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  • jackrubin's Avatar
    February 22nd, 2021, 12:29 PM
    Tom, If it gets to the point where the RK05F is being scrapped, I'd like to get a handful of the quick-turn fasteners that hold the sheet metal...
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  • PG31's Avatar
    February 20th, 2021, 02:07 AM
    PG31 replied to a thread Rainbow in DEC
    @Gary, how did you get on with the extra memory card and colour graphics option for the Rainbow?
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    February 19th, 2021, 02:00 PM
    PG31 replied to a thread Emulex CS21 in DEC
    Thanks bqt, I don't plan on using it for anything apart from an extra load on the PSU. It was the only Unibus card at a reasonable price. I'd much...
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  • PG31's Avatar
    February 19th, 2021, 03:22 AM
    PG31 started a thread Emulex CS21 in DEC
    Hi, I'm looking for jumper and switch configuration for an Emulex CS21 F. I'm looking at putting this in my 11/24 to add load to the PSU. From what I...
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    February 13th, 2021, 11:40 AM
    jackrubin replied to a thread Teletype to linux in DEC
    CuriousMarc did just that with his Model 15 (baudot) teletype; probably some useful information for the ASCII machines as well -...
    12 replies | 419 view(s)
  • PG31's Avatar
    February 10th, 2021, 01:55 AM
    PG31 replied to a thread Rainbow in DEC
    Sorry Gary, but its not a real hobby if it doesn't put you in the other halves bad books :p I'm always looking on ePay for DEC related items, at the...
    7 replies | 630 view(s)
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    February 10th, 2021, 01:51 AM
    PG31 replied to a thread DEC Vaxstation 3100/30 in DEC
    #28, Macnoob asks how to export the installed licenses. I have several disks with VMS on in a several VAX and some not installed. The disk will...
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About RSX11M+

Basic Information

About RSX11M+
Hi all...

I guess I should introduce myself as a retired R&D engineer who used, administered and serviced Digital PDP-11 machines in his working career. We used these to develop software for microprocessor based systems of various types, and for sale on PDP-11's as a VAR. [Value Added Reseller]

I've used too many PDPs to list, but it includes everything from a PDP-10 to PDP-11/70 and some VAX machines. Experience includes both UNIBUS and QBUS platforms.

My "Computer Museum" [as it's referred to by my friends] includes about 30 machines altogether, of which 10 or 15 are DEC. I am ashamed to say, none of these have been powered in the last 10 years.

This is about to change however, as I'm doing some of those "bucket list" projects I've been meaning to "get around to" for the last 20 years.


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July 28th, 2015 08:40 AM
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February 13th, 2011

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View RSX11M+'s Blog

Recent Entries

Review of "The MiniComputer in the Laboratory" Cooper

by RSX11M+ on June 20th, 2011 at 06:02 PM
Quote Originally Posted by RSX11M+ View Post
The MiniComputer in the Laboratory
            with examples using the PDP-11

Author: James W. Cooper

Publisher: John Wiley & Sons
ISBN: 0 471 01883-X
309 pages plus bibliography, appendices and index - 368 total

Cut to the chase
- of the books I've reviewed so far, this has one of the most concise, complete opcode views of the PDP-11 I've encountered. Not for it's thoroughness in covering the instruction set, but for imparting to the

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Review of "MINICOMPUTER SYSTEMS..." Eckhouse & Morris

by RSX11M+ on June 16th, 2011 at 05:45 PM
Quote Originally Posted by RSX11M+ View Post

Richard H. Eckhouse, Jr.
L Robert Morris

ISBN 0-13-583914-9
On the cover: Diagram of the "Antikythera Mechanism" [1][2][3] 
491 Pages including Appendices and Index
This book would have been very useful had it been known to me in my early PDP-11 career. Not for programming, but for it's appeal to me

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Ancient PDP-11 Progamming in Opcode Book Review

by RSX11M+ on June 13th, 2011 at 08:29 PM
Quote Originally Posted by RSX11M+ View Post
Ok, got my first pick of a decent PDP-11 book for you guys.


Prentice Hall
ISBN 0-13-541888-7
Hard cover 7x10
185 short pages plus Appendices and an Index.
The Pros:

This is targeted for programmers already experienced in high level languages, who may not have ever programmed in assembly or machine code before on any machine.

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DCT11-AA Microprocessor - MODE register bit 12 - TESTER / USER mode

by RSX11M+ on April 3rd, 2011 at 11:09 PM
The question of the purpose and action of bit 12, in the T-11's "MODE" register is not easy to answer from available information.

The only comments offered, come from a scant line or two in the T-11 User Guide EK-DCT11-UG

SECTION 4.2.4 - Tester or User Mode (MR<12>)

Tester mode is for Digital Equipment Corporation's use only. If mode register bit 12 is high, (MR<12>=1), user mode is selected.
Timing diagrams on page A-52 seem to

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Updated April 4th, 2011 at 12:46 AM by RSX11M+


Various Evaluation Module and Prototype Design Photos

by RSX11M+ on April 1st, 2011 at 01:11 AM
I thought it might be fun to put together an "album" of photos of original development boards and prototype designs in my collection. This is by no means complete, but I have to start somewhere and I'll add to it as I organize my stuff.

First is a Digital Equipment Corporation DCT11 Evaluation Module Kit.

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Updated May 4th, 2011 at 11:34 PM by RSX11M+ (Spelling corrections)