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 PDP-11 ? 
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Joined: Sat Aug 03, 2013 11:02 pm
Posts: 43
My first question is: What is the smallest pdp-11 system that was made.
Second Off: What is the chance, that I will be able to buy *any* pdp-11 system

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Tue Oct 15, 2013 12:04 pm

Joined: Wed Apr 24, 2013 9:40 pm
Posts: 205
Location: Huntsville, AL
There are a number of small PDP-11 systems. Unfortunately, most are powered from large power supplies. At the time of their design and manufacture, memory and logic technology was in its infancy and very expensive. This meant that most of these mini-computer required several hundred Watts to operate. This is typically well beyond the power level that a typical hobbyist will likely be capable of supplying. In addition, think of having an oven in your office. Getting rid of the heat put out by these small computers is a significant consideration.

One model comes to mind in the category that you are asking about: PDP 11/05. It was typically the smallest system that DEC sold in mid- to late-70s. It would typically be equipped with 8kB (4096 16-bit words) of memory, but it could be expanded to a total of 64kB.

I don't follow this market very much, but it is my understanding that there are a number of these units still in existence in one state or another. They are typically listed on eBay for sale. That is the marketplace you will most likely find such a computer.

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Michael A.


Tue Oct 15, 2013 1:03 pm

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1632
Power might be as low as 100W for a small PDP, and price around $2000. But in both cases you also need some peripherals...

I found a pdp-11 you can telnet into:
Code:
$ telnet rsx.pdp-11.org.ru
Trying 178.49.9.102...
Connected to rsx.pdp-11.org.ru.
Escape character is '^]'.

Welcome to PDP-11.ORG.RU!


HEL GUEST /

RSX-11M-PLUS V4.6   BL87    [1,54] System    CTAKAH
16-OCT-13 02:37    Logged on Terminal TT1:  as GST4

Good Morning

    *****************************************************************
    *                                                               *
    *                    Welcome to RSX-11M-PLUS                    *
    *                                                               *
    *                  Version 4.6  Base level 87                   *
    *                                                               *
    *****************************************************************
 
    Last interactive login on Friday, October 11, 2013  17:24:59 (RT0:)
 
$ @LB:[1,2]SYSLOGIN.CMD

    This is RSX.PDP-11.ORG.RU, node CTAKAH at HECnet.

    See http://pdp-11.org.ru/~form/ctakah.html for more information about
    this system.  See http://pdp-11.org.ru/hecnet.html for more information
    about HECnet.

    WARNING: Please do NOT use "PRINT" command to print file content -
    it prints the file on system line printer.  Use "TYPE" command instead.

$ @ <EOF>


Tue Oct 15, 2013 7:39 pm

Joined: Wed Apr 24, 2013 9:40 pm
Posts: 205
Location: Huntsville, AL
That's cool Ed. Thanks.

In the early 80s (1982-1986, to be exact) I worked on a PDP 11/24 with 4MB RAM, two RL02 removable HDDs, a TU80 9-track mag tape unit, and an Analogic AP400 array processor. It ran RSX 11/M+ just like the one whose telnet session is included in your post. I used it for modeling and simulation of control systems. We plugged the PDP 11/24's bus into the target HW using two DR11-W DMA units. Seeing that RSX 11/M+ notice brings back some memories of late night programming sessions.

One really cool thing about the RSX 11/M+ OS was that you had to build it from scratch. It took about 4 hours for the PDP 11/24 to build it from the sources for our particular setup. I really learned a lot from those exercises. I imagine building Linux from the sources is similar, but that process doesn't appeal to me as much today as it did then when I was much younger.

Another thing that I found has never really been duplicated as well was the generation and installation of the common libraries. I would build the Fortran IV and other common system elements and lock them in memory. They would then be memory resident, and all users and applications would link these tools without requiring that they be loaded from the disks or tapes. DLLs are today's solution, but they don't seem to me to be as efficiently used or as elegant a solution.

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Michael A.


Wed Oct 16, 2013 12:49 am

Joined: Tue Dec 31, 2013 2:01 am
Posts: 111
Location: Sacramento, CA, United States
James_Parsons wrote:
My first question is: What is the smallest pdp-11 system that was made.
Second Off: What is the chance, that I will be able to buy *any* pdp-11 system

The pdp-11 has one of the most beautiful instruction sets I've ever witnessed. If you are interested in owning some actual working hardware, maybe you could try searching for its software-compatible little brother, the LSI-11. I know that Heathkit made a hobbyist kit based on the LSI-11 around 30 years ago, and you might have some luck finding one for sale.

Mike


Tue Dec 31, 2013 2:55 am

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1632
It turns out the PDP I mentioned above with telnet access is actually an emulation - there is a real one but availability is on request. (There are also real alphaservers running openvms)

But here's a page about assembling your own from boards bought on ebay:
http://pdp-11.org.ru/~form/pdp11-83/


Tue Dec 31, 2013 9:58 am

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1632
There's a nice writeup here about the process of writing and debugging a PDP-11 model for FPGA:
http://www.heeltoe.com/download/pdp11/README.html

via classiccmp mail list


Tue Dec 31, 2013 10:10 am

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1632
Here's an in-browser PDP-11 emulation running V6 Unix: http://pdp11.aiju.de/
Be sure to read the linked FAQ, which links in turn to the programming notes and the man pages.
You'll find C, Fortran and Basic, an assembler, and also some games: blackjack, chess, tic-tac-toe, hunt the wumpus and a quiz.
Also it has 'dc' if you like huge-number calculations like 2^255-19=a large prime.
Oh, and 'ed' is the editor... good luck with that.
Cheers
Ed


Fri Jan 31, 2014 12:44 pm

Joined: Tue Dec 31, 2013 2:01 am
Posts: 111
Location: Sacramento, CA, United States
BigEd wrote:
Here's an in-browser PDP-11 emulation running V6 Unix: http://pdp11.aiju.de/
Be sure to read the linked FAQ, which links in turn to the programming notes and the man pages.

I instantly like that guy!

Quote:
... Oh, and 'ed' is the editor... good luck with that.

It's not much different than vi on VAX Ultrix-32 that I used in college. I think that I could manage with a bit of practice.

Good link, as usual, Ed. Thanks!

Mike

:wq!


Fri Jan 31, 2014 3:14 pm

Joined: Mon Jun 23, 2014 4:56 pm
Posts: 5
Location: Canada
The Heathkit H11 was based on the LSI-11 CPU (PDP-11/03) and I think it was one of the smallest PDP-11 based machines. It could run HT-11 (Heathkit's version of RT-11) or real DEC RT-11 and TSX+ (a 3rd party OS). I had heard of someone trying to run RSX-11 on one, but I'm not sure of the success of that project. You still see them one Bay from time to time.

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Bill


Mon Jun 23, 2014 5:16 pm
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