PDP-11 memory question

Do you know if the application programs are using extended memory? If so, they gain much more than they loose, especially if they IOPAGE is not required - and even more so if they can use more than one window. As I stated in another post, RT11XM allows the user to request all the addresses from 20000 to 177776 (56 KBytes) to be set up in extended memory while still keeping PAR0 in the normal physical space from 00000 to 17776. This restriction is essential when an ISR (Interrupt Service Routine) is required. Otherwise, if the program uses memory in the normal manner (MACRO.SAV is a good example), the use of VBGEXE automatically sets the program up COMPLETELY in extended memory and makes all 64 KBytes available for code and especially data or tables. And providing sufficient additional extended memory is available, more extended memory can still be used as well - although the two are rarely combined since once a program starts to use extended memory, it usually does everything for itself. Note that VBGEXE probably can't be used in RT11XM when the program uses VIRTUAL arrays since I seem to remember that one of the upper PARs is required. So there are some limitations. Sincerely yours, Jerome Fine