These are the original VAXen. As stated before, the VAX was originally intended as an extension to the PDP-11. This and the popularity and name recognition of the PDP-11 is how the VAX-11 got its name. Also, it was somewhat backward compatible to PDP-11s running RSX-11. The original model was the VAX-11/780 which was a bit larger than a large refrigerator. Originally, they supported up to 8 Megabytes of RAM and later revisions could support up to 128 Megabytes. Like most other computers of it’s time it used a CUI or Character Based Interface. This means the display of all information was single font and text based. VMS 1.0 was the original operating system for it and not long after a 32-bit adaptation of Research UNIX v7 called 32V. Eventually DEC designed its own proprietary UNIX called Ultrix and it ran on the VAX-11 as well. Also 3BSD was designed for the VAX-11/780. The next model was the reduced cost/size VAX-11/750. VMS 2.0 was released to support it. The 750 was followed by the VAX-11/730 which only support up to 5 megabytes RAM and was the smallest VAX to date. The last model was the VAX-11/785 which was a faster version of the VAX-11/780. There were also a few multiprocessor version which emulation for is spotty at best.