From: Bob Shannon <bshannon(a)tiac.net> Killdal did say that DEC OSs (TOPS, OS8 and RT11) were the inspiration. However, one place where CP/M was not like RT-11 was the file system as CP/M did dynamic allocation with fragmentation where RT-11 does not support fragmented files. All RT-11 files (OS8 too) are contigious. In that respect RT-11 file system is most identical to NS* DOS but the NS* dos command structure and IO are must unlike RT-11. Internally RT-11 and CP/M are very dissimilar save for some underlying concepts such as an overlayable monitor, a modular resident IO subsystem and file handler. Allison