This article is about the PDP–11 series of minicomputers. For the PDP–11 processor architecture, seePDP-11 architecture.
ThePDP–11is a series of16-bitminicomputerssold byDigital Equipment Corporation(DEC) from 1970 into the late 1990s, one of a set of products in theProgrammed Data Processor(PDP) series. In total, around 600,000 PDP-11s of all models were sold, making it one of DEC's most successful product lines. The PDP-11 is considered by some experts to be the most popular minicomputer.[1][2]
PDP–11
A PDP–11/40 CPU is at the bottom, with a TU56 dualDECtapedrive installed above it.
The PDP–11 included a number of innovative features in itsinstruction setand additional general-purposeregistersthat made it easier to program than earlier models in the PDP series. Further, the innovativeUnibussystem allowed external devices to be more easily interfaced to the system usingdirect memory access,opening the system to a wide variety ofperipherals.The PDP–11 replaced thePDP–8in manyreal-time computingapplications, although both product lines lived in parallel for more than 10 years. The ease of programming of the PDP–11 made it popular for general-purpose computing.
The design of the PDP–11 inspired the design of late-1970smicroprocessorsincluding theIntelx86[1]and theMotorola 68000.The design features of PDP–11 operating systems, and other operating systems from Digital Equipment, influenced the design of operating systems such asCP/Mand hence alsoMS-DOS.The first officially named version ofUnixran on the PDP–11/20 in 1970. It is commonly stated that theC programming languagetook advantage of several low-level PDP–11–dependent programming features,[3]albeit not originally by design.[4]
An effort to expand the PDP–11 from 16- to 32-bit addressing led to theVAX-11design, which took part of its name from the PDP–11.
In 1963, DEC introduced what is considered to be the first commercial minicomputer in the form of thePDP–5.This was a 12-bit design adapted from the 1962LINCmachine that was intended to be used in a lab setting. DEC slightly simplified the LINC system and instruction set, aiming the PDP-5 at smaller settings that did not need the power of their larger 18-bitPDP-4.The PDP-5 was a success, ultimately selling about 1,000 machines. This led to thePDP–8,a further cost-reduced 12-bit model that sold about 50,000 units.
During this period, the computer market was moving fromcomputer wordlengths based on units of 6 bits to units of 8 bits, following the introduction of the 7-bitASCIIstandard. In 1967–1968, DEC engineers designed a 16-bit machine, the PDP–X,[5]but management ultimately canceled the project as it did not appear to offer a significant advantage over their existing 12- and 18-bit platforms.
This prompted several of the engineers from the PDP-X program to leave DEC and formData General.The next year they introduced the 16-bitData General Nova.[6]The Nova sold tens of thousands of units and launched what would become one of DEC's major competitors through the 1970s and 1980s.
Ken Olsen,president and founder of DEC, was more interested in a small 8-bit machine than the larger 16-bit system. This became the "Desk Calculator" project. Not long after,Datamationpublished a note about adesk calculatorbeing developed at DEC, which caused concern atWang Laboratories,who were heavily invested in that market. Before long, it became clear that the entire market was moving to 16-bit, and the Desk Calculator began a 16-bit design as well.[7]
The team decided that the best approach to a new architecture would be to minimize the memory bandwidth needed to execute the instructions. Larry McGowan coded a series ofassembly languageprograms using the instruction sets of various existing platforms and examined how much memory would be exchanged to execute them. Harold McFarland joined the effort and had already written a very complex instruction set that the team rejected, but a second one was simpler and would ultimately form the basis for the PDP–11.[7]
When they first presented the new architecture, the managers were dismayed. It lacked single instruction-word immediate data and short addresses, both of which were considered essential to improving memory performance. McGowan and McFarland were eventually able to convince them that the system would work as expected, and suddenly "the Desk Calculator project got hot".[7]Much of the system was developed using aPDP-10where the SIM-11 simulated what would become the PDP–11/20 and Bob Bowers wrote an assembler for it.[7]
At a late stage, the marketing team wanted to ship the system with 2K of memory[a]as the minimal configuration. When McGowan stated this would mean an assembler could not run on the system, the minimum was expanded to 4K. The marketing team also wanted to use the forward slash character for comments in the assembler code, as was the case in the PDP–8 assembler. McGowan stated that he would then have to use semicolon to indicate division, and the idea was dropped.[7]
The PDP–11 family was announced in January 1970 and shipments began early that year. DEC sold over 170,000 PDP–11s in the 1970s.[8]
The PDP–11 processor architecture has a mostlyorthogonal instruction set.For example, instead of instructions such asloadandstore,the PDP–11 has amoveinstruction for which either operand (source and destination) can be memory or register. There are no specificinputoroutputinstructions; the PDP–11 usesmemory-mapped I/Oand so the samemoveinstruction is used; orthogonality even enables moving data directly from an input device to an output device. More complex instructions such asaddlikewise can have memory, register, input, or output as source or destination.
Most operands can apply any of eight addressing modes to eight registers. The addressing modes provide register, immediate, absolute, relative, deferred (indirect), and indexed addressing, and can specify autoincrementation and autodecrementation of a register by one (byte instructions) or two (word instructions). Use of relative addressing lets a machine-language program beposition-independent.
Early models of the PDP–11 had no dedicatedbusforinput/output,but only asystem buscalled theUnibus,as input and output devices were mapped to memory addresses.
An input/output device determined the memory addresses to which it would respond, and specified its owninterrupt vectorandinterrupt priority.This flexible framework provided by the processor architecture made it unusually easy to invent new bus devices, including devices to control hardware that had not been contemplated when the processor was originally designed. DEC openly published the basic Unibus specifications, even offering prototyping bus interface circuit boards, and encouraging customers to develop their own Unibus-compatible hardware.
A PDP–11/70 system that included two nine-track tape drives, two disk drives, a high speed line printer, a DECwriter dot-matrix keyboard printing terminal and a cathode ray tube terminal installed in a climate-controlled machine room
The Unibus made the PDP–11 suitable for custom peripherals. One of the predecessors ofAlcatel-Lucent,theBell Telephone Manufacturing Company,developed the BTMC DPS-1500 packet-switching (X.25) network and used PDP–11s in the regional and national network management system, with the Unibus directly connected to the DPS-1500 hardware.
Higher-performance members of the PDP–11 family departed from the single-bus approach. The PDP–11/45 had a dedicated data path within theCPU,connecting semiconductor memory to the processor, with core memory and I/O devices connected via the Unibus.[10]In the PDP–11/70, this was taken a step further, with the addition of a dedicated interface between disks and tapes and memory, via theMassbus.Although input/output devices continued to be mapped into memory addresses, some additional programming was necessary to set up the added bus interfaces.
The PDP–11 supports hardwareinterruptsat four priority levels. Interrupts are serviced by software service routines, which could specify whether they themselves could be interrupted (achieving interruptnesting). The event that causes the interrupt is indicated by the device itself, as it informs the processor of the address of its own interrupt vector.
Interrupt vectors are blocks of two 16-bit words in low kernel address space (which normally corresponded to low physical memory) between 0 and 776. The first word of the interrupt vector contains the address of the interrupt service routine and the second word the value to be loaded into the PSW (priority level) on entry to the service routine.
The PDP–11 was designed for ease of manufacture by semiskilled labor. The dimensions of its pieces were relatively non-critical. It used awire-wrappedbackplane.
The LSI–11 (PDP–11/03), introduced in February 1975[9]is the first PDP–11 model produced usinglarge-scale integration;the entire CPU is contained on four LSI chips made byWestern Digital(theMCP-1600chip set; a fifth chip can be added to extend the instruction set). It uses a bus which is a close variant of the Unibus called the LSI Bus orQ-Bus;it differs from the Unibus primarily in that addresses and data are multiplexed onto a shared set of wires rather than having separate sets of wires. It also differs slightly in how it addresses I/O devices and it eventually allowed a 22-bit physical address (whereas the Unibus only allows an 18-bit physical address) and block-mode operations for significantly improved bandwidth (which the Unibus does not support).
The CPUmicrocodeincludes adebugger:firmware with a direct serial interface (RS-232orcurrent loop) to aterminal.This lets the operator dodebuggingby typing commands and readingoctalnumbers, rather than operating switches and reading lights, the typical debugging method at the time. The operator can thus examine and modify the computer's registers, memory, and input/output devices, diagnosing and perhaps correcting failures in software and peripherals (unless a failure disables the microcode itself). The operator can also specify which disk tobootfrom. Both innovations increased the reliability and decreased the cost of the LSI-11.
AWritable Control Store(WCS) option (KUV11-AA) could be added to the LSI-11. This option allowed programming of the internal 8-bit micromachine to create application-specific extensions to the PDP–11 instruction set. The WCS is a quad Q-Bus board with a ribbon cable connecting to the third microcode ROM socket. The source code for EIS/FIS microcode was included so these instructions, normally located in the third MICROM, could be loaded in the WCS, if desired.[11]
Later Q-Bus based systems such as the LSI–11/23, /73, and /83 are based upon chip sets designed in house by Digital Equipment Corporation. Later PDP–11 Unibus systems were designed to use similar Q-Bus processor cards, using a Unibus adapter to support existing Unibusperipherals,sometimes with a special memory bus for improved speed.
There were other significant innovations in the Q-Bus lineup. For example, a system variant of the PDP–11/03 introduced full systempower-on self-test(POST).
The basic design of the PDP–11 was flexible, and was continually updated to use newer technologies. However, the limitedthroughputof the Unibus andQ-Busstarted to become a system-performancebottleneck,and the 16-bit logical address limitation hampered the development of larger software applications. The article onPDP–11 architecturedescribes the hardware and software techniques used to work around address-space limitations.
DEC's 32-bit successor to the PDP–11, theVAX–11(for "Virtual Address eXtension" ) overcame the 16-bit limitation, but was initially asuperminicomputeraimed at the high-endtime-sharingmarket. The early VAX CPUs provided a PDP–11compatibility modeunder which much existing software could be immediately used, in parallel with newer 32-bit software, but this capability was dropped with the firstMicroVAX.
For a decade, the PDP–11 was the smallest system that could runUnix,[12]but in the 1980s, theIBM PCand its clones largely took over the small computer market;BYTEin 1984 reported that the PC'sIntel 8088microprocessor could outperform the PDP–11/23 when running Unix.[13]Newer microprocessors such as theMotorola 68000(1979) andIntel 80386(1985) also included 32-bit logical addressing. The 68000 in particular facilitated the emergence of a market of increasingly powerful scientific and technicalworkstationsthat would often run Unix variants. These included theHP 9000series 200 (starting with the HP 9826A in 1981) and 300/400, with theHP-UXsystem being ported to the 68000 in 1984;Sun Microsystemsworkstations runningSunOS,starting with theSun-1in 1982;Apollo/Domainworkstations starting with the DN100 in 1981 runningDomain/OS,which was proprietary but offered a degree of Unix compatibility; and theSilicon GraphicsIRISrange, which developed into Unix-based workstations by 1985 (IRIS 2000).
Personal computers based on the 68000 such as theApple LisaandMacintosh,theAtari ST,and theCommodore Amigaarguably constituted less of a threat to DEC's business, although technically these systems could also run Unix derivatives. In the early years, in particular,Microsoft'sXenixwas ported to systems like theTRS-80 Model 16(with up to 1 MB of memory) in 1983, and to the Apple Lisa, with up to 2 MB of installed RAM, in 1984. The mass-production of those chips eliminated any cost advantage for the 16-bit PDP–11. A line of personal computers based on the PDP–11, theDEC Professionalseries, failed commercially, along with other non-PDP–11 PC offerings from DEC.
In 1994, DEC[14]sold the PDP–11 system-software rights to Mentec Inc., an Irish producer of LSI-11 based boards for Q-Bus and ISA architecture personal computers, and in 1997 discontinued PDP–11 production. For several years, Mentec produced new PDP–11 processors. Other companies found aniche marketfor replacements for legacy PDP–11 processors, disk subsystems, etc. At the same time, free implementations of Unix for the PC based onBSDorLinuxbecame available.
By the late 1990s, not only DEC but most of the New England computer industry which had been built around minicomputers similar to the PDP–11 collapsed in the face of microcomputer-based workstations and servers.
The PDP–11 processors tend to fall into several natural groups depending on the original design upon which they are based and which I/Obusthey use. Within each group, most models were offered in two versions, one intended forOEMsand one intended for end-users. Although all models share the same instruction set, later models added new instructions and interpreted certain instructions slightly differently. As the architecture evolved, there were also variations in handling of some processor status and control registers.
Original PDP–11/20 front panelOriginal PDP–11/70 front panelLater PDP–11/70 with disks and tape
The following models use theUnibusas their principal bus:
PDP–11/20 and PDP–11/15 – 1970.[15]The 11/20 sold for $11,800.[16]The original, non-microprogrammed processor was designed by Jim O'Loughlin.Floating pointis supported byperipheraloptions using various data formats. The 11/20 lacks any kind ofmemory protectionhardware unless retrofitted with a KS-11memory mappingadd-on.[17]There was also a very stripped-down 11/20 at first called the 11/10,[citation needed]but this number was later re-used for a different model.
PDP–11/45 (1972),[15]PDP–11/50 (1973),[18]and PDP–11/55 (1976)[15]– A much faster microprogrammed processor that can use up to 256KBof semiconductor memory instead of or in addition tocore memoryand support memory mapping and protection.[17]It was the first model to support an optional FP11 floating-pointcoprocessor,which established the format used in later models.
PDP–11/35 and PDP–11/40 – 1973.[15]Microprogrammedsuccessors to the PDP–11/20; the design team was led by Jim O'Loughlin.
PDP–11/05 and PDP–11/10 – 1972.[15]A cost-reduced successor to the PDP–11/20. DEC Datasystem 350 models from 1975 include the PDP–11/10.[19]
PDP–11/70 – 1975.[15]The 11/45 architecture expanded to allow 4MBof physical memory segregated onto a private memory bus, 2 KB of cache memory, and much faster I/O devices connected via the Massbus.
PDP–11/34 (1976[15]) and PDP–11/04 (1975[15]) – Cost-reduced follow-on products to the 11/35 and 11/05; the PDP–11/34 concept was created by Bob Armstrong. The 11/34 supports up to 256 kB of Unibus memory. The PDP–11/34a (1978)[15]supports a fast floating-point option, and the 11/34c (same year) supported acache memoryoption.
PDP–11/60 – 1977.[15]A PDP–11 with user-writable microcontrol store; this was designed by another team led by Jim O'Loughlin.
PDP–11/44 – 1979.[15]A replacement for the 11/45 and 11/70, introduced in 1980, that supports optional (though apparently always included) cache memory, optional FP-11 floating-point processor (one circuit board, using sixteenAMDAm2901bit slice processors), and optional commercial instruction set (CIS, two boards). It includes a sophisticated serial console interface and support for 4 MB of physical memory. The design team was managed by John Sofio. This was the last PDP–11 processor to be constructed using discretelogic gates;later models were all microprocessor-based. It was also the last PDP–11 system architecture created byDigital Equipment Corporation,later models were VLSI chip realizations of the existing system architectures.
PDP–11/24 – 1979.[15]First VLSI PDP–11 for Unibus, using the "Fonz-11" (F11) chip set with a Unibus adapter.
PDP–11/84 – 1985–1986.[15]Using the VLSI"Jaws-11"(J11) chip set with a Unibus adapter.
PDP–11/94 – 1990.[15]J11-based, faster than 11/84.
A PDP–11/03 with cover removed to show the CPU board, with memory board beneath (Two of the CPU chipset's four 40-pin packages have been removed, and the optionalFPUis also missing.)
The following models use theQ-Busas their principal bus:
PDP–11/03 (also known as the LSI-11/03) – The first PDP–11 implemented withlarge-scale integrationICs, this system uses a four-packageMCP-1600chipset from Western Digital and supports 60 KB of memory.
PDP-11/23– Second generation of LSI (F-11). Early units supported only 248 KB of memory.
PDP–11/23+/MicroPDP–11/23 – Improved 11/23 with more functions on the (larger) processor card. By mid-1982, the 11/23+ supported 4 MB of memory.[20]
MicroPDP–11/73– The third generation LSI-11, this system uses the faster "Jaws-11" (J-11) chip set and supports up to 4 MB of memory.
MicroPDP–11/53 – Slower 11/73 with on-board memory.
MicroPDP–11/83 – Faster 11/73 with PMI (private memory interconnect).
MicroPDP–11/93 – Faster 11/83; final DEC Q-Bus PDP–11 model.
KXJ11 – Q-Bus card (M7616) with PDP–11 based peripheral processor and DMA controller. Based on a J11 CPU equipped with 512 KB of RAM, 64 KB of ROM, and parallel and serial interfaces.
Mentec M100– Mentec redesign of the 11/93, with J-11 chipset at 19.66 MHz, four on-board serial ports, 1-4 MB of on-board memory, and optional FPU.
Mentec M11– Processor upgrade board; microcode implementation of PDP–11 instruction set by Mentec, using the TI 8832 ALU and TI 8818 microsequencer fromTexas Instruments.
Mentec M1 – Processor upgrade board; microcode implementation of PDP–11 instruction set by Mentec, usingAtmel0.35μmASIC.[21]
Quickware QED-993 – High performance PDP–11/93 processor upgrade board.
DECserver 500 and 550 LAT terminal servers DSRVS-BA using the KDJ11-SB chipset
The PDT-11/150 smart terminal system had two 8-inch floppy disc drives.
The PDT series were desktop systems marketed as "smart terminals". The /110 and /130 were housed in aVT100terminal enclosure. The /150 was housed in a table-top unit which included two 8-inch floppy drives, three asynchronous serial ports, one printer port, one modem port and one synchronous serial port and required an external terminal. All three employed the same chipset as used on the LSI-11/03 and LSI-11/2 in four "microm" s. There is an option which combines two of the microms into one dual carrier, freeing one socket for an EIS/FIS chip. The /150 in combination with aVT105terminal was also sold asMiniMINC,a budget version of theMINC-11.
VT100 terminal
PRO-325
PRO-350
PRO-380
TheDEC Professionalseries are desktop PCs intended to compete with IBM's earlier8088and80286based personal computers. The models are equipped with 51⁄4inch floppy disk drives and hard disks, except the 325 which has no hard disk. The original operating system was P/OS, which was essentiallyRSX-11M+ with a menu system on top. As the design was intended to avoid software exchange with existing PDP–11 models, the poor market response was unsurprising. TheRT-11operating system was eventually ported to the PRO series. A port of theRSTS/Eoperating system to the PRO series was also done internal to DEC, but it was not released. The PRO-325 and -350 units are based on the DCF-11 ( "Fonz" ) chipset, the same as found in the 11/23, 11/23+ and 11/24. The PRO-380 is based on the DCJ-11 ( "Jaws" ) chipset, the same as found in the 11/53,73,83 and others, though running only at 10 MHz because of limitations in the support chipset.
PDP–11/27 – A Jaws-11 implementation that would have used theVAXBI Busas its principal I/O bus.
PDP–11/68 – A follow-on to the PDP–11/60 that would have supported 4 MB of physical memory.
PDP–11/74 – A PDP–11/70 that was extended to contain multiprocessing features. Up to four processors could be interconnected, although the physical cable management became unwieldy. Another variation on the 11/74 contained both the multiprocessing features and the Commercial Instruction Set. A substantial number of prototype 11/74s (of various types) were built and at least two multiprocessor systems were sent to customers for beta testing, but no systems were ever officially sold. A four processor system was maintained by the RSX-11 operating system development team for testing and auniprocessorsystem served PDP–11 engineering for general purpose timesharing. The 11/74 was due to be introduced around the same time as the announcement of the new 32-bit product line and the first model: the VAX 11/780. The 11/74 was cancelled because of concern for its field maintainability,[22]though employees believed the real reason was that it outperformed the 11/780[23]and would inhibit its sales. In any case, DEC never entirely migrated its PDP–11 customer base to the VAX. The primary reason was not performance, but the PDP–11's superior real-time responsiveness.[citation needed]
VT20 – Terminal with PDP–11/05 with direct mapped character display for text editing and typesetting (predecessor of the VT71).
PDP–11/34 front panel which was a replacement for toggle switches in earlier PDP–11 computersVT71 – Terminal with LSI-11/03 and Q-Bus backplane with direct mapped character display for text editing and typesetting.
VT173 – A high-end editing terminal containing an 11/03, which loaded its editing software over a serial connection to a host minicomputer. Used in various publishing environments, it was also offered with DECset, Digital's VAX/VMS 3.x native mode OEM version of theDatalogicsPager automated batch composition engine. When VT173 inventory was exhausted in 1985, Digital discontinued DECset and transferred its customer agreements to Datalogics. (HP now uses the name HPDECsetfor a software development toolset product.)MINC-23 laboratory computer
MINC-11– Laboratory system based on 11/03 or 11/23;[25]when based on the 11/23, it was sold as a 'MINC-23', but many MINC-11 machines were field-upgraded with the 11/23 processor. Early versions of the MINC-specific software package would not run on the 11/23 processor because of subtle changes in the instruction set; MINC 1.2 is documented as compatible with the later processor.
ThisUnimationrobot arm controller used DEC LSI-11 series hardware.
TheUnimationrobot arm controllers used Q-Bus LSI-11/73 systems with a DEC M8192 / KDJ11-A processor board and two DEC DLV11-J (M8043) async serial interface boards.
SBC 11/21 (boardname KXT11) Falcon and Falcon Plus – single board computer on a Q-Bus card implementing the basic PDP–11 instruction set, based on T11 chipset containing 32 KB static RAM, two ROM sockets, three serial lines, 20 bit parallel I/O, three interval timers and a two-channel DMA controller. Up to 14 Falcons could be placed into one Q-Bus system.
KXJ11 Q-Bus card (M7616) with PDP–11 based peripheral processor and DMA controller. Based on a J11 CPU equipped with 512 KB RAM, 64 KB ROM and parallel and serial interfaces.
HSC high end CI disk controllers used backplane mounted J11 and F11 processor cards to run the CHRONIC operating system.[26]
VAX Console – TheDEC Professional SeriesPC-38N with a real-time interface (RTI) was used as the console for theVAX 8500 and 8550.The RTI has two serial line units: one connects to the VAX environmental monitoring module (EMM) and the other is a spare that could be used for data transfer. The RTI also has a programmable peripheral interface (PPI) consisting of three 8-bit ports for transferring data, address, and control signals between console and the VAX console interface.[27]
T-11is a microprocessor that implements the PDP-11 instruction set architecture. It was developed for embedded systems and was the first single-chip microprocessor developed by DEC. It was sold on the open market.[28]
The PDP–11 was sufficiently popular that many unlicensed PDP–11-compatible minicomputers and microcomputers were produced inEastern Bloccountries. Some were pin-compatible with the PDP–11 and could use its peripherals and system software. These include:
CalData – Made in US, ran all DEC OSes.[32]The CalData hardware was sufficiently DEC-compatible that CalData memory boards could be used in DEC PDP–11 systems.
CORAL series (made atICE FelixinBucharest) and the INDEPENDENT series (made at ITCTimișoara)[33]running theRSX-11Moperating system (inRomania). The CORAL series had several models: the CORAL 4001 was roughly equivalent to the PDP–11/04, the CORAL 4011 was a PDP 11/34 clone, while the CORAL 4030 was a PDP–11/44 clone.[34]These were used in state-owned companies and in public universities, originally operated withpunched cards,later through video terminals like the RomanianDAF-2020,to teach FORTRAN and Pascal, until replaced by IBM PC compatibles, starting in 1991.
Systime Computersmodels 1000, 3000, 5000 – OEM agreement for sales in the UK and Western Europe, but disputes originated over both intellectual property infringement and indirect sales to theEastern Bloc.[35][36]
OS/45was a proposed operating system for the PDP-11/45 capable of batch processing, real time and timesharing.[40]It was cancelled during development as its requirements led to a system which was too large for the intended hardware.[41]
The DECSA communications server was a communications platform developed by DEC based on a PDP–11/24, with the provision for user installable I/O cards including asynchronous and synchronous modules.[44]This product was used as one of the earliest commercial platforms upon which networking products could be built, including X.25 gateways,SNAgateways,routers,andterminal servers.
Ethernet adaptors, such as the DEQNAQ-Buscard, were also available.
Many of the earliest systems on theARPANETwere PDP–11's
The DEC TU109-track tapedrive was also offered on other DEC computer series.
A wide range of peripherals were available; some of them were also used in other DEC systems like thePDP–8orPDP–10.
The following are some of the more common PDP–11 peripherals.
The PDP–11 family of computers was used for many purposes. It was used as a standard minicomputer for general-purpose computing, such astimesharing,scientific, educational, medical, government or business computing. Another common application wasreal-timeprocess controlandfactory automation.
SomeOEMmodels were also frequently used asembedded systemsto control complex systems like traffic-light systems, medical systems,numerical controlledmachining,or for network management. An example of such use of PDP–11s was the management of the packet switched networkDatanet1. In the 1980s, the UK'sair traffic controlradar processing was conducted on a PDP 11/34 system known as PRDS – Processed Radar Display System at RAF West Drayton.[citation needed]The software for theTherac-25medicallinear particle acceleratoralso ran on a 32K PDP 11/23.[45]
In 2013, it was reported that PDP–11 programmers would be needed to control nuclear power plants through 2050.[46]
Another use was for storage of test programs forTeradyneATEequipment, in a system known as the TSD (Test System Director). As such, they were in use until their software was rendered inoperable by theYear 2000 problem.The US Navy used a PDP–11/34 to control its Multi-station Spatial Disorientation Device, a simulator used in pilot training, until 2007, when it was replaced by a PC-based emulator that could run the original PDP–11 software and interface with custom Unibus controller cards.[47]
Ersatz-11, a product of D Bit,[49]emulates the PDP–11 instruction set running under DOS, OS/2, Windows, Linux orbare metal(no OS). It can be used to run RSTS or other PDP–11 operating systems.
SimHis an emulator that compiles and runs on a number of platforms (includingLinux) and supports hardware emulation for the DEC PDP–1, PDP–8, PDP–10, PDP–11, VAX, AltairZ80, several IBM mainframes, and other minicomputers.
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Q-Bus board with LSI-11/2 CPU
DEC "Fonz-11" (F11) Chipset
DEC "Jaws-11" (J11) Chipset
