PDP-11/93 Console Pinout and model rev.

From: Jerome H. Fine <jhfinepw4z_at_compsys.to>
Date: Fri Apr 12 15:07:43 2002

>Doc wrote:

> > On Thu, 11 Apr 2002, Doc Shipley wrote:
> > Does anyone have the pinout for the db25 console port? Assuming that
> > the 25-pin bulkhead connector marked "Console" is a serial console port?
> Well, with some help from Emanuel and an old post by Douglas Gwyn, I
> figured out that the 11/93's console is a "standard" RS232 serial port.
> The bulkhead DIP switches were set such that the console port was
> disabled, which threw me for a while, and one of my DB25-MMJ adapters
> has died, which threw me off for a _long_ while, but I finally got a
> boot monitor, and then brought up the OS. RSX-11M+
> Drat. I was hoping for Windows 2000.

Jerome Fine replies:

Why would you want to run a "MODERN" operating system like
Windows 2000? After all, it has an up-time measured in decades
and is not susceptible to attack by a virus or a worm. In addition
it only uses a couple of hundred MBytes for the operating system
files. And finally, there are very few bugs. Not like that really
dumb operating system that DEC (oops - Compaq) has available
free to hobby users called VMS. I hear the VMS usually crashes
once a day and is easily attacked by software bugs since it has no
hardware protection like execute only and read only memory.

Of course you are not able to run VMS under an emulator. So
you must use real hardware under the hobby license and run on
a real VAX or real Alpha hardware.

By the way, can you tell me the location of those files which
helped? I have an M8981-AA which I hope to receive the
Qbus cab kit for eventually.

> Damn thing didn't come with ethernet, either.

But you can buy a DECnet license for so little for RSX-11M-PLUS
although an ethernet board might be available for free via a trade.

> > Also, I understand that a M8981-AA is a 2M board
> > and a -BA is a 4M > board. How do I find out which?
> Boot monitor says 4M, but I had already figured that out from the
> little barcode sticker on the BA23. It says "*11Z93-BA*"

And that extra 2 MBytes of memory was also extremely low
in price when DEC was still selling the 11/93 module. I seem
to remember that the 4 MByte board was ONLY about $ US 2000
more than the 2 MByte board.

Can anyone remember how much a 4 MByte 30 pin SIMM cost
when they were new? I have a few lying around to show to
my great-great-grandchildren. Some even use 4 MBit DRAM
although most are the less expensive type that use 16 MBit DRAM.

> So will this guy boot from Tim Shoppa's RT-11 CD?

NO! The RT-11 Freeware CD from Tim Shoppa does NOT
contain any RT-11 distributions. Sorry. Do you want me to
send you one? Which version of RT-11? Do you have a CDROM
drive on the real PDP-11 hardware that is able to read 512 byte

If you already have a file under Windows 98 that is able to boot
RT-11 under Ersatz-11, I have found that Nero Burning can copy
that file under the "Burn Image" option to the CD - including the
first 64 blocks which the ISO file structure ignores - or so I am
told. Now that is an extremely interesting thought. Since RT-11
only needs the first 8 blocks to set up a file structure, it might be
possible to write a DSK file under the ISO file structure that
could be used by Ersatz-11 via the command:
but also the command
if Ersatz-11 could ever manage to access those 64 blocks like
can do in the commercial version. Since I can look at those
64 blocks (actually 16 2048 byte sectors) under Nero Burning,
maybe there are special requests to Windows 98 that Ersatz-11
is not aware of that will allow access to the first 64 blocks of
the CD even with the MOUNT DU0: CDROMI:/RONLY

> Doc, who is thrilled beyond belief

Now that I can understand. Enjoy the 11/93. But don't expect the
hype from DEC to be valid as far as speed is concerned. Based
on just a few measurements I once made, the 11/93 CPU speed
seems to be about twice as fast as an 11/73. A MACRO-11
file took about this many seconds using VM: (all in memory):
11/73 11/83 11/93
 270 180 135

Sincerely yours,

Jerome Fine
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Received on Fri Apr 12 2002 - 15:07:43 BST

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