[TUHS] What's with the DZ-11?

[TUHS] What's with the DZ-11?

[Noel Chiappa]

    > From: Ronald Natalie

    >> each single DZ hex board supported 8 lines (fully independent of any
    >> other cards); the full DH replacement did need two boards, though.

    > Eh? The DH/DM from Able was a single hex board and it supported 16
    > lines.

To be read in the context of Clem's post which I was replying to: to replace
the line capacity of a DH (16 lines), one needed two DZ cards.

	Noel

[TUHS] What's with the DZ-11?

[Noel Chiappa]

    > From: Dave Horsfall <dave at horsfall.org>

    > a 9-track tape followed me home, but even if I knew where it was now it
    > ain't gonna be readable after over 30 years...

Umm, don't be too sure!

I have several sets of backup tapes from one of the V6 machines at MIT, and
those are also roughly 30 years old, and they are not in the best shape (they
sat in my basement for most of that time). I sent one off to someone who
specializes in reading old tapes, and he's gotten almost all the bits off of
it (a few records had unrecoverable read errors, but the vast majority were
OK - like roughly 15 read errors in around 1500 records).

So do look for that tape (unless the material is all already online).

I hope to annouce a vast trove of stuff soon from my tapes (once I figure out
how to interpret the bits - they are written by a sui generis application
called 'saveRVD', and the _only_ documentation of how it did it is... on that
tape! :-) That includes a lot of code written at MIT, as well as stuff
from elsewhere.

Coming sbould be BCPL, Algol, LISP and some other languages; MACRO-11 and the
DEC linker (which I guess are also available from UNSW tapes),but _also_
programs to convert back and forth from .REL to a.out format, and to .LDA
format; and a whole ton of other applications (I have no idea what all is
there - if anyone is interested, I can make a pass through my manuals and try
and make a list).

	Noel

[TUHS] What's with the DZ-11?

[Warner Losh]

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> On Dec 1, 2014, at 5:32 AM, Noel Chiappa <jnc at mercury.lcs.mit.edu> wrote:
> Coming sbould be BCPL, Algol, LISP and some other languages; MACRO-11 and the
> DEC linker (which I guess are also available from UNSW tapes),but _also_
> programs to convert back and forth from .REL to a.out format, and to .LDA
> format; and a whole ton of other applications (I have no idea what all is
> there - if anyone is interested, I can make a pass through my manuals and try
> and make a list).

I remember playing ZORK (dungeo) in college on a VAX 11/750 which was
a PDP-11 a.out run in emulation mode (well, to be honest it was even more
complex than that, since there was a shell script to open all the data files on
specific FDs, setup some weird environment variables and then the PDP-11
program was run). The image looked to be converted from an RT-11 version
of the program that I ran under RSTS/E on a PDP-11/34 while working for a
small database company in high school…

I’d always wondered how that came to be, and what tools were needed to
run it...

Warner

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[TUHS] What's with the DZ-11?

[Clem Cole]

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On Mon, Dec 1, 2014 at 10:46 AM, Warner Losh <imp at bsdimp.com> wrote:

> I remember playing ZORK (dungeo) in college on a VAX 11/750 which was
> a PDP-11 a.out run in emulation mode (well, to be honest it was even more
> complex than that, since there was a shell script to open all the data
> files on
> specific FDs, setup some weird environment variables and then the PDP-11
> program was run). The image looked to be converted from an RT-11 version
> of the program that I ran under RSTS/E on a PDP-11/34 while working for a
> small database company in high school…
>
> I’d always wondered how that came to be, and what tools were needed to
> run it...
>
Ah the "dmap" talk from the guys at Pitt in I think the winter 1980 USENIX
conference.

The story is that it was indeed an RT11 image.  The guys at Pitt hacked up
"enough" support for the 11 emulation mode on 4.1 to allow it to run.   The
project was referred to as "dmap manipulation" to keep it under the radar.
I can picture the face of the guy that did it, but I've forgotten his name.
  I fear it was early enough in USENIX time that there might not be
proceedings.

Clem
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[TUHS] What's with the DZ-11?

[Noel Chiappa]

    > From: Clem Cole <clemc at ccc.com>

    > two issues. first DEC subsetted the modem control lines so running
    > modems - particularly when you wanted hardware flow control like the
    > trailblazers - did not work.

?? We ran dialup modems on our DZ11s (1200 bps Vadics, IIRC) with no problems,
so you must be speaking only some sort of high-speed application where you
needed the hardware flow control, or something, when you say "running modems
... did not work".

Although, well, since the board didn't produce an interrupt when a modem
status line (e.g. 'carrier detect') changed state, we did have to do a kludge
where we polled the device to catch such modem control line changes. Maybe
that's what you were thinking of?

    > To Dave the DZ was great because it was two boards to do what he
    > thought was the same thing as a DH

To prevent giving an incorrect impression to those who 'were not there', each
single DZ hex board supported 8 lines (fully independent of any other cards);
the full DH replacement did need two boards, though.

	Noel

[TUHS] What's with the DZ-11?

[Ronald Natalie]

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The original Trailblazers were special modems that on a good like could approach 19.2KB.   T  They also had special software that recognized when UUCP protocol stuff was being transfer and apportion the bandwidth and spoof the ACKS on the protocol to increase the UUCP throughput.

Believe me, running a bunch of 9600 data transfers on a DZ will pretty much saturate the unibus in a hurry.  The thing didn’t even have the ability to operate at 19.2.
The statement is correct.   The DZ doesn’t support or even make programatically the CTS/RTS lines and as you did indicate, the RI/CD didn’t generate interrupts and had to be polled.

[TUHS] What's with the DZ-11?

[Ronald Natalie]

> 
> To prevent giving an incorrect impression to those who 'were not there', each
> single DZ hex board supported 8 lines (fully independent of any other cards);
> the full DH replacement did need two boards, though.
> 
Eh?  The DH/DM from Able was a single hex board and it supported 16 lines.

[TUHS] What's with the DZ-11?

[Dave Horsfall]

On Thu, 27 Nov 2014, Noel Chiappa wrote:

> To prevent giving an incorrect impression to those who 'were not there', 
> each single DZ hex board supported 8 lines (fully independent of any 
> other cards); the full DH replacement did need two boards, though.

And was really really expensive, which is why we had DJ-11s instead, hence 
our rapture on the coming of the DZ-11.

Oh, and I'm a software person, with a good knowledge of hardware (I was 
forever trying to tell the hardware bods that it was their problem and not 
mine, and I practically had to rub their noses in it).

DEC used to fob us off because we ran Unix; it was only when DECEX became 
available that the overlapped-seeks issue on the RK-11 was finally 
acknowledged, as RSX/RSTS didn't use that feature, and MAINDEC didn't prod 
it.

-- 
Dave Horsfall DTM (VK2KFU)  "Bliss is a MacBook with a FreeBSD server."
http://www.horsfall.org/spam.html (and check the home page whilst you're there)

[TUHS] What's with the DZ-11?

[Ronald Natalie]

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> 
> DEC used to fob us off because we ran Unix; it was only when DECEX became 
> available that the overlapped-seeks issue on the RK-11 was finally 
> acknowledged, as RSX/RSTS didn't use that feature, and MAINDEC didn't prod 
> it.
> 
That was the story of my life running the UNIX machines, not only from DEC and other
service guys but also the manufacturers themselves.    Sometimes I had to bluff and
say i was experiencing the problem with the proprietary OS.     I had to remember not
to use our slang for the other OS’s (both HP’s MPX and Gould’s MPE we referred to
as Might Pour Excuse).

[TUHS] What's with the DZ-11?

[Noel Chiappa]

    > From: Dave Horsfall <dave at horsfall.org>

    > what was the problem with them?

Well, not a _problem_, really, but.... 'one interrupt per output character'
(and no way around that, really). So, quite a bit of overhead when you're
running a bunch of DZ lines, at high speeds (e.g. 9600 baud).

I dunno, maybe there was some hackery one could pull (e.g. only enabling
interrupts on _one_ line which was doing output, and on a TX interrupt,
checking all the other lines to see if any were i) ready to take another
character, and ii) had a character waiting to go), but still, it's still going
to be more CPU overhead than DMA (which is what the DH used).

	Noel

[TUHS] What's with the DZ-11?

[Dave Horsfall]

I've seen a couple of less than flattering references here; what was the 
problem with them?

At UNSW, we couldn't afford the DH-11, so ended up with the crappy DJ-11 
instead (the driver for the DH-11 had the guts ripped out of it in an 
all-nighter by Ian Johnston as I recall), and when the DZ-11 came along we 
thought it was the bees' knees.

Sure, the original driver was as slow as hell, but the aforesaid IanJ 
reworked it and made it faster by at least 10x; amongst other things, I 
think he did away with the character queues and used the buffer pool 
instead, getting 9600 on all eight channels simultaneously, possibly even 
full-duplex.

-- 
Dave Horsfall DTM (VK2KFU)  "Bliss is a MacBook with a FreeBSD server."
http://www.horsfall.org/spam.html (and check the home page whilst you're there)

[TUHS] What's with the DZ-11?

[Ronald Natalie]

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The DZ was always looked down upon in my shops.   The problem is that it interrupts the processor on every output character which isn’t particularly efficient.   We used the DH-11 and as previously mentioned when able came out with the single board DH/DM-11 clone, we used those.

I also had some goofy board (DQ) that allowed you to load a character table on when you wanted interrupts on input (you could program it for new line and whatever your INTR/QUIT/ERASE/KILL, etc… were) but I never got around to writing the driver for that.

[TUHS] What's with the DZ-11?

[Clem Cole]

two issues.    first DEC subsetted the modem control lines so running modems - particularly when you wanted hardware flow control like the trailblazers - did not work. 

second as others pointed out there the buffering was mostly lacking and the interrupt load was terrible on the OS



if DEC had used different and better USARTs this would not have been as bad.  When it came out there were other options for the HW guys but IMO it was an example of tunnel vision - plus HW guys not really understanding the SW implications of the choice.  

one of the guys behind the DZ would later become a good friend of mine.  I realized Dave never looked at RS-232 the same way SW people did.   To Dave the DZ was great because it was two boards to do what he thought was the same thing as a DH - ie cheaper / less power / smaller etc. But the saving was a HW one and not what we needed.  


that said DEC sold a lot of them on VMS systems.  it was us UNIX guys that switched to Able's board as soon as we could.  Cheaper and better functionality for the OS.  

ken once told me he always loved us Unix guys because we got it.  he also listened too us and built what we needed when he could.  I tried to get him to put the DH/DM on a AT form factor but he said he could not make money at it.  Eventually the rocket port guys built and ASIC and pretty much did it

Clem 


> On Nov 26, 2014, at 3:48 PM, Dave Horsfall <dave at horsfall.org> wrote:
> 
> I've seen a couple of less than flattering references here; what was the 
> problem with them?
> 
> At UNSW, we couldn't afford the DH-11, so ended up with the crappy DJ-11 
> instead (the driver for the DH-11 had the guts ripped out of it in an 
> all-nighter by Ian Johnston as I recall), and when the DZ-11 came along we 
> thought it was the bees' knees.
> 
> Sure, the original driver was as slow as hell, but the aforesaid IanJ 
> reworked it and made it faster by at least 10x; amongst other things, I 
> think he did away with the character queues and used the buffer pool 
> instead, getting 9600 on all eight channels simultaneously, possibly even 
> full-duplex.
> 
> -- 
> Dave Horsfall DTM (VK2KFU)  "Bliss is a MacBook with a FreeBSD server."
> http://www.horsfall.org/spam.html (and check the home page whilst you're there)
> _______________________________________________
> TUHS mailing list
> TUHS at minnie.tuhs.org
> https://minnie.tuhs.org/mailman/listinfo/tuhs

[TUHS] What's with the DZ-11?

[Dave Horsfall]

On Thu, 27 Nov 2014, Dave Horsfall wrote:

> I've seen a couple of less than flattering references here; what was the 
> problem with them?

A number of responses, all of which boil down to the same thing, viz: an 
interrupt on each character.

I know that, which is why we (UNSW) re-worked the driver; I can't believe 
that we were the only ones who did so.  It cleaned out as many silos as it 
could, possibly even by disabling interrupts completely and using clock 
ticks; I can't remember.

With any luck, the driver (dz.c?) should be on Minnie somewhere; it was 
done by Ian Johnston(sp?) at the Australian Graduate School of Management
(ianj at agsm, or possibly ianj at agsm70).

-- 
Dave Horsfall DTM (VK2KFU)  "Bliss is a MacBook with a FreeBSD server."
http://www.horsfall.org/spam.html (and check the home page whilst you're there)

[TUHS] What's with the DZ-11?

[Larry McVoy]

On Fri, Nov 28, 2014 at 06:45:38AM +1100, Dave Horsfall wrote:
> On Thu, 27 Nov 2014, Dave Horsfall wrote:
> 
> > I've seen a couple of less than flattering references here; what was the 
> > problem with them?
> 
> A number of responses, all of which boil down to the same thing, viz: an 
> interrupt on each character.
> 
> I know that, which is why we (UNSW) re-worked the driver; I can't believe 
> that we were the only ones who did so.  It cleaned out as many silos as it 
> could, possibly even by disabling interrupts completely and using clock 
> ticks; I can't remember.

This problem is old as the hills, at SGI we did similar stuff for networking
cards.  We could run something like 8 HIPPI cards at full bandwidth with
some 200mhz MIPS cpus.  Lots of work in the networking stack to go get the
next packet if it was there after we did this one.

[TUHS] What's with the DZ-11?

[Warren Toomey]

On Fri, Nov 28, 2014 at 06:45:38AM +1100, Dave Horsfall wrote:
> With any luck, the driver (dz.c?) should be on Minnie somewhere; it was 
> done by Ian Johnston(sp?) at the Australian Graduate School of Management
> (ianj at agsm, or possibly ianj at agsm70).

Is this is?

http://minnie.tuhs.org/cgi-bin/utree.pl?file=AUSAM/sys/dmr/dz.c

Cheers, Warren

[TUHS] What's with the DZ-11?

[Dave Horsfall]

On Sun, 30 Nov 2014, Warren Toomey wrote:

> > With any luck, the driver (dz.c?) should be on Minnie somewhere; it 
> > was done by Ian Johnston(sp?) at the Australian Graduate School of 
> > Management (ianj at agsm, or possibly ianj at agsm70).
> 
> Is this is?
> 
> http://minnie.tuhs.org/cgi-bin/utree.pl?file=AUSAM/sys/dmr/dz.c

That's the one!  Bless you :-)

It'll take a while to work through it again, and I can see that I was 
wrong about the use of the buffer pool (our printer drivers certainly used 
them, along with the Calcomp and the Versatec). but I can see that it does 
funky things otherwise.

-- 
Dave Horsfall DTM (VK2KFU)  "Bliss is a MacBook with a FreeBSD server."
http://www.horsfall.org/spam.html (and check the home page whilst you're there)

[TUHS] What's with the DZ-11?

[Warren Toomey]

On Sun, Nov 30, 2014 at 05:43:05PM +1100, Dave Horsfall wrote:
> > http://minnie.tuhs.org/cgi-bin/utree.pl?file=AUSAM/sys/dmr/dz.c
> That's the one!  Bless you :-)

There seems to be an earlier one here at
http://minnie.tuhs.org/cgi-bin/utree.pl?file=AUSAM/sys/dmr/dz.c-elec

Cheers, Warren

[TUHS] What's with the DZ-11?

[Dave Horsfall]

On Sun, 30 Nov 2014, Warren Toomey wrote:

> > > http://minnie.tuhs.org/cgi-bin/utree.pl?file=AUSAM/sys/dmr/dz.c
> > That's the one!  Bless you :-)
> 
> There seems to be an earlier one here at
> http://minnie.tuhs.org/cgi-bin/utree.pl?file=AUSAM/sys/dmr/dz.c-elec

Hadn't realised that there were two different *fast* versions, but I do 
recall using the KW-11P gave blazing performance.  Well, when you had the 
11/70 loaded with *seven* DZ-11s, something had to be done...

Warren, would the old CSU40/CSU60 stuff be around?  I pretty much ran that 
place until I left; a 9-track tape followed me home, but even if I knew 
where it was now it ain't gonna be readable after over 30 years...

If I could figure out how to search by file name, I'd look for, oh, "ei.c" 
(the UT200 driver that I wrote), "lv.c" (Versatec LV-11 driver), and 
"xy.c" (which would be the Calcomp plotter).

-- 
Dave Horsfall DTM (VK2KFU)  "Bliss is a MacBook with a FreeBSD server."
http://www.horsfall.org/spam.html (and check the home page whilst you're there)