[Simh] Now some DZ/terminal questions

[Johnny Billquist]

Clem...

On 2017-03-09 15:58, Clem Cole wrote:
> Warren,
>
> We can take this offline.   The quick answer is as far as simh is
> concerned leave everything as 8 bits.
> I'll show you how to make the rest work properly.  The logins will run 8
> bits also, but will run with parity enabled which BSD will handle just
> peachy.

As far as I remember, Unixes normally deal with this in the driver, but 
correct me if I'm wrong.

> Also, as I mentioned independently, I very much recommend not using DZs,
> but using DH's.   Most BSD UNIX boxes ran with Able DHDM's because there
> were both higher performant and cheaper than 2 DZ-11 (the cost of single
> Able unit got you 16 ports, compared to 8 from DEC, plus they worked
> better).  The DZ were originally developed by DEC as a cost reduced
> terminal interface to the original DH11 - which was a full system unit
> on the Unibus and the DM11 (modem control was an option).  So they took
> of a lot of space/power etc.
>
> Unfortunately the DZ were CPU hog's (see one of Bill Joy's notes circa
> 1979-80 - which I probably have somewhere) and sadly the DZ's did not
> support full modem control (which was always a SW nightmare).  I would
> later get to know some of the folks that made those choices from DEC's
> HW team (they originally screwed up the original MC-500 serial boards
> also but that's another story).
>
> Anyway, int he late 1970's Able's Ken O cloned/enhanced the DH and DM
> into a single hex board and since the UNIX community was often
> university folk, driven by cost (and the DHDM [Able's product] plus did
> flow control in HW) they were the gold standard for UUCP, particularly
> with Trailblazer et al.

Totally agree. The DZ11 was/is a horrible device. But it must have been 
dirt cheap, as they can still be found everywhere a Unibus exists, more 
or less. I don't know how many I have piled up.

CPU hog only starts to describe it. It interrupts on each character in 
or out, which makes it a really big burden on the CPU. Add that to the 
VAX, which wasn't exactly fast at dealing with interrupts in the first 
place, and you could more or less kill the machine with a few serial 
lines. (It was really bad on a PDP-11 as well.)

The DH11 was a much better device, doing DMA instead, but as you 
mention, it was large. Also, not supported on VAXen.
Able's DH11 clone was a really sweet device. Love it.

DEC came out with the DHU-11 later on, which was similar in many ways.

I never cared much for hardware flow control myself, but for those who 
did, the DZ11 was also a problem, as you say.

All in all, people should just avoid the DZ-11 whenever they have a chance.

	Johnny

>
>
> As I said, we can take this off line, and I'll help you.
>
> Clem
>
> On Thu, Mar 9, 2017 at 7:03 AM, Warren Toomey <wkt at tuhs.org
> <mailto:wkt at tuhs.org>> wrote:
>
>     Hi all, thanks for your help with my earlier questions.
>
>     I'd like to set up several vax780 instances and run uucp (over TCP)
>     between them using one or more of the simulated DZ lines. But I want to
>     use the remaining DZ lines for logins.
>
>     Is there a way to set some DZ lines into 8-bit mode but keep the
>     other DZ lines in 7-bit mode? Only the uucp lines need to be 8-bit,
>     the normal login lines can be 7-bit.
>
>     Is there a way to set bind some (but not all) DZ lines to localhost
>     port X,
>     and some (but not all) DZ lines to any address port Y (or X, doesn't
>     matter)?
>     I want to make the uucp DZ TCP ports visible on the Internet, but
>     set the
>     normal login ports visible only to localhost.
>
>     Many thanks, Warren
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-- 
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