On 2011-07-14 21.22, Mark Wickens wrote: OK Johnny, So to not appear too one tracked, and maybe draw the subject a little more towards your heart ;) Since my recent acquisition of various PDP handbooks I've decided to delve the world of PDPs a little now I've been able to read up on the (somewhat confusing) model numbers. Could I have recommendations of where to go in terms of an emulator (assume linux based), which model and operating system? What I'd like to do is play with some of the languages, especially but not exclusively APL, I don't know what software there is out there, whether licenses are required, etc. I'm guessing this is all very much before the SPL started... Thanks for the help, Mark. Those are not neccesarily easy questions to answer. As for emulator, simh is free, but I'd say e11 is better. So it depends on your preferences. :-) They both probably work well enough for your needs, though. What you want to emulate, though, is something with all the "features" that you might want to use, which means lots of memory, split I/D-space and supervisor mode. This means: 11/44, 11/53, 11/7x, 11/8x or 11/9x machines. As for operating system, that depends on your preferences. I can't really say what you should go with. An additional complication is that there aren't free licenses for some of the stuff, and it's still commercial products. Johnny