On Thu, 6 Oct 1994, Dave McGuire wrote:

>   Hey there...you might wanna look into a DH-11 series mux for your
> serial lines, man.  The DZ's are nice but they'll kill your machine in
> a hurry.  They spew an interrupt on every character in or out of the
> board.  A DH uses DMA to plop the characters into a buffer and only
> interrupts once in a while.  They should be almost as cheap as a DZ
> now, too.  The one that I had the most experience with was the
> DH-11AD, which had 16 serial ports with full modem control, and was a
> standard 9-slot Unibus backplane full of boards plus a rackmounted
> DB25 distribution panel.  Very nice mux indeed.
> 

Not wanting to go too far off the subject at hand, but I must agree. I 
have a DH11 MUX on my PDP-11/34 and it improved the terminal-handling 
performance of RSTS/E geometrically.


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