Along with MIPS. The significance of which is that it led to a lot of network gear using one of these 3 architectures. Now most network data planes are in ASIC and increasingly these BE ISAs are being supplanted by ARM but for a long time it held out as a bastion for PPC in particular.

ARM still has big-endian mode for this niche. Modern ARM cores even have dynamically switchable endian for data

That's awesome. Thanks for sharing.

Little endian is the vast majority of stuff today due to the dominance of x86, but back when big-endian ruled the day. That's why network byte order is big-endian.

VAX and PDP-11 were also little-endian.

Were those the first byte-addressable architectures? If they were you think they'd have had a bigger influence.

No. They were both enormously influential, though.

IBM S/360 got there before the PDP-11 (1964 vs 1970) -- but it probably also wasn't the first.

https://en.wikipedia.org/wiki/IBM_System/360

Unix was developed on a PDP-11 (I ignore the first, embryonic, version on an 18-bit PDP-7 because that version was in assembler and couldn't really do much more than host Space War). The real, grown-up, version of Unix with proper virtual memory was developed on a VAX (as part of BSD Unix). Sockets also came from BSD Unix, developed on VAX.

IEEE floating-point is largely based on their floating-point format -- but it is incompatible and has a number of extra bells and whistles that William Kahan insisted on.

They were also used for developing various experimental programming languages.

Windows NT is in many ways a reimplementation of DEC's VMS operating system for the VAX.

The PDP-11/74 was an early experimental 4-way SMP machine -- that quickly taught the OS developers that they didn't know as much as they thought about how to write SMP software!

Of course, this makes sense - thank you!