On Mon, Mar 18, 2024 at 9:57 AM Clem Cole wrote: > The DZ11 is an eight-port mux (with short pinned modem control and no DMA > - both causing issues). > I'm pretty sure that when we beta tested the VAX-11/780 in the summer of 1977 it had a DZ11. We only had a few LA36 printing terminals on it so we never saw any issues with it. Not so when I started work at DEC in 1980. The VAX-11/780 I worked on had IIRC three DZ11a supporting 24 terminals. The lack of DMA was a big issue. We had to run our VT52s no faster than 300 baud or it brought the system to its knees. -Paul W.