On Jun 5, 2014, at 12:47 PM, Johnny Billquist <bqt at softjar.se> wrote: ... It don't. Believe me, I've seen this, and investigated it years ago. When you have a real PDP-11 running on half-duplex 10Mb/s talking to something on a 1GB/s full duplex, the PDP-11 simply can't keep up. Makes sense. The issue isn t the 10 Mb/s Ethernet. The switch deals with that part. The issue is that a PDP-11 isn t fast enough to keep up with a 10 Mb/s Ethernet going flat out. If I remember right, a Unibus is slower than Ethernet, and while a Q22 bus is slightly faster and could theoretically keep up, a practical system cannot. paul