The PDP 11 was a very impressive computer in its day.
1975 - The represented the high end of architecture with the capacity for supporting the speed, addressing range and bandwidth required in large systems applications. It was the first to use cache memory.
PDP-11/05 and 11/10. The central processors for the PDP-11/05 and 11/10 were identical. The 11/05 was offered for the Original Equipment Manufacturer, while the 11/10 was designed for the end user. Both machines offered features not available on the earlier PDP-11/20, such as 4-level priority interrupt and multiple accumulators