I am attempting to enhance a program which runs under RSTS/E, RTEM-11, RT-11 and TSX-Plus. Thus far, I have managed to support these enhancements for all but RTEM-11 due to the lack of documentation on RTEM-11. When I requested help with supporting such programs under RSTS/E, John Dundas provided a reference document which cleared up many questions. Does anyone know of a document (and its link if it is on the internet, especially at bitsavers) which describes the support provided by RTEM-11 for programs which also run under RT-11? From the comments that I have seen, the RT-11 operating system is run under RTEM-11 with special "hooks" to interface to RTEM-11. If my understanding is correct, then all of the RT-11 EMT requests supported by an RT11SJ monitor will also be available when running under RTEM-11. There are also two other specific questions that I suspect have a simple answer: (a) How much memory does a user program have which runs under RTEM-11? My assumption is that a user program has approximately the same size of memory available when running under RTEM-11 as it would when running under the RT11SJ monitor on a PDP-11 with 64 KBytes of physical memory which usually (when no additional device drivers are present) ends up being approximately 48 KBytes or an address range from 0 to about 120000 octal. (b) Whereas RT-11 actively supports the ability of device drivers to be LOADed and UNLOADed at any time based on which devices are in active use, RSTS/E and TSX-Plus require the device drivers of any device that is active to be LOADed at all times. It would be an assumption on my part, but I tend to assume that under RTEM-11, any available devices are already LOADed by the actual operating system that controls the CPU. Specifically, if a user program performs the .DStatus RT-11 EMT request for an available device, the 3rd word of the device driver information will always be non-zero which specifies that the device driver in question is always in memory and that a .Fetch RT-11 EMT request would be redundant. Can anyone provide any documentation sources? If anyone knows the answer to the approximate size of memory available to a user program running under RTEM-11 and / or the answer concerning the LOADed status of a device driver, it would be greatly appreciated. Jerome Fine