[HECnet] Tops-20 ANONYMOUS FAL Preliminary Testing Results/DAP Query

That is an extremely difficult question to answer; they all had their quirks and advantages, which is not surprising given that they targeted very different markets.? As a whole, I would say that the quality of DEC's documentation was the same on all the platforms; I found it easier to wade through than IBM's VM/CMS docs. In terms of raw capacity, probably the later mainframe operating systems would be the best choice as these most approximate what is available today on commercial platforms (with the clear exception of the graphics interface).? What matters is the address space and functionality: 1. VMS started out on a 32 bit platform as a high super-mini computer.? DEC soon grew this into low mainframe class with the VAX 8650 series, the Alpha being a completely modern platform. VMS is an acquired taste; some people think DCL is great and others... 2. Tops-10 started as a mainframe platform and was eventually rewritten to have symmetric multi-processing.? The command interface is simple enough.? The process paradigm is limited in that there is a one-to-one mapping of one process per job.? The address space had been limited to 256K, but I think they may have done Extended Addressing.? I believe TCP/IP may have been available from a 3rd party vendor. 3. Tops-20 is more modern, having a multi-process per job architecture and a 30 bit address space.? Many Unix programs are easily ported.? It ran the most networking protocols, including TCP/IP.? It is quite easy to learn due to the COMND% interface, which provides completions, guiding, prompting and recognition. There was a time when there were more of these systems on the ARPAnet then Unix.? I have been looking to write an IP6 interface after I complete some more items on my To Do list. But the mini-computer operating systems are just plain cool.? It is amazing what they squeezed into the PDP-8's 12 bit address space and PDP-11's run some of the most interesting collection of OS's that I've ever seen. It really all depends on what you feel like playing with; it's a profitable learning experience all around.