Talk:PDP-11

message: The stuff about orthogonal addressing modes is not completely correct. I think the writer is confusing with the VAX which was (almost?) completely orthogonal. The PDP-11 was not. Most instructions were two address, with one operand (usually the source) allowing all addressing modes, but the other operand had to be a register. The MOV instruction allowed all modes for both operands. There were also some single operand instructions, some no-operand instructions, and a few weirdos that didn't fit the pattern. In all, it was a cleaner than a monstrosity like Intel 8088, but you couldn't call it completely orthogonal. (I don't think i ever wrote any PDP-11 assembler, but i recently translated some into ANSI C. I've also done minor tweaks to an emulator.)
:I'm sorry, but you're incorrect. With exception of the floating point stuff and the fact that ADD and SUB must be word-oriented (and not byte-oriented), all of the two-operand PDP-11 opcodes are orthogonal, taking the general form of:
::(Byte_Flag) (3-bit_opcode) (6-bit_Source_Specifier) (6-bit_Destination_Specifier)
:And both specifiers took precisely the same form:
::(3-bit_Mode) (3-bit_Register_Selector)
:The supported opcodes were:
:* x1 MOV
:* x2 CMP
:* x3 BIT
:* x4 BIC
:* x5 BIS
:* 06 ADD (only on 16-bit word)
:* 16 SUB (only on 16-bit word)
:The (rather limited) Floating Instruction Set, by comparison, implements a stack-oriented machine that always has one of its operands on the R6 stack. And the Floating Point Processor instruction set is, as you say, non-orthogonal, generally having one operand specified by generalized specifier and one operand that must be in a Floating Register. But please realize that both of these were options to the basic PDP-11 instruction set and were designed to fit into the rather-small opcode space allowed by the 16-bit wordlength. (As mentioned in the Orthogonal instruction set article, a fully-orthogonal instruction set isn't very bit-efficient.)
:Atlant 13:48, 22 Mar 2005 (UTC)
replies: text: Things get somewhat less orthogonal with the opcodes added later on, like MUL and XOR; those take a register plus a general operand. Paul Koning 20:00, 17 March 2007 (UTC)

text: No, it could be applied to either operand.  Guy Harris 01:34, 16 March 2006 (UTC)

text: Not just either, but both operands.  Constructs such as MOV 2(R2),4(R3) were entirely valid, and would assemble (in octal) as 016263; 000002; 000004 Xarqi 11:53, 2 October 2007 (UTC)
replies: text:  FIS has both operands on a stack, and delivers the result on the same stack. The register operand just denotes which register holds the stack pointer. There is a different instruction set extension EIS, which is implemented in all processors since the 11/40, which fits the above description of non-orthogonality. EIS contains fixed point multiplication and divison, and arithmetic shift. The register operand of MUL and DIV instructions is a set of 2 registers, if the register is an even numbered one. --Glasreiniger 08:12, 16 March 2006 (UTC)
thread_title: Instruction set orthogonality

message: PDP-11 was flagged as needing attention because "this needs to be more easily understood".
Though it is a bit dry, I had no trouble understanding the article. Its terms appear to be well-defined. 
What parts must be more easily understood??
[207.112.115.248]
----
If you are an assembly language programmer, it is perfectly clear.  But
most folks are not.
I think PDP-11 needs two more sections:
* On the social significance of the machine.  Who used it?  What did they do with it?  What new feats did it enable?  What was its market niche?
* Why did DEC build it?  (The article almost answers this.)  Why did they drop it?  Is it associated with struggles within DEC?  Did it make money for DEC?  (Those of us who were fondly dependent on one or more DEC machines are deeply interested in this sort of thing.)
[207.172.11.147]
----
The section "Decline of the PDP-11" asserts a design deficiency that eventually made the model uncompetitive.  The second, parenthesized, paragraph gives details of a programming project (too detailed for this location, I think) for the purpose of providing a counterexample.  I'm too new here to delete someone else's contribution, but the solution seems to be for the statement in the first paragraph to be less categorical.  --Spike, Brentwood NH
—Preceding unsigned comment added by 24.60.78.79 (talk) 15:33, 18 October 2008 (UTC)
thread_title: Cleanup?

message: I am aware that the PDP-11 had the following types of applications in the 1980's:
*Academic institutions used them to train scientists and engineers in computer programming.  The PDP-11 had a great little Fortran compiler and could service multiple terminals in a computer lab.
*They got used as remote communications processors to control printers etc. connected to mainframe computers.
*Siemens used duplicated-redundant PDP-11's to operate their telex exchanges.
I suspect that they also got a lot of use in industry as numerical machine or industrial process controllers.  Basically the PC became more powerful and cheaper for the single user and industrial applications and the VAX was the natural upgrade path before computer servers came along. kiwiinapanic 10:19 Jan 20, 2003 (UTC)
: That's a tiny fraction of the applications.  Here are some more:
* General timesharing (e.g., RSTS/E, IAS
* Process control systems
* Embedded controllers
* Turnkey applications (e.g., Typeset-11)
* Commercial data processing systems (CTS-300, CTS-500)
and so on. Paul Koning 20:00, 17 March 2007 (UTC)
thread_title: PDP-11 application areas

message: The article contains the following text:
:Finally, the PDP-11 was designed to be produced in a factory by semiskilled labor. All of the dimensions of its pieces were relatively noncritical. All parts of the computer chassis were constructed from injection-molded plastic, or bent steel rod (lighter than sheet metal). It used a push-bonded backplane. That is, the printed circuit board plugged into a backplane connector. The backplane connector had terminals that could be connected by pushing wires into them. The terminal would cut the insulation around the wire and bite into the wire to for a gas-tight (i.e. corrosion-proof, therefore reliable) connection. The connector blocks were very similar to telephone connection blocks. The case was injection-molded plastic that snapped over the steel-rod chassis.
Does anyone have any idea what that paragraph is trying to talk about? It clearly contains a few things that are true; some '11s did use a bent-wire frame, many '11s used automatic wire-wrapping for some portion of their backplane wiring, etc., but the paragraph as a whole seems to have a fairly loose grip on reality, and certainly doesn't reflect the original PDP-11 implementation.
If no one chimes in, I'll eventually take a crack at cleaning it up, but the whole topic will be somewhat lengthy as a number of radically different packaging technologies were used by the various PDP-11 models.
Atlant 17:15, 8 Feb 2005 (UTC)
thread_title: Physical packaging

message: Can anyone verify that Digital sold UNIX for the PDP-11? I'm tempted to move UNIX to the third-party section.
--Rochkind 8 July 2005 04:41 (UTC)
:I don't think Digital resold Unix directly, but Unix was absolutely available for the PDP-11; this was Thompson and Ritchie's second platform after the PDP-7. (See the picture at the top of this article!) DEC's "Telco" product Line (TPG) was essentially devoted to the Unix business. By the time of Ultrix on the VAX, Digital was directly reselling Unix.
:Atlant 8 July 2005 12:49 (UTC)
::To put it more precisely: At the time of Ultrix-32 they also sold Ultrix-11 for the PDP-11. Ultrix-11 was essentially BSD-2.9 IIRC. See PUPS archive at http://minnie.tuhs.org/PUPS/ --Glasreiniger 07:29, 11 July 2005 (UTC)
replies: text: Yes, but that wasn't purchased from DEC; you got that from another part of Bell Labs.  This section is discussing the UNIX sold by DEC for the PDP-11, i.e. Ultrix-11. Guy Harris (talk) 18:51, 28 December 2018 (UTC)
thread_title:  Digital sold UNIX for the PDP-11? 

message: I started collecting information about historical computers and creating related articles. So I stumbled upon Iskra Delta 800, which is said to be PDP-11/34 compatible with some extensions, developed by Iskra Delta but using actual J11.
Iskra Delta was a company from Yugoslavia, which was not behind the "iron curtain". I do not recall making completely unlicensed clones (like behind the curtain), although it is quite possible that using original components one would make a compatible computer (the components themselves were not copied). Peripheral devices were often not produced at all and originals were used. Read about that just a tad bit more in History of computer hardware in the SFRY.
Does anyone have more information on this or can provide some guidance? My searches for PDP 11 "compatibles" yielded no results other than Iskra Delta 800 - was it really the only official non-clandestine one?
--Aleksandar Šušnjar 15:21, 14 April 2006 (UTC)
replies: text: As far as I know Digital never licensed the PDP-11 to anyone, so all clones are clandestine. Paul Koning 20:00, 17 March 2007 (UTC)
thread_title: Iskra Delta 800: Clandestine clone or not?

message: That statement is true for a few of the early models, like the 11/20.  It is not true for the later, higher performance, models, starting with the 11/45 and much more obviously so for the 11/70.  In the 11/70 there are two I/O buses (Unibus and Massbus), plus a memory bus.
That said, it is true for all of them that there are no dedicated I/O instructions and the I/O devices are memory-mapped.  The same is true in many other processor architectures, whether they have a unified bus or not. Paul Koning 20:00, 17 March 2007 (UTC)
thread_title:  "No dedicated I/O bus" is inaccurate 

message: Per previous editors comments I'm removied the following section from the article. I'd love to know if any of these stories are true, but they need verification to be in the article.--agr 15:28, 8 July 2007 (UTC)
replies: text: The computer system in the METROL metropolitan train control centre in Melbourne, Australia is still in regular commercial service. This system runs an operating system coded in Swedish PASCAL for the creation of train timetables, fleet management and passenger information displays.  Several nuclear plants around the world, including Canada, the Netherlands and Sweden, still run PDP-11s.  Many research institutions still regularly run PDP-11s for data collection or instrumentation control.  Australia Post still use PDP-11/93's running RSX-11 on some of their older Optical Character Recognition machinery. Flight simulators (such as the 747 operated by MK Airlines) use a PDP-11. Computer Organization and Programming course at the Technion is still being taught using PDP-11 Assembly.
Some number of years ago, 2007 I think, the actual DEC PDP-11s were replaced with Strobe Data's (strobedata.com) Osprey Co-processor series, a PDP-11 "clone" authorized initially by none other than Ken Olsen himself. Metro currently uses approximately 20 Osprey/DX Co-processors, ISA, 2X PDP-11/93-94 instruction throughput, Legacy Unibus I/O supported.
Metro now considering upgrading to Osprey/Qxp ("p" for PCI), 4X instruction execution rate of PDP-11/93-94.
TFL, Transport For London, currently considering upgrading to the very same Co-processor HARDWARE, reconfigured, Kestrel/Qxp (FPGA, WCS) for replacing HP-1000 mini-computer, A600, etc. Wwest40 (talk) 18:06, 18 January 2013 (UTC)
thread_title:  PDP-11s still in service? 

message: I have fond memories of the PDP-11.  As a consequence of the architecture, the instruction set contained as a valid instruction, "MOV -(PC),-(PC)".  When encountered, this instruction propagated itself backwards through the machine's memory, all the way to Address 0.  Sometimes, this complicated debugging, since the offending code could be wiped out.  On the other hand, it made a handy memory diagnostic.  You toggled an "012727" into the highest location in memory, and hit "Run".  If there was a serious memory failure, you could find it by toggling in various addresses to examine, and seeing how far down the "012727's" had propagated.
Alan Hochberg 19:17, 12 July 2007 (UTC)
replies: text: It's 014747, but apart from that, yes indeed, that was a neat trick. Paul Koning 21:44, 5 September 2007 (UTC)
thread_title:  PDP-11 Self-Propagating Instruction 

message: I just reverted a merge with MACRO-11 for two reasons: (1) I think merges should be proposed first, (2) in this particular case, merging a programming language with a hardware article isn't necessarily a good idea.
Admittedly the MACRO-11 article is short, but that could be cured by expanding it.
Paul Koning (talk) 23:02, 17 February 2008 (UTC)
replies: text: My main concern with the MACRO-11 article is that it is not notable enough to carry its own article; it has no application or context outside of its use in PDP-11 systems, especially since both are defunct and only of historical interest. The alternative that I will pursue is deletion. I also don't see how or why PDP-11 should be a hardware article. First, it already contains an assembly programming section which I expanded to merge the MACRO-11 content. Secondly, the PDP-11 refers to a system, not exclusively the hardware, which would be a different article, PDP-11 hardware. To put it another way, a discussion of TiVo includes both the hardware and software -- and there is no separate article to discuss its software. If MACRO-11 were independent of the PDP-11, I would agree that it would warrant its own article; as it is, however, MACRO-11 is merely a sub-topic of the PDP-11, and as you admit, it doesn't contain enough content to justify a split on organizational grounds. Ham Pastrami (talk) 00:08, 18 February 2008 (UTC)

text: Ah, not to mention the list of operating systems, which is also not hardware. Ham Pastrami (talk) 00:11, 18 February 2008 (UTC)
replies: text:  I don't agree with the "notable" argument, especially since Macro-11 clearly serves as the template for many other assembly languages.  Apart from that, I still don't understand why that justifies skipping the normal process -- discuss first, act after there is time to see that there is consensus. Paul Koning (talk) 15:26, 18 February 2008 (UTC)
replies: text:  I also do not agree with the "notable argument"!--Tim32 (talk) 01:06, 8 May 2008 (UTC)
replies: text:  Me either. The Tivo analogy is wildly off point: Tivo is an appliance, inseparable from its built-in software. That's not the case with a general-purpose computer. Now if there was a separate article on the PDP-11 instruction set, I would agree that that material belongs here. But a macro assembly language is far, far more than a representation of the computer's instruction set. Jeh (talk) 07:25, 8 May 2008 (UTC)

text:  It really bugs me that the merge of "MACRO-11" was done again, even after I pointed out that there is a process to follow for this (which wasn't followed) and after there were several objections and no one speaking up in favor.  Why was this done? Paul Koning (talk) 21:28, 19 May 2008 (UTC)
replies: text:  I'd just like to comment that IMHO, the native assembly language of one of the most influential architectures in computer history should be notable enough for Wikipedia. Also, from experience of reading and editing similar articles, I would expect an article entitled "PDP-11" to focus mainly on the hardware, with in-depth descriptions of associated operating systems, assembly languages etc. to be delegated to other articles. Letdorf (talk) 09:48, 20 May 2008 (UTC)
replies: text:  So, revert the merge. The merge obviously flies in the face of consensus. It wouldn't hurt to flesh out the Macro-11 article with more information about directives, lexical operators, etc. Jeh (talk) 14:22, 21 May 2008 (UTC)
thread_title:  Macro-11 article 

message: This picture, while a very nicely done picture, suggests that the PDP-11 was stuck in the Stone Age. The picture of the old PDP-11 with DECtape drives doesn't help either. In fact, later models of the PDP-11 worked with a wide variety of MASSBUS peripherals including RP06 disk drives. Does anyone have some pictures of such? Jeh (talk) 01:02, 22 May 2008 (UTC)
replies: text: A picture of newer/larger peripherals, or perhaps a picture of a large 11/70 system, would certainly be nice.  Then again, the existing pictures are also appropriate, reflecting the first few years of the product line. Paul Koning (talk) 16:47, 21 August 2008 (UTC)
thread_title:  That paper tape picture 

message: The article says that DEC sold the PDP-11 in the 70s and 80s. I think that is slightly misleading. The last PDP-11 model from DEC, the PDP-11/93 and PDP-11/94 were introduced in 1990. Note that this was a new model. That would imply that they still had a fairly acceptable business into the 90s as well. /bqt (bqt@softjar.se)
--213.65.173.92 (talk) 12:43, 26 July 2008 (UTC)
replies: text: Maybe, but everyone was more focused on VAXes, SPARCstations, high end PCs, etc. by then.  Even though I was a PDP nut, I didn't pay any attention to the 90 series, and it was barely mentioned at DECus meetings.  —EncMstr (talk) 16:21, 26 July 2008 (UTC)
replies: text:  If reliable references can be supplied, I think this should be mentioned. Stating that DEC was selling the PDP-11 in the 70s and 80s when in fact sales continued through to the 90s makes the statement inaccurate. Rilak (talk) 06:57, 27 July 2008 (UTC)
replies: text:  Reliable references? The 11/93 and 11/94 was introduced in 1990 (anyone have any marketing material? Otherwise, how about the manuals for the new machines, dated 1990, and marked as new material, which are available at bitsavers?). What more do you need? I don't really know what kind of references are acceptable, and available. This is as close to a known fact as anything I can think of. What references do we have that the PDP-11 started selling in 1970? Anyway, DEC then sold the (almost) whole PDP-11 software business to Mentec in 1994. In 1998 DEC made available firmware upgrades for the 11/93 and 11/94 to cope with a Y2K issue (I have the upgrade on my systems, and it have a copyright notice saying 1998). Mentec continued to sell new PDP-11 systems will into the 21st century. In fact, there is still atleast one company making new PDP-11 processors. /bqt (bqt@softjar.se) 212.112.174.86 (talk) 08:54, 20 August 2008 (UTC)
replies: text:  I was not questioning the truthfulness of your edits, I'm just saying that any statement or claim needs to be referenced (it is standard Wikipedia policy). Go ahead, edit the article to make it more complete. I have found a reliable reference here:  (bottom of page) quote: "May 1990: The 20th anniversary of the first PDP-11 computer is marked by the introduction of two new PDP-11 systems: the MicroPDP-11/93 and the PDP-11/94." Rilak (talk) 11:45, 20 August 2008 (UTC)

text:  :) I didn't think you were questioning the truthfulness as such. I just asked about the need for references. After all, the original claim of the PDP-11 being sold in the 70s and 80s didn't have any references either. It's just that it feels like the need for references sometimes seems excessive. And especially when it comes to some information while other information that appears to be on the same level are provided without references. Where should the line be drawn? It feels a little arbitrary, and perhaps wrong at times. /bqt (bqt@softjar.se) --212.112.174.86 (talk) 17:44, 23 September 2008 (UTC)
replies: text:  The reason why I said it needs references when adding such facts is more important as most editors will find that a computer sold in the 70s and 80s was still around in the 90s to be highly dubious, and therefore there is a risk it will be removed. Adding references stops that from happening. Rilak (talk) 08:56, 24 September 2008 (UTC)

text:  Who makes new PDP-11 processors?  There are lots of people in the classic computer crowd who'd like to know.  We've been trying to contact Mentec about PDP-11 things to no avail.  Frotz (talk) 01:35, 21 August 2008 (UTC)
replies: text:  I don't know how much "advertisement" is okay. But right now, the last manufacturer of PDP-11 processors that you can stick in your old backplane are Quickware (that I know of). And then of course you also have different levels of emulation, from Strobe who makes some hardware to pure software implementations. (bqt@softjar.se) --212.112.174.86 (talk) 17:44, 23 September 2008 (UTC)
thread_title:  Time span 

message: Following the example of the article on the Atmel AVR, I have split off former Section 5, Architectural details, into a separate article PDP-11 architecture.  This section was about half of the total PDP-11 article, which had gotten big, and would be of exclusive interest to techies, while the remaining text is of interest to persons studying the PDP-11 as a phenomenon.
The only changes I've made during this pass is that I didn't think the various optional instruction-set packages deserved separate mention in the Table of Contents; they are all now in Section 3.7, Optional instruction sets.  I've changed capitalization in some of the section heads to be more like Wikipedia, and created links between the two articles.  For now, I won't delete any of the See Alsos; other editors who know the works pointed to may decide they belong in one article and not the other. --Spike-from-NH (talk) 00:16, 15 February 2009 (UTC)
replies: text: In fact, there has been no comment at all, so the section on MACRO-11 is now moved.  --Spike-from-NH (talk) 22:04, 27 August 2009 (UTC)
thread_title:  Splitting off architectural details 

message: The term "common" doesn't appear to fit, since multiple-megabytes for a minicomputer were arguably rare in the late 1970s when the VAX was introduced. Suggest that the comment be toned down to reflect that Tedickey (talk) 21:00, 25 August 2009 (UTC)
replies: text: A comparable assertion (which doesn't assert that megabytes were "common") is made in the first paragraph of Section 3, "The Decline of the PDP-11." A separate problem with the sentence in the intro is that it asserts a fatal problem with the PDP-11, but instead of explaining it, directs the reader through the link "64k barrier" to the 16-bit article, which nowhere explains the problem or the "barrier," or relates 64k to 16-bit addressing except at the end,in examples involving the Intel architecture.  I recommend you simply delete the sentence.  --Spike-from-NH (talk) 04:12, 27 August 2009 (UTC)
thread_title:  Memory-size timeframe 

message: This article should be reorganized to be inclusive of ALL PDP-11s, then separated by bus implementation, Unibus and Q-Bus implementation differences. As currently organized, it almost suggests the Q-Bus systems were not PDP-11s. In fact, the 11/83 & 11/84 used the identical CPU board and private memory interconnect.
Ggdr
Gerry G 16:13, 16 July 2011 (UTC)
replies: text: Not sure what your specific proposal is. It seems to be mentioning the Q-Bus systems already? In fact, there is a whole section on the LSI-11. My question is if "LSI-11" was an official product name, an internal project name, or the name of the chip etc. I would say it is a bit odd to have the lists of models in the middle of the article. Would this work better in, say, a table? or just a simpler list, and more prose to give a narrative version? I would be interested in the years each one was announced or delivered, for example, as well as how they technically related. And of course any sources you can dig up would be greatly appreciated, thanks. W Nowicki (talk) 18:58, 16 July 2011 (UTC)
thread_title: Reorganization

message: Hello fellow Wikipedians,
I have just added archive links to  on PDP-11. Please take a moment to review my edit. If necessary, add  after the link to keep me from modifying it. Alternatively, you can add  to keep me off the page altogether. I made the following changes:
*Added archive https://web.archive.org/20100209023553/http://www.patersontech.com:80/Dos/Micronews/paterson04_10_98.htm to http://www.patersontech.com/Dos/Micronews/paterson04_10_98.htm
*Added archive https://web.archive.org/20110718232453/http://www.classiccmp.org/pipermail/cctech/2006-February/057197.html to http://www.classiccmp.org/pipermail/cctech/2006-February/057197.html
When you have finished reviewing my changes, please set the checked parameter below to true to let others know.
Cheers. —cyberbot IITalk to my owner:Online 10:48, 27 August 2015 (UTC)
thread_title:  External links modified 

message: TRAX is listed under "third party operating systems". It was not; it was implemented by DEC, on the RSX11M (or possibly M+, I forget!) kernel.  — Preceding unsigned comment added by 173.76.121.238 (talk) 02:26, 21 October 2019 (UTC)
replies: text: Yup. Guy Harris (talk) 06:53, 21 October 2019 (UTC)
thread_title: TRAX: a DEC operating system

message: I've just undone this deleted entry as it is not an advertisement and it is relevant to improving this article. This whole entry was deleted without an answer to the question which still stands. I'll restate this as: Would it be appropriate to document the PiDP-11 and may be other systems that are being implemented in hardware?
What is given below is an indication that there have been significant sales i.e. over 1,000 and the hardware is still on back order. Then I documented in this talk page that there were other PDP-11 systems implemented in hardware. The first was a CPU module that can be inserted into DEC's Unibus backplanes. 
Next hardware implementations of PDP-11 systems were based on Field Programmable Gate Arrays (FPGAs). This is a similar concept to the VAX-11/750 CPU except these days technology has advanced to the point where the whole CPU can be contained in one device. It is probably impossible to estimate how many PDP-11 systems based on VHDL have been implemented.
The text below would not be added to the article in this current form. It would definitely need to be edited with an axe. I have no relationship with any of these makers except that I have a PiDP-11 on order. My background included hardware maintenance of PDP-11 and VAX systems, plus using these systems as home PCs (insert photo of VAX-11/750 on seagrass matting). Hence my interest in hardware implementations. It may be appropriate for somebody with knowledge of VHDL and FPGAs to review the references to determine the relevance of these PDP-11 systems implemented in silicon.
I deliberately raised these topics on the Talk Page to isolate the text extracted from maker's web sites. I have an email from the maker of the PiDP-11 kit stating that to date he has supplied just over 1,000 of these systems. Demand for these systems is so high that they are still on back order e.g. I was sitting at the end of the order queue in October 2018, was too late with my March 2019 order confirmation, and I should receive my PiDP-11 in the next batch, probably in April 2019. This was only included here to show there were significant sales and this section may not be included on the article page.
https://obsolescence.wixsite.com/obsolescence/pidp-11<ref>
I have very poor Wiki editing skills so it may be appropriate for somebody else to expand the article page.
 
The PiPDP-11 has been reviewed in a magazine article.
<ref>https://www.raspberrypi.org/magpi/pidp-11-review/  
Buried in the PiPD-11 web site are references to other implementations of PDP-11 systems in hardware. The production volumes of these PDP-11 implementations is unknown.        `
             
The makers web site links to Unibone a Linux to UNIBUS bridge.
http://retrocmp.com/projects/unibone
The makers web site links to PDP2011 which is PDP-11 systems implemented in VHDL on FPGA boards.
http://pdp2011.sytse.net/wordpress/pdp-11/ The PDP2011 web site stated: ″The VHDL of the PDP11 core is not vendor specific. I regularly use both Xilinx and Altera FPGA’s, and the VHDL works unchanged on both."
While the PDP2011 Overview states:
"This website describes PDP2011 – a re-creation of the well known series of PDP-11 computer systems in VHDL. Everything that is needed to run a PDP-11 system is included; you can run a complete Unibus PDP-11 system with console, disks and other peripherals on a simple low cost FPGA development board. The original V5-V7 versions of Unix, BSD 2.11, and the original DEC operating systems for the PDP-11 work. 
Current status
The CPU model is configurable, from the smallest 11/10 up to the biggest 11/70 and J-11 systems. Model-specific exceptions are implemented to the point that many of the original XXDP MAINDEC test programs run without error, and the original model detection code used by the operating systems in most cases correctly identifies the configured model.
The memory management unit handles 18- or 22 bit translation and supports separate instruction and data spaces, as well as kernel, supervisor and user mode. For the 11/45 and 11/70, the 3-bit ACF is implemented including memory management traps and A- and W-bits; all other models have the later, simpler version of memory management based on a 2-bit ACF. The special maintenance mode is implemented – this makes it possible to run the original XXDP test programs to verify that the MMU works correctly. For the 22-bit processor models the Unibus map is included in the memory management unit.
Model-specific optional instructions, like SPL, MARK, MxPx, MxPS, MFPT, CSM etc. are present according to the CPU model.
J-11, 11/45 and 11/70 have the dual general purpose register set.
The EIS instructions: MUL, DIV, ASH, ASHC, and XOR are available if the CPU model supports them.
The floating point processor is complete, and is included by default with the CPU models that it could optionally be installed in. It can be disabled too, to save FPGA resources.
RK11 and RL11 disk controllers work and use SD cards to store the disk data on. Up to 8 RK05 or 4 RL02 disks can be emulated on a single SD card.
If the RK or RL disks are too small, then there is the option to configure a RH70 (for 11/70) or RH11 controller with a single RP04, RM05, or RP06 disk. The disk data for the RM or RP disk is also stored on a SD card.
A KW11L line clock is present; by default it is configured at 60Hz, but 50Hz and 400Hz are also possible.
Up to four serial lines for console and terminals can be configured.
A DEUNA/DELUA compatible core is available; the DEUNA core is a front end for a ENC424J600 ethernet chip, which does most of the ‘real’ ethernet work. Digilent’s PMODNIC100 contains the ENC424J600 chip, and can be easily connected to FPGA boards.
If the FPGA board includes ps2 and vga ports, a simple terminal can be added to the FPGA core so you don’t need a pc with hyperterm or minicom to run a PDP-11. The CPU that runs the software for the terminal is of course also a PDP-11.
Everything is verified in hardware, on both Altera and Xilinx boards. The VHDL is not vendor specific, so it should be possible to make it work on any FPGA that is large enough with only minor changes in the top level VHDL to map the board resources like connectors, blinkenlights and memories to the core. Several top level VHDL files and tool chain project definitions are available for popular development boards from Terasic and Digilent.
Oscar Vermeulen’s PiDP-11 console can be connected to the FPGA. At present this is still somewhat experimental and requires lots of wiring, but the logic works, and we’re developing a PCB to hook up the FPGA board to the console.
A DR11C can be configured; this is one of the simplest versions of a ‘universal peripheral’ that allows interaction between the cpu and a ‘user device’."
:The description of the PiPDP-11 isn't relevant.  Text extracted from maker's Web sites belongs on the maker's Web sites; you can just link to that site rather than just copying and pasting a big block of stuff.
:"The text below" isn't going to be added to PDP-11 at all; it simply doesn't belong there.  The PDP-11 page doesn't go into that level of detail for real PDP-11's; if the PiDP-11 is worthy of more than a mention in the Emulators section, or another section at the end, that would belong in a "PiDP-11" page.
:The "Emulators" section describes software simulators.
:The PiDP-11 is a combination of one of those simulators (SIMH) running on a Raspberry Pi with a reimplementation of the front panel; it sounds as if the peripherals are simulated.  I'm not sure whether they're suggesting that the Unibone card could be used to provide a real UNIBUS for a simulated PDP-11 or not.  A case can be made that the PiDP-11 might deserve to be an item in a separate section, as there's more to it than just the simulator.
:The PDP2011 is a PDP-11 implemented in FPGA, so I think it would definitely belong in a separate section at the end.
:But, again, there's no reason to give all those details on the PDP-11 page; if either the PiDP-11 or the PDP2011 is notable, in the Wikipedia sense, they should be given their own page, with relevant details mentioned. Guy Harris (talk) 03:31, 22 March 2019 (UTC)
replies: text: I agree, this is a very interesting and relevant development, and perhaps deserves its own Wikipedia article, with a cross-ref from this one. Until/unless such an article exists, it is appropriate to discuss it here. Reify-tech (talk) 15:56, 22 March 2019 (UTC)
replies: text: This might not yet be notable, but it is worth discussing on this talk. There would need to be a lot more notable coverage to create a separate article. I would be inclined to rename the emulator section here to something more generic like legacy. I notice that the article does not mention that the VAX-11 had a hardware assisted PDP-11 compatibility mode. Then the emulators text. Perhaps add a single sentenace that there are ongoing attempts to simulate the 11 with a link to The Register article. I wouldn't mention the company or the product by name. I don't see any notable mentions of the FPGA projects, but there is some recent academic interest in a PDP-11 on a chip. There's an interesting reference to an 11 simulator being used to teach machine-level programming. I wouldn't consider any one of these projects to be WP notable itself, but there have been/are numerous efforts to replicate the 11. --mikeu talk 16:46, 22 March 2019 (UTC)
thread_title: PiDP-11: RECREATING THE PDP-11/70 (Second Attempt)

message: * http://hampage.hu/tpa/e_tpa1140.html is a reference
* http://hampage.hu/pdp-11/links.html has references
:Oko5ekmi5 (talk) 07:24, 26 September 2020 (UTC)
thread_title:  hampage.hu 

message: === DEC Datasystem 350 ===
All DEC Datasystem 350 models have PDP-11/10 CPUs.
=== DEC Datasystem with PDP-11/34 ===
PDP-11/34 decdatasystem.   (talk) 11:10, 4 November 2022 (UTC)
thread_title:  DEC Datasystem 

message: PDP-11/34 decdatasystem.   (talk) 11:10, 4 November 2022 (UTC)
thread_title:  DEC Datasystem with PDP-11/34