[HECnet] DDCMP over asynchronous emulated lines on simh 4.0

[Johnny Billquist]

On 2013-05-01 23:18, Clem Cole wrote:
below

On Wed, May 1, 2013 at 3:20 PM, Mark Pizzolato - Info Comm
<Mark at infocomm.com <mailto:Mark at infocomm.com>> wrote:

      I would work with the DZ device first.   It has been tested and had
      its modem related behaviors more solidly verified.



This line had me chuckling.   DZ were notorious for being lousy at
supporting modems because they lacked all a number of the needed RS-232
modem control lines.

Its one of the many reasons why the UNIX community in those days, used
to recommend using Able Computer's DH/DM solution.     Which was 16 serial
lines with full modem control on a single unibus board (and as described
previously used DMA and had character buffering),     The Able DH's
actually could run at faster speeds than the DEC one did.

Are you sure about Able? I can't remember seeing any such thing from them. Emulex did that, though. SC02 and various incarnations. It didn't have full modem control, but enough for the common use.
Speed was better than a real DH-11 for sure, as well as just taking one slot. Really good and reliable piece.

I never experienced any actual problems with DZ-11 though, but I totally detest the thing because of performance issues.
(I probably have more DZ-11 laying around than I ever will use. DEC must have been giving them away for free...)

	Johnny

-- 
Johnny Billquist                                   || "I'm on a bus
                                                                  ||   on a psychedelic trip
email: bqt at softjar.se                         ||   Reading murder books
pdp is alive!                                         ||   tryin' to stay hip" - B. Idol