Which RT-11 for an 11/03

Sorry for the delay in my answer. I was out of town for the last 36 hours, so I just noticed this thread. For maximum flexibility, I would suggest V05.03 of RT-11. It is just about the most widely available and has the benefit of probably being completely legal to use on a non-commercial basis with SimH. V04.00 of RT-11 will probably run equally well, but obviously without some of the many additional features found in V05.03 of RT-11. In addition, you might want to check even later versions of RT-11, all of which still run on a PDP-11/03 CPU. Under V05.03 of RT-11, you can use either distributed Unmapped Monitor, RT11SJ or RT11FB. The size will be larger than from V04.00 of RT-11, but I suggest that the additional features are more than worth while. Since you have all 32 KW or memory or 64 KB, you will not have any problem booting RT-11. If you have any specific questions using Ersatz-11 with a PDP-11/03, just ask. That will make sure that the configuration and the boot device is set up correctly. Just for practice, you might try using Ersatz-11 with V05.03 of RT-11 with SET CPU 03. You will find that Ersatz-11 is trivial to use and that it supports emulation of all types of disk drives including TU-58, RK05, RL02 and SCSI, named, respectively, DD:, RK:, DL: and DU:, the same as DEC names them. Be warned that after you practice with Ersatz-11, you may find that an LSI-11, also called a PDP-11/03, is a bit slower than running with Ersatz-11, even on a 486. My experience with just a 750 MHz Pentium III is that RT-11 runs about 15 times as fast as a PDP-11/93. On a current I7 from Intel, I expect speeds more than 100 times as fast as a PDP-11/93. If you provide some of the information requested below, a version of RT-11 might be suggested which is a better fit. Otherwise, my assumption at present is that you want to use RT-11 since it is the only reasonable choice out of RT-11, RSX-11 and RSTS/E, although I am reasonably sure that RSTS/E can't run on a PDP-11/03. Further, you want to run RT-11 to be able to show that you can run RT-11 on the PDP-11/03 hardware that you have. That is quite different from the original reason a PDP-11/03 system was purchased, namely to run specific application programs which were able to run under RT-11. If I am incorrect, please let me know and advise otherwise. It does sound like you have the Heath Kit version of the hardware. If so, then you probably don't have a hard disk drive. A complete list of the actual hardware will be helpful. In addition, even more important from my point of view is why you want to use the hardware that you have to run RT-11 (most likely because it will not run anything else very easily) and then which specific application programs will be run after you are successful in getting RT-11 to run. Just as important is how you will interface with the PDP-11/03 and move the results from the PDP-11/03 to either printed output or a system that can share the results via the internet. Jerome Fine