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115-573: Digital Equipment Corporation (DEC)'s PDP-10 , later marketed as the DECsystem-10 , is a mainframe computer family manufactured beginning in 1966 and discontinued in 1983. 1970s models and beyond were marketed under the DECsystem-10 name, especially as the TOPS-10 operating system became widely used. The PDP-10's architecture is almost identical to that of DEC's earlier PDP-6 , sharing

230-426: A 19-inch rack . The backplanes allowed 25 modules in a single 5-1/4 inch section of rack, and allowed the high densities needed to build a computer. The original laboratory and system module lines were offered in 500 kilocycle, 5 megacycle and 10 megacycle versions. In all cases, the supply voltages were -15 and +10 volts, with logic levels of -3 volts (passive pull-down) and 0 volts (active pull-up). DEC used

345-610: A VAX CPU was the VAX-11/780 , announced in October 1977, which DEC referred to as a superminicomputer . Although it was not the first 32-bit minicomputer, the VAX-11/780's combination of features, price, and marketing almost immediately propelled it to a leadership position in the market after it was released in 1978. VAX systems were so successful that in 1983, DEC canceled its Jupiter project , which had been intended to build

460-575: A consequence of the symmetric design of the instruction set, it contains several no-ops such as JUMP. For example, JUMPN A,LOC jumps to the address LOC if the contents of register A is non-zero. There are also conditional jumps based on the processor's condition register using the JRST instruction. On the KA10 and KI10, JRST is faster than JUMPA, so the standard unconditional jump is JRST. The conditional skip operations compare register and memory contents and skip

575-595: A control processor. The KS10 design was crippled to be a Model A even though most of the necessary data paths needed to support the Model B architecture are present. This was no doubt intended to segment the market , but it greatly shortened the KS10's product life. The KS system uses a similar boot procedure to the KL10. The 8080 control processor loads the microcode from an RM03, RM80, or RP06 disk or magnetic tape and then starts

690-460: A device number, and 10 through 12 the instruction opcode. In both formats, bits 13 through 35 are used to form the "effective address", E. Bits 18 through 35 contain a numerical constant address, Y. This address may be modified by adding the 18-bit value in a register, X, the register number indicated in bits 14 to 17. If these are set to zero, no indexing is used, meaning register 0 cannot be used for indexing. Bit 13, I, indicates indirection, meaning

805-415: A device set to level 0 will not stop the processor even if it does raise an interrupt. Each device channel has two memory locations associated with it, one at 40+2N and the other at 41+2N, where N is the channel number. Thus, channel 1 uses locations 42 and 43. When the interrupt is received and accepted, meaning no higher-priority interrupt is already running, the system stops at the next memory read part of

920-623: A fashion similar to the BLK commands. Only the right 18 bits are tested in CONSZ. A second use of the CONO instruction is to set the device's priority level for interrupt handling. There are three bits in the CONO instruction, 33 through 35, allowing the device to be set to level 0 through 7. Level 1 is the highest, meaning that if two devices raise an interrupt at the same time, the lowest-numbered device will begin processing. Level 0 means "no interrupts", so

1035-405: A maximum main memory capacity (both virtual and physical) of 256 kilowords (equivalent to 1152 kilobytes ); the minimum main memory required is 16 kilowords. As supplied by DEC, it did not include paging hardware; memory management consists of two sets of protection and relocation registers, called base and bounds registers. This allows each half of a user's address space to be limited to

1150-583: A new virtual memory system, and would also improve performance by processing twice as much data at a time. The system would, however, maintain compatibility with the PDP-11, by operating in a second mode that sent its 16-bit words into the 32-bit internals, while mapping the PDP-11's 16-bit memory space into the larger virtual 32-bit space. The result was the VAX architecture, where VAX stands for Virtual Address eXtension (from 16 to 32 bits). The first computer to use

1265-476: A new device to be added easily, generally only requiring plugging a hardware interface board into the backplane and possibly adding a jumper to the wire wrapped backplane, and then installing software that read and wrote to the mapped memory to control it. The relative ease of interfacing spawned a huge market of third party add-ons for the PDP-11, which made the machine even more useful. The combination of architectural innovations proved superior to competitors and

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1380-467: A profit at the end of its first year. The original Laboratory Modules were soon supplemented with the "Digital System Module " line, which were identical internally but packaged differently. The Systems Modules were designed with all of the connections at the back of the module using 22-pin Amphenol connectors, and were attached to each other by plugging them into a backplane that could be mounted in

1495-438: A selection of System Building Blocks to implement a small 12-bit machine, and attached it to a variety of analog-to-digital (A to D) input/output (I/O) devices that made it easy to interface with various analog lab equipment. The LINC proved to attract intense interest in the scientific community, and has since been referred to as the first real minicomputer , a machine that was small and inexpensive enough to be dedicated to

1610-485: A self-sustaining business, the company would be free to use them to develop a complete computer in their Phase II. The newly christened "Digital Equipment Corporation" received $ 70,000 from AR&D for a 70% share of the company, and began operations in a Civil War -era textile mill in Maynard, Massachusetts , where plenty of inexpensive manufacturing space was available. In early 1958, DEC shipped its first products,

1725-532: A semi-automated manufacturing process. Its cycle time is 1 μs and its add time 2.1 μs. In 1973, the KA10 was replaced by the KI10, which uses transistor–transistor logic (TTL) SSI . This was joined in 1975 by the higher-performance KL10 (later faster variants), which is built from emitter-coupled logic (ECL), microprogrammed , and has cache memory. The KL10's performance was about 1 megaflops using 36-bit floating point numbers on matrix row reduction. It

1840-511: A separate input/output processor for further performance gains. Over 400 PDP-15's were ordered in the first eight months of production, and production eventually amounted to 790 examples in 12 basic models. However, by this time other machines in DEC's lineup could fill the same niche at even lower price points, and the PDP-15 would be the last of the 18-bit series. In 1962, Lincoln Laboratory used

1955-531: A set section of main memory , designated by the base physical address and size. This allows the model of separate read-only shareable code segment (normally the high segment) and read-write data/ stack segment (normally the low segment) used by TOPS-10 and later adopted by Unix . Some KA10 machines, first at MIT, and later at Bolt, Beranek and Newman (BBN), were modified to add virtual memory and support for demand paging , and more physical memory. The KA10 weighs about 1,920 pounds (870 kg). The 10/50

2070-485: A single large mainframe case, with a hexagonal control panel containing switches and lights mounted to lie at table-top height at one end of the mainframe. Above the control panel was the system's standard input/output solution, a punched tape reader and writer. Most systems were purchased with two peripherals , the Type 30 vector graphics display, and a Soroban Engineering modified IBM Model B Electric typewriter that

2185-659: A single task even in a small lab. Seeing the success of the LINC, in 1963 DEC took the basic logic design but stripped away the extensive A to D systems to produce the PDP-5 . The new machine, the first outside the PDP-1 mould, was introduced at WESTCON on August 11, 1963. A 1964 ad expressed the main advantage of the PDP-5, "Now you can own the PDP-5 computer for what a core memory alone used to cost: $ 27,000". 116 PDP-5s were produced until

2300-467: A special format of indirect word to extract and store arbitrary-sized bit fields, possibly advancing a pointer to the next unit. The PDP-10 does not use memory-mapped devices , in contrast to the PDP-11 and later DEC machines. A separate set of instructions is used to move data to and from devices defined by a device number in the instruction. Bits 3 to 9 contain the device number, with the 7 bits allowing

2415-653: A successor to the PDP-10 mainframe, and instead focused on promoting the VAX as the single computer architecture for the company. Supporting the VAX's success was the VT52 , one of the most successful smart terminals . Building on earlier less successful models, the VT05 and VT50 , the VT52 was the first terminal that did everything one might want in a single inexpensive chassis. The VT52

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2530-469: A total of 128 devices. Instructions allow for the movement of data to and from devices in word-at-a-time (DATAO and DATAI) or block-at-a-time (BLKO, BLKI). In block mode, the value pointed to by E is a word in memory that is split in two, the right 18 bits indicate a starting address in memory where the data is located (or written into) and the left 18 bits are a counter. The block instructions increment both values every time they are called, thereby increasing

2645-440: A turn to use the stripped-down TX-0, while largely ignoring a faster IBM machine that was also available. The two decided that the draw of interactive computing was so strong that they felt there was a market for a small machine dedicated to this role, essentially a commercialized TX-0. They could sell this to users where the graphical output or real-time operation would be more important than outright performance. Additionally, as

2760-882: A user process a "high" and a "low" memory: addresses with a 0 top bit use one base register and those with a 1 use another. Each segment is contiguous. Later architectures have paged memory access, allowing non-contiguous address spaces. The CPU's general-purpose registers can also be addressed as memory locations 0–15. There are three main classes of general instructions: arithmetic, logical, and move; conditional jump; conditional skip (which may have side effects). There are also several smaller classes. The arithmetic, logical, and move operations include variants which operate immediate-to-register, memory-to-register, register-to-memory, register-and-memory-to-both or memory-to-memory. Since registers may be addressed as part of memory, register-to-register operations are also defined. (Not all variants are useful, though they are well-defined.) For example,

2875-451: Is 30 bits, divided into a 12-bit section number at the bottom of the left 18 bits and an 18-bit offset within that section in the right 18 bits. A register can contain either a "local index", with an 18-bit unsigned displacement or local address in the right 18 bits, or a "global index", with a 30-bit unsigned displacement or global address in the right 30 bits. An indirect word can either be a "local indirect word", with its uppermost bit set,

2990-677: Is most famous as the machine for which the Unix operating system was originally written. Unix ran only on DEC systems until the Interdata 8/32 . A more dramatic upgrade to the PDP-1 series was introduced in August 1966, the PDP-9 . The PDP-9 was instruction-compatible with the PDP-4 and −7, but ran about twice as fast as the −7 and was intended to be used in larger deployments. At only $ 19,900 in 1968,

3105-522: Is no reason for any individual to have a computer in his home." Unsurprisingly, DEC did not put much effort into the microcomputer area in the early days of the market. In 1977, the Heathkit H11 was announced; a PDP-11 in kit form. At the beginning of the 1980s, DEC built the VT180 (codenamed "Robin"), which was a VT100 terminal with an added Z80 -based microcomputer running CP/M , but this product

3220-476: Is split in half; the right 18 bits contains the program counter and the left 13 bits contains the processor status flags , with five zeros between the two sections. The condition register bits, which record the results of arithmetic operations ( e.g. overflow), can be accessed by only a few instructions. In the original KA-10 systems, these registers are simply the first 16 words of main memory . The "fast registers" hardware option implements them as registers in

3335-645: Is usually in the form of a microchip or other hardware that requires an external power source to enable data to persist. Non-volatile memory is considered static, or storage-type memory. This means that you can write data to it, and that information will persist even in the absence of a power source. Typically read-write speeds are limited to its bandwidth or have mechanical limitations of either rotation speeds and arm movement delays for storage types such as Cloud Storage , Hard Disk Drive or CD-RWs , DVD-RWs , SD cards , Solid State Drive , SRAM , and DRAM , or other integrated circuitry . San Francisco in 1956, IBM

3450-727: The SAGE system for the US Air Force , which used large screens and light guns to allow operators to interact with radar data stored in the computer. When the Air Force project wound down, the Lab turned their attention to an effort to build a version of the Whirlwind using transistors in place of vacuum tubes . In order to test their new circuitry, they first built a small 18-bit machine known as TX-0 , which first ran in 1956. When

3565-403: The instruction cycle and instead begins processing at the address stored in the first of those two locations. It is up to the interrupt handler to turn off the interrupt level when it is complete, which it can do by running a CONO, DATA or BLK instruction. Two of the device numbers are set aside for special purposes. Device 0 is the computer's front-panel console; reading that device retrieves

PDP-10 - Misplaced Pages Continue

3680-520: The minicomputer market starting in the early 1960s. The company produced a series of machines known as the PDP line, with the PDP-8 and PDP-11 being among the most successful minis in history. Their success was only surpassed by another DEC product, the late-1970s VAX "supermini" systems that were designed to replace the PDP-11. Although a number of competitors had successfully competed with Digital through

3795-399: The trademark Digital , was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until he was forced to resign in 1992, after the company had gone into precipitous decline. The company produced many different product lines over its history. It is best known for the work in

3910-802: The "11" architecture was soon the industry leader, propelling DEC back to a strong market position. The design was later expanded to allow paged physical memory and memory protection features, useful for multitasking and time-sharing . Some models supported separate instruction and data spaces for an effective virtual address size of 128 KB within a physical address size of up to 4 MB. Smaller PDP-11s, implemented as single-chip CPUs, continued to be produced until 1996, by which time over 600,000 had been sold. The PDP-11 supported several operating systems, including Bell Labs ' new Unix operating system as well as DEC's DOS-11 , RSX-11 , IAS, RT-11 , DSM-11, and RSTS/E . Many early PDP-11 applications were developed using standalone paper-tape utilities. DOS-11

4025-543: The "Digital Laboratory Module" line. The Modules consisted of a number of individual electronic components and germanium transistors mounted to a circuit board , the actual circuits being based on those from the TX-2. The Laboratory Modules were packaged in an extruded aluminum housing, intended to sit on an engineer's workbench, although a rack-mount bay was sold that held nine laboratory modules. They were then connected together using banana plug patch cords inserted at

4140-439: The "sandbox" for a rising generation of engineers and computer scientists. Large numbers of PDP-11/70s were deployed in telecommunications and industrial control applications. AT&T Corporation became DEC's largest customer. RT-11 provided a practical real-time operating system in minimal memory, allowing the PDP-11 to continue DEC's critical role as a computer supplier for embedded systems . Historically, RT-11 also served as

4255-433: The 1950s, wiped out when new technical developments rendered their platforms obsolete, and even large companies like RCA and General Electric were failing to make a profit in the market. The only serious expression of interest came from Georges Doriot and his American Research and Development Corporation (AR&D). Worried that a new computer company would find it difficult to arrange further financing, Doriot suggested

4370-399: The 1970s, the VAX cemented the company's place as a leading vendor in the computer space. As microcomputers improved in the late 1980s, especially with the introduction of RISC -based workstation machines, the performance niche of the minicomputer was rapidly eroded. By the early 1990s, the company was in turmoil as their mini sales collapsed and their attempts to address this by entering

4485-572: The 1980s, culminating in the NVAX microprocessor implementation and VAX 7000/10000 series in the early 1990s. When a DEC research group demonstrated two prototype microcomputers in 1974—before the debut of the MITS Altair —Olsen chose to not proceed with the project. The company similarly rejected another personal computer proposal in 1977. At the time these systems were of limited utility, and Olsen famously derided them in 1977, stating "There

4600-659: The 20xx series KL machines is based on a DEC bus design called the Massbus . While many attributed the success of the PDP-11 to DEC's decision to make the PDP-11 Unibus an open architecture, DEC reverted to prior philosophy with the KL, making Massbus both unique and proprietary. Consequently, there were no aftermarket peripheral manufacturers who made devices for the Massbus, and DEC chose to price their own Massbus devices, notably

4715-566: The ADD operation has as variants ADDI (add an 18-bit I mmediate constant to a register), ADDM (add register contents to a M emory location), ADDB (add to B oth, that is, add register contents to memory and also put the result in the register). A more elaborate example is HLROM ( H alf L eft to R ight, O nes to M emory), which takes the Left half of the register contents, places them in the Right half of

PDP-10 - Misplaced Pages Continue

4830-535: The AN20 IMP interface was an I/O bus device. Both could run either TOPS-10 or TOPS-20 microcode and thus the corresponding operating system. The later Model B version of the 2060 processors removes the 256 kilo word limit on the virtual address space by supporting up to 32 "sections" of up to 256 kilowords each, along with substantial changes to the instruction set. The two versions are effectively different CPUs. The first operating system that takes advantage of

4945-450: The CPU which allowed one to easily see the logic modules plugged into the wire-wrapped backplane of the CPU. Sold standard with 4 kWords of 12-bit core memory and a Teletype Model 33 ASR for basic input/output, the machine listed for only $ 18,000. The PDP-8 is referred to as the first real minicomputer because of its sub-$ 25,000 price. Sales were, unsurprisingly, very strong, and helped by

5060-486: The CPU, still addressable as the first 16 words of memory. Some software takes advantage of this by using the registers as an instruction cache by loading code into the registers and then jumping to the appropriate address; this is used, for example, in Maclisp to implement one version of the garbage collector . Later models all have registers in the CPU. There are two operational modes, supervisor and user mode. Besides

5175-592: The KL-10; extended addressing, which changes the process of generating the effective address of an instruction, is briefly discussed at the end. Generally, the system has 36-bit words and instructions, and 18-bit addresses. Note that the bit numbering order is different from some other DEC processors, and many newer processors. There are 16 general-purpose, 36-bit registers. The right half of these registers (other than register 0) may be used for indexing. A few instructions operate on pairs of registers. The "PC Word" register

5290-619: The Model B's capabilities is TOPS-20 release 3, and user mode extended addressing is offered in TOPS-20 release 4. TOPS-20 versions after release 4.1 only run on a Model B. TOPS-10 versions 7.02 and 7.03 also use extended addressing when run on a 1090 (or 1091) Model B processor running TOPS-20 microcode. The final upgrade to the KL10 was the MCA25 upgrade of a 2060 to 2065 (or a 1091 to 1095), which gave some performance increases for programs which run in multiple sections. The I/O architecture of

5405-517: The PC, but was more expensive than, and completely incompatible with IBM PC hardware and software, offering far fewer options for customizing a system. Unlike CP/M and DOS microcomputers, every copy of every program for the Professional had to be provided with a unique key for the particular machine and CPU for which it was bought. At that time this was mainstream policy, because most computer software

5520-474: The PDP-10 looms large in early hacker folklore . Projects to extend the PDP-10 line were eclipsed by the success of the unrelated VAX superminicomputer , and the cancellation of the PDP-10 line was announced in 1983. According to reports, DEC sold "about 1500 DECsystem-10s by the end of 1980." The original PDP-10 processor is the KA10, introduced in 1968. It uses discrete transistors packaged in DEC's Flip-Chip technology, with backplanes wire wrapped via

5635-465: The PDP-11 to start the main processor, which is typically booted from the same RP06 disk drive as the PDP-11. The PDP-11 performs watchdog functions once the main processor is running. Communication with IBM mainframes, including Remote Job Entry (RJE), was accomplished via a DN61 or DN-64 front-end processor, using a PDP-11/40 or PDP-11/34a. The KS10 is a lower-cost PDP-10 built using AMD 2901 bit-slice chips, with an Intel 8080A microprocessor as

5750-630: The PDP-8, all in software. Although not a huge seller, 142 LINC-8s were sold starting at $ 38,500. Like the original LINC to PDP-5 evolution, the LINC-8 was then modified into the single-processor PDP-12 , adding another 1000 machines to the 12-bit family. Newer circuitry designs led to the PDP-8/I and PDP-8/L in 1968. In 1975, one year after an agreement between DEC and Intersil , the Intersil 6100 chip

5865-459: The PDP-9 was a big seller, eventually selling 445 machines, more than all of the earlier models combined. Even while the PDP-9 was being introduced, its replacement was being designed, and was introduced as 1969's PDP-15 , which re-implemented the PDP-9 using integrated circuits in place of modules. Much faster than the PDP-9 even in basic form, the PDP-15 also included a floating point unit and

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5980-700: The Professional was a superior machine, running inferior software. In addition, a new user would have to learn an awkward, slow, and inflexible menu-based user interface which appeared to be radically different from PC DOS or CP/M , which were more commonly used on the 8080- and 8088-based microcomputers of the time. A second offering, the DECmate II was the latest version of the PDP-8-based word processors, but not really suited to general computing, nor competitive with Wang Laboratories ' popular word processing equipment. The most popular early DEC microcomputer

6095-539: The RP06 disk drive, at a substantial premium above comparable IBM-compatible devices. CompuServe for one, designed its own alternative disk controller that could operate on the Massbus, but connect to IBM style 3330 disk subsystems. The KL class machines have a PDP-11/40 front-end processor for system start-up and monitoring. The PDP-11 is booted from a dual-ported RP06 disk drive (or alternatively from an 8" floppy disk drive or DECtape ), and then commands can be given to

6210-511: The Rainbow, and in its standard form was the first widely marketed diskless workstation . In 1984, DEC launched its first 10 Mbit/s Ethernet . Ethernet allowed scalable networking, and VAXcluster allowed scalable computing. Combined with DECnet and Ethernet-based terminal servers ( LAT ), DEC had produced a networked storage architecture which allowed them to compete directly with IBM. Ethernet replaced Token Ring , and went on to become

6325-492: The System Modules to build their "Memory Test" machine for testing core memory systems, selling about 50 of these pre-packaged units over the next eight years. The PDP-1 and LINC computers were also built using System Modules (see below). Modules were part of DEC's product line into the 1970s, although they went through several evolutions during this time as technology changed. The same circuits were then packaged as

6440-469: The TX-0 successfully proved the basic concepts, attention turned to a much larger system, the 36-bit TX-2 with a then-enormous 64 kWords of core memory . Core was so expensive that parts of TX-0's memory were stripped for the TX-2, and what remained of the TX-0 was then given to MIT on permanent loan. At MIT, Ken Olsen and Harlan Anderson noticed something odd: students would line up for hours to get

6555-436: The ability to address more memory, often by extending the address format to 18 or 24-bits in machines were otherwise similar to their earlier 16-bit designs. In contrast, DEC decided to make a more radical departure. In 1976, they began the design of a machine whose entire architecture was expanded from the 16-bit PDP-11 to a new 32-bit basis. This would allow the addressing of very large memories, which were to be controlled by

6670-515: The adoption of "\" for pathnames in MS-DOS and Microsoft Windows as opposed to "/" in Unix . The evolution of the PDP-11 followed earlier systems, eventually including a single-user deskside personal computer form, the MicroPDP-11. In total, around 600,000 PDP-11s of all models were sold, and a wide variety of third-party peripheral vendors had also entered the computer product ecosystem. It

6785-422: The aforementioned tape drives could read/write from/to 200 BPI , 556 BPI and 800 BPI IBM-compatible tapes. The TM10 Magtape controller was available in two submodels: From the first PDP-6s to the KL-10 and KS-10, the user-mode instruction set architecture is largely the same. This section covers that architecture. The only major change to the architecture is the addition of multi-section extended addressing in

6900-587: The architecture are two's complement 36-bit integer arithmetic (including bitwise operations), 36-bit floating-point, and halfwords. Extended, 72-bit, floating point is supported through special instructions designed to be used in multi-instruction sequences. Byte pointers are supported by special instructions. A word structured as a "count" half and a "pointer" half facilitates the use of bounded regions of memory, notably stacks . Instructions are stored in 36-bit words. There are two formats, general instructions and input/output instructions. In general instructions,

7015-460: The basis for the new design, although when they first viewed the proposal, management was not impressed and almost cancelled it. The result was the PDP-11 , released in 1970. It differed from earlier designs considerably. In particular, the new design did not include many of the addressing modes that were intended to make programs smaller in memory, a technique that was widely used on other DEC machines and CISC designs in general. This would mean

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7130-451: The better-established vendors like IBM or Honeywell , in spite of its low cost around $ 300,000. Only 23 were sold, or 26 depending on the source, and unlike other models the low sales meant the PDP-6 was not improved with successor versions. However, the PDP-6 is historically important as the platform that introduced "Monitor", an early time-sharing operating system that would evolve into

7245-774: The company's first computer, the PDP-1 . In keeping with Doriot's instructions, the name was an initialism for " Programmable Data Processor ", leaving off the term "computer". As Gurley put it, "We aren't building computers, we're building 'Programmable Data Processors'." The prototype was first shown publicly at the Joint Computer Conference in Boston in December 1959. The first PDP-1 was delivered to Bolt, Beranek and Newman in November 1960, and formally accepted

7360-411: The compatible DECSYSTEM-20 , along with a TOPS-20 operating system that included virtual memory support. The Jupiter Project was supposed to continue the mainframe product line into the future by using gate arrays with an innovative Air Mover Cooling System, coupled with a built-in floating point processing engine called "FBOX". The design was intended for a top tier scientific computing niche, yet

7475-445: The corresponding bits in the left half of register A. If all those bits are E qual to zero, skip the next instruction; and in any case, replace those bits by their Boolean complement. Some smaller instruction classes include the shift/rotate instructions and the procedure call instructions. Particularly notable are the stack instructions PUSH and POP, and the corresponding stack call instructions PUSHJ and POPJ. The byte instructions use

7590-431: The counter as well as moving to the next location in memory. It then performs a DATAO or DATAI. Finally, it checks the counter side of the value at E, if it is non-zero, it skips the next instruction. If it is zero, it performs the next instruction, normally a JUMP back to the top of the loop. The BLK instructions are effectively small programs that loop over a DATA and increment instructions, but by having this implemented in

7705-486: The critical performance measurement was based upon COBOL compilation which did not fully utilize the primary design features of Jupiter technology. When the Jupiter Project was cancelled in 1983, some of the engineers adapted aspects of the 36-bit design into a forthcoming 32-bit design, releasing the high-end VAX8600 in 1985. DEC's successful entry into the computer market took place during a fundamental shift in

7820-473: The difference in memory referencing described above, supervisor-mode programs can execute input/output operations. Communication from user-mode to supervisor-mode is done through Unimplemented User Operations (UUOs): instructions which are not defined by the hardware, and are trapped by the supervisor. This mechanism is also used to emulate operations which may not have hardware implementations in cheaper models. The major datatypes which are directly supported by

7935-481: The dominant networking model in use today. In September 1985, DEC became the fifth company to register a .com domain name (dec.com). Read-write The term might also refer to memory locations having both read and write permissions. In modern computer systems using memory segmentation , each segment has a length and set of permissions associated with it. Read–write memory is composed of either volatile or non-volatile types of storage. Volatile memory

8050-473: The fact that several competitors had just entered the market with machines aimed directly at the PDP-5's market space, which the PDP-8 trounced. This gave the company two years of unrestricted leadership, and eventually 1450 "straight eight" machines were produced before it was replaced by newer implementations of the same basic design. DEC hit an even lower price-point with the PDP-8/S, the S for "serial". As

8165-475: The first "R" (red) series " Flip-Chip " modules. Later, other Flip-Chip module series provided additional speed, much higher logic density, and industrial I/O capabilities. DEC published extensive data about the modules in free catalogs that became very popular. With the company established and a successful product on the market, DEC turned its attention to the computer market once again as part of its planned "Phase II". In August 1959, Ben Gurley started design of

8280-487: The fledgling company change its business plan to focus less on computers, and even change their name from "Digital Computer Corporation". The pair returned with an updated business plan that outlined two phases for the company's development. They would start by selling computer modules as stand-alone devices that could be purchased separately and wired together to produce a number of different digital systems for lab use. Then, if these "digital modules" were able to build

8395-411: The front of the modules. Three versions were offered, running at 5 MHz (1957), 500 kHz (1959), or 10 MHz (1960). The Modules proved to be in high demand by other computer companies, who used them to build equipment to test their own systems. Despite the recession of the late 1950s, the company sold $ 94,000 worth of these modules during 1958 alone (equivalent to $ 992,700 in 2023), turning

8510-512: The high-end market with machines like the VAX 9000 were market failures. After several attempts to enter the workstation and file server market, the DEC Alpha product line began to make successful inroads in the mid-1990s, but was too late to save the company. DEC was acquired in June 1998 by Compaq in what was at that time the largest merger in the history of the computer industry. During

8625-555: The indirect bit is 1, the value at E is fetched and the effective address calculation is repeated. If I is 1 in the stored value at E in memory, the system will then indirect through that address as well, possibly following many such steps. This process continues until an indirect word with a zero indirect bit is reached. Indirection of this sort was a common feature of processor designs of this era. In supervisor mode, addresses correspond directly to physical memory. In user mode, addresses are translated to physical memory. Earlier models give

8740-413: The inspiration for many microcomputer OS's, as these were generally being written by programmers who cut their teeth on one of the many PDP-11 models. For example, CP/M used a command syntax similar to RT-11's, and even retained the awkward PIP program used to copy data from one computer device to another. As another historical footnote, DEC's use of "/" for "switches" (command-line options) would lead to

8855-490: The lab's various computer projects. The Lab is best known for their work on what would today be known as "interactivity", and their machines were among the first where operators had direct control over programs running in real-time. These had started in 1944 with the famed Whirlwind , which was originally developed to make a flight simulator for the US Navy , although this was never completed. Instead, this effort evolved into

8970-450: The leftmost 9 bits, 0 to 8, contain an instruction opcode . Many of the possible 512 codes are not defined in the base model machines and are reserved for expansion like the addition of a hardware floating point unit . Following the opcode in bits 9 to 12 is the number of a register which will be used for the instruction. The input/output instructions all start with bits 0 through 2 being set to 1 (decimal value 7), bits 3 through 9 containing

9085-548: The limited information available, they used it to process radar cross section data for the Lockheed A-12 reconnaissance aircraft . Gordon Bell remembered that it was being used in Oregon some time later, but could not recall who was using it. In November 1962, DEC introduced the $ 65,000 PDP-4 . The PDP-4 was similar to the PDP-1 and used a similar instruction set, but used slower memory and different packaging to lower

9200-441: The lines were shut down in early 1967. Like the PDP-1 before it, the PDP-5 inspired a series of newer models based on the same basic design that would go on to be more famous than its parent. On March 22, 1965, DEC introduced the PDP-8 , which replaced the PDP-5's modules with the new R-series modules using Flip Chips. The machine was re-packaged into a small tabletop case, which remains distinctive for its use of smoked plastic over

9315-496: The machine would cost much less than the larger systems then available, it would also be able to serve users that needed a lower-cost solution dedicated to a specific task, where a larger 36-bit machine would not be needed. In 1957, when the pair and Ken's brother Stan sought capital, they found that the American business community was hostile to investing in computer companies. Many smaller computer companies had come and gone in

9430-438: The machine would spend more time accessing memory, which would slow it down. However, the machine also extended the idea of multiple "General Purpose Registers" (GPRs), which gave the programmer flexibility to use these high-speed memory caches as they needed, potentially addressing the performance issues. A major advance in the PDP-11 design was DEC's Unibus , which supported all peripherals through memory mapping . This allowed

9545-738: The main Scheduler might come from one university, the Disk Service from another, and so on. The commercial timesharing services such as CompuServe , On-Line Systems, Inc. (OLS), and Rapidata maintained sophisticated inhouse systems programming groups so that they could modify the operating system as needed for their own businesses without being dependent on DEC or others. There are also strong user communities such as DECUS through which users can share software that they have developed. Digital Equipment Corporation Digital Equipment Corporation ( DEC / d ɛ k / ), using

9660-484: The main processor. The 8080 switches modes after the operating system boots and controls the console and remote diagnostic serial ports. Two models of tape drives were supported by the TM10 Magnetic Tape Control subsystem: A mix of up to eight of these could be supported, using seven-track or nine-track devices. The TU20 and TU30 each came in A (9-track) and B (7-track) versions, and all of

9775-488: The memory location, and replaces the left half of the memory location with Ones. Halfword instructions are also used for linked lists: HLRZ is the Lisp CAR operator; HRRZ is CDR. The conditional jump operations examine register contents and jump to a given location depending on the result of the comparison. The mnemonics for these instructions all start with JUMP, JUMPA meaning "jump always" and JUMP meaning "jump never" – as

9890-425: The name implies the /S used a serial arithmetic unit, which was much slower but reduced costs so much that the system sold for under $ 10,000. DEC then used the new PDP-8 design as the basis for a new LINC, the two-processor LINC-8 . The LINC-8 used one PDP-8 CPU and a separate LINC CPU, and included instructions to switch from one to the other. This allowed customers to run their existing LINC programs, or "upgrade" to

10005-472: The next 12 bits reserved, and the remaining bits being an indirect bit, a 4-bit register code, and an 18-bit displacement, or a "global indirect word", with its uppermost bit clear, the next bit being an indirect bit, the next 4 bits being a register code, and the remaining 30 bits being a displacement. The process of calculating the effective address generates a 12-bit section number and an 18-bit offset within that segment. The original PDP-10 operating system

10120-458: The next April. The PDP-1 sold in basic form for $ 120,000 (equivalent to $ 9,269,291 in 2023). By the time production ended in 1969, 53 PDP-1s had been delivered. The PDP-1 was supplied standard with 4096 words of core memory , 18-bits per word, and ran at a basic speed of 100,000 operations per second. It was constructed using many System Building Blocks that were packaged into several 19-inch racks . The racks were themselves packaged into

10235-400: The next instruction (which is often an unconditional jump) depending on the result of the comparison. A simple example is CAMN A,LOC which compares the contents of register A with the contents of location LOC and skips the next instruction if they are not equal. A more elaborate example is TLCE A,LOC (read "Test Left Complement, skip if Equal"), which using the contents of LOC as a mask, selects

10350-547: The original PDP-10 memory bus, with external memory modules. Module in this context meant a cabinet, dimensions roughly (WxHxD) 30 x 75 x 30 in. with a capacity of 32 to 256 kWords of magnetic-core memory . The processors used in the DECSYSTEM-20 (2040, 2050, 2060, 2065), commonly but incorrectly called "KL20", use internal memory, mounted in the same cabinet as the CPU . The 10xx models also have different packaging; they come in

10465-539: The original tall PDP-10 cabinets, rather than the short ones used later on for the DECSYSTEM-20. The differences between the 10xx and 20xx models were primarily which operating system they ran, either TOPS-10 or TOPS-20 . Apart from that, differences are more cosmetic than real; some 10xx systems have "20-style" internal memory and I/O, and some 20xx systems have "10-style" external memory and an I/O bus. In particular, all ARPAnet TOPS-20 systems had an I/O bus because

10580-581: The price. Like the PDP-1, about 54 PDP-4s were eventually sold, most to a customer base similar to the original PDP-1. In 1964, DEC introduced its new Flip Chip module design, and used it to re-implement the PDP-4 as the PDP-7 . The PDP-7 was introduced in December 1964, and about 120 were eventually produced. An upgrade to the Flip Chip led to the R series, which in turn led to the PDP-7A in 1965. The PDP-7

10695-408: The processor itself, it avoids the need to repeatedly read the series of instructions from main memory and thus performs the loop much more rapidly. The final set of I/O instructions are used to write and read condition codes on the device, CONO and CONI. Additionally, CONSZ will perform a CONI, bitmask the retrieved data against the value in E, and then skip the next instruction if it is zero, used in

10810-714: The purchase, some parts of DEC were sold to other companies; the compiler business and the Hudson Fab were sold to Intel . At the time, Compaq was focused on the enterprise market and had recently purchased several other large vendors. DEC was a major player overseas where Compaq had less presence. However, Compaq had little idea what to do with its acquisitions, and soon found itself in financial difficulty of its own. Compaq subsequently merged with Hewlett-Packard (HP) in May 2002. Ken Olsen and Harlan Anderson were two engineers who had been working at MIT Lincoln Laboratory on

10925-418: The same 36-bit word length and slightly extending the instruction set. The main difference was a greatly improved hardware implementation. Some aspects of the instruction set are unusual, most notably the byte instructions, which operate on bit fields of any size from 1 to 36 bits inclusive, according to the general definition of a byte as a contiguous sequence of a fixed number of bits . The PDP-10

11040-607: The same design. During construction of the prototype PDP-1, some design work was carried out on a 24-bit PDP-2, and the 36-bit PDP-3. Although the PDP-2 never proceeded beyond the initial design, the PDP-3 found some interest and was designed in full. Only one PDP-3 appears to have been built, in 1960, by the CIA's Scientific Engineering Institute (SEI) in Waltham, Massachusetts . According to

11155-409: The settings of the panel switches while writing lights up the status lamps. Device 4 is the "priority interrupt", which can be read using CONI to gain additional information about an interrupt that has occurred. In processors supporting extended addressing, the address space is divided into "sections". An 18-bit address is a "local address", containing an offset within a section, and a "global address"

11270-418: The ultimate effective address used by the instruction is not E, but the address stored in memory location E. When using indirection, the data in word E is interpreted in the same way as the layout of the instruction; bits 0 to 12 are ignored, and 13 through 35 form I, X and Y as above. Instruction execution begins by calculating E. It adds the contents of the given register X (if not 0) to the offset Y; then, if

11385-489: The underlying organization of the machines from word lengths based on 6-bit characters to those based on 8-bit words needed to support ASCII . DEC began studies of such a machine, the PDP-X, but Ken Olsen did not support it as he could not see how it offered anything their existing 12-bit or 18-bit machines didn't. This led the leaders of the PDP-X project to leave DEC and start Data General , whose 16-bit Data General Nova

11500-467: The widely used TOPS-10 . When newer Flip Chip packaging allowed the PDP-6 to be re-implemented at a much lower cost, DEC took the opportunity to refine their 36-bit design, introducing the PDP-10 in 1968. The PDP-10 was as much a success as the PDP-6 was a commercial failure; about 700 mainframe PDP-10s were sold before production ended in 1984. The PDP-10 was widely used in university settings, and thus

11615-478: Was either bought from the company that built the computer or custom-constructed for one client. However, the emerging third-party software industry disregarded the PDP-11/Professional line and concentrated on other microcomputers where distribution was easier. At DEC itself, creating better programs for the Professional was not a priority, perhaps from fear of cannibalizing the PDP-11 line. As a result,

11730-507: Was even sold in kit form as the Heathkit H11 , although it proved too expensive for Heathkit 's traditional hobbyist market. The introduction of semiconductor memory in the early 1970s, and especially dynamic RAM shortly thereafter, led to dramatic reductions in the price of memory as the effects of Moore's Law were felt. Within years, it was common to equip a machine with all the memory it could address, typically 64 KB on 16-bit machines. This led vendors to introduce new designs with

11845-623: Was eventually ported along with MS-DOS 2.0 and introduced in late 1983. Although the Rainbow generated some press, it was unsuccessful due to its high price and lack of marketing and sales support. By late 1983 IBM was outselling DEC's personal computers by more than ten to one. A further system was introduced in 1986 as the VAXmate , which included Microsoft Windows 1.0 and used VAX/VMS-based file and print servers along with integration into DEC's own DECnet -family, providing LAN/WAN connection from PC to mainframe or supermini. The VAXmate replaced

11960-636: Was followed by the even more successful VT100 and its follow-ons, making DEC one of the largest terminal vendors in the industry. This was supported by a line of inexpensive computer printers , the DECwriter line. With the VT and DECwriter series, DEC could now offer a complete top-to-bottom system from computer to all peripherals, which formerly required collecting the required devices from different suppliers. The VAX processor architecture and family of systems evolved and expanded through several generations during

12075-416: Was found in many university computing facilities and research labs during the 1970s, the most notable being Harvard University 's Aiken Computation Laboratory, MIT 's AI Lab and Project MAC , Stanford 's SAIL , Computer Center Corporation (CCC), ETH (ZIR), and Carnegie Mellon University . Its main operating systems , TOPS-10 and TENEX , were used to build out the early ARPANET . For these reasons,

12190-731: Was initially available only to DEC employees. It was only after IBM had successfully launched the IBM PC in 1981 that DEC responded with their own systems. In 1982, DEC introduced not one, but three incompatible machines which were each tied to different proprietary architectures. The first, the DEC Professional , was based on the PDP-11/23 (and later, the 11/73) running the RSX-11M+ derived, but menu-driven, P/OS ("Professional Operating System"). This DEC machine easily outperformed

12305-498: Was launched, effectively a PDP-8 on a chip. This was a way to allow PDP-8 software to be run even after the official end-of-life announcement for the DEC PDP-8 product line. While the PDP-5 introduced a lower-cost line, 1963's PDP-6 was intended to take DEC into the mainframe market with a 36-bit machine. However, the PDP-6 proved to be a "hard sell" with customers, as it offered few obvious advantages over similar machines from

12420-539: Was released in 1969 and was a huge success. The success of the Nova finally prompted DEC to take the switch seriously, and they began a crash program to introduce a 16-bit machine of their own. The new system was designed primarily by Harold McFarland, Gordon Bell , Roger Cady, and others. The project was able to leap forward in design with the arrival of Harold McFarland, who had been researching 16-bit designs at Carnegie Mellon University . One of his simpler designs became

12535-457: Was simply called "Monitor", but was later renamed TOPS-10 . Eventually the PDP-10 system itself was renamed the DECsystem-10. Early versions of Monitor and TOPS-10 formed the basis of Stanford's WAITS operating system and the CompuServe time-sharing system. Over time, some PDP-10 operators began running operating systems assembled from major components developed outside DEC. For example,

12650-610: Was slightly faster than the newer VAX-11/750 , although more limited in memory. A smaller, less expensive model, the KS10, was introduced in 1978, using TTL and Am2901 bit-slice components and including the PDP-11 Unibus to connect peripherals. The KS10 was marketed as the DECSYSTEM-2020, part of the DECSYSTEM-20 range; it was DEC's entry in the distributed processing arena, and it was introduced as "the world's lowest cost mainframe computer system." The KA10 has

12765-404: Was the PDP-11's first disk operating system, but was soon supplanted by more capable systems. RSX provided a general-purpose multitasking environment and supported a wide variety of programming languages . IAS was a time-sharing version of RSX-11D. Both RSTS and Unix were time-sharing systems available to educational institutions at little or no cost, and these PDP-11 systems were destined to be

12880-454: Was the basis of many advances in computing and operating system design during the 1970s. DEC later re-branded all of the models in the 36-bit series as the "DECsystem-10", and PDP-10s are generally referred to by the model of their CPU, starting with the "KA10", soon upgraded to the "KI10" (I:Integrated circuit); then to "KL10" (L:Large-scale integration ECL logic ); also the "KS10" (S: Small form factor ). Unified product line upgrades produced

12995-535: Was the dual-processor (Z80 and 8088) Rainbow 100 , which ran the 8-bit CP/M operating system on the Z80 and the 16-bit CP/M-86 operating system on the Intel 8088 processor. It could also run a UNIX System III implementation called VENIX . Applications from standard CP/M could be re-compiled for the Rainbow, but by this time users were expecting custom-built (pre-compiled binary) applications such as Lotus 1-2-3 , which

13110-535: Was the top-of-the-line Uni-processor KA machine at the time when the PA1050 software package was introduced. Two other KA10 models were the uniprocessor 10/40, and the dual-processor 10/55. The KI10 introduced support for paged memory management, and also support a larger physical address space of 4 megawords . KI10 models include 1060, 1070 and 1077, the latter incorporating two CPUs. The original KL10 PDP-10 (also marketed as DECsystem-10) models (1080, 1088, etc.) use

13225-441: Was used as a printer . The Soroban system was notoriously unreliable, and often replaced with a modified Friden Flexowriter , which also contained its own punched tape system. A variety of more-expensive add-ons followed, including magnetic tape systems, punched card readers and punches, and faster punched tape and printer systems. When DEC introduced the PDP-1, they also mentioned larger machines at 24, 30 and 36 bits, based on

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