outdate this manual.
