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104-601: PDP-10 computers running the TOPS-10 operating system were labeled DECsystem-10 as a way of differentiating them from the PDP-11 . Later on, those systems running TOPS-20 (on the KL10 PDP-10 processors) were labeled DECSYSTEM-20 (the block capitals being the result of a lawsuit brought against DEC by Singer , which once made a computer called " The System Ten "). The DECSYSTEM-20 was sometimes called PDP-20 , although this designation

208-475: A flatbed scanner to take ultra-high-resolution photographs or using an optical mouse as barcode reader . A solution or feat has "hack value" if it is done in a way that has finesse, cleverness or brilliance, which makes creativity an essential part of the meaning. For example, picking a difficult lock has hack value; smashing it does not. As another example, proving Fermat's Last Theorem by linking together most of modern mathematics has hack value; solving

312-473: A "hack" refers to a program that (sometimes illegally) modifies another program, often a video game, giving the user access to features otherwise inaccessible to them. As an example of this use, for Palm OS users (until the 4th iteration of this operating system ), a "hack" refers to an extension of the operating system which provides additional functionality. Term also refers to those people who cheat on video games using special software. This can also refer to

416-517: A 2065 running TOPS-10, which was available to interested parties via SSH upon registration (at no cost) at their website. PDP-10 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

520-440: A combinatorial problem by exhaustively trying all possibilities does not. Hacking is not using process of elimination to find a solution; it's the process of finding a clever solution to a problem. While using hacker to refer to someone who enjoys playful cleverness is most often applied to computer programmers, it is sometimes used for people who apply the same attitude to other fields. For example, Richard Stallman describes

624-567: 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

728-584: 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

832-566: A critically large population and encouraged the spread of a conscious, common, and systematic ethos. Symptomatic of this evolution were an increasing adoption of common slang and a shared view of history, similar to the way in which other occupational groups have professionalized themselves, but without the formal credentialing process characteristic of most professional groups. Over time, the academic hacker subculture has tended to become more conscious, more cohesive, and better organized. The most important consciousness-raising moments have included

936-461: 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

1040-416: 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

1144-546: A different end, to get inside cultural systems on the net and make them do things they were never intended to do. A successful software and hardware hacker artist is Mark Lottor (mkl), who has created the 3-D light art projects entitled the Cubatron , and the Big Round Cubatron . This art is made using custom computer technology, with specially designed circuit boards and programming for microprocessor chips to manipulate

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1248-580: A fake police car atop the dome on MIT's Building 10, that was a hack in this sense, and the students involved were therefore hackers. Other types of hacking are reality hackers , wetware hackers ("hack your brain"), and media hackers ("hack your reputation"). In a similar vein, a "hack" may refer to a math hack, that is, a clever solution to a mathematical problem. All of these uses have spread beyond MIT. CSO Online defined ethical hacking as going into devices and computer systems belonging to an organization, with its explicit permissions, to assess and test

1352-613: 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

1456-436: A hacker is a person who follows a spirit of playful cleverness and loves programming. It is found in an originally academic movement unrelated to computer security and most visibly associated with free software , open source and demoscene . It also has a hacker ethic , based on the idea that writing software and sharing the result on a voluntary basis is a good idea, and that information should be free, but that it's not up to

1560-405: 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

1664-454: A notorious example) to expose or add functionality to a device that was unintended for use by end users by the company who created it. A number of techno musicians have modified 1980s-era Casio SK-1 sampling keyboards to create unusual sounds by doing circuit bending : connecting wires to different leads of the integrated circuit chips. The results of these DIY experiments range from opening up previously inaccessible features that were part of

1768-402: A project undertaken on bad self-advice; 3) an entropy booster; 4) to produce, or attempt to produce, a hack(3)", and "hacker" was defined as "one who hacks, or makes them". Much of TMRC's jargon was later imported into early computing culture, because the club started using a DEC PDP-1 and applied its local model railroad slang in this computing context. Initially incomprehensible to outsiders,

1872-529: 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

1976-536: 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

2080-416: 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

2184-470: 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

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2288-882: 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,

2392-451: 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,

2496-412: Is a subculture of individuals who enjoy—often in collective effort—the intellectual challenge of creatively overcoming the limitations of software systems or electronic hardware (mostly digital electronics ), to achieve novel and clever outcomes. The act of engaging in activities (such as programming or other media ) in a spirit of playfulness and exploration is termed hacking . However,

2600-441: Is always the understanding that a more skillful or technical logician could have produced successful modifications that would not be considered a "hack-job". The definition is similar to other, non-computer based uses of the term "hack-job". For instance, a professional modification of a production sports car into a racing machine would not be considered a hack-job, but a cobbled together backyard mechanic's result could be. Even though

2704-476: 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

2808-417: Is the process of software engines running real-world cyber threats to assess the survivability of a company's digital structure. Ethical hackers play the role of cyber attackers by executing assessments, penetration tests, and modeling tactics, techniques, and procedures used by threat-actors. This careful examination provides an organization with the identification of weaknesses in its security systems, enabling

2912-430: Is worth doing or is interesting. This is something that hackers often feel intuitively about a problem or solution. An aspect of hack value is performing feats for the sake of showing that they can be done, even if others think it is difficult. Using things in a unique way outside their intended purpose is often perceived as having hack value. Examples are using a dot matrix impact printer to produce musical notes, using

3016-476: The LED lights. Don Hopkins is a software hacker artist well known for his artistic cellular automata. This art, created by a cellular automata computer program, generates objects which randomly bump into each other and in turn create more objects and designs, similar to a lava lamp, except that the parts change color and form through interaction. Hopkins Says: Cellular automata are simple rules that are applied to

3120-460: 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 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

3224-554: The University of California, Berkeley and Carnegie Mellon University were particularly well-known hotbeds of early hacker culture. They evolved in parallel, and largely unconsciously, until the Internet , where a legendary PDP-10 machine at MIT, called AI, that was running ITS , provided an early meeting point of the hacker community. This and other developments such as the rise of the free software movement and community drew together

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3328-404: 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

3432-701: The jailbreaking of iPhones . Hacker artists create art by hacking on technology as an artistic medium . This has extended the definition of the term and what it means to be a hacker. Such artists may work with graphics , computer hardware , sculpture , music and other audio , animation , video , software , simulations , mathematics , reactive sensory systems, text, poetry , literature , or any combination thereof. Dartmouth College musician Larry Polansky states: Technology and art are inextricably related. Many musicians, video artists, graphic artists, and even poets who work with technology—whether designing it or using it—consider themselves to be part of

3536-479: The 'hacker community.' Computer artists, like non-art hackers, often find themselves on society's fringes, developing strange, innovative uses of existing technology. There is an empathetic relationship between those, for example, who design experimental music software and hackers who write communications freeware . Another description is offered by Jenny Marketou: Hacker artists operate as culture hackers who manipulate existing techno- semiotic structures towards

3640-588: The 1960s around the Massachusetts Institute of Technology (MIT)'s Tech Model Railroad Club (TMRC) and MIT Artificial Intelligence Laboratory . Hacking originally involved entering restricted areas in a clever way without causing any major damage. Some famous hacks at the Massachusetts Institute of Technology were placing of a campus police cruiser on the roof of the Great Dome and converting

3744-688: 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

3848-555: 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

3952-530: 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

4056-654: The Bazaar and many other essays, maintainer of the Jargon File (which was previously maintained by Guy L. Steele, Jr. ). Within the computer programmer subculture of hackers, the term hacker is also used for a programmer who reaches a goal by employing a series of modifications to extend existing code or resources. In this sense, it can have a negative connotation of using inelegant kludges to accomplish programming tasks that are quick, but ugly, inelegant, difficult to extend, hard to maintain and inefficient. This derogatory form of

4160-528: 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

4264-641: The Great Dome into R2-D2 . Richard Stallman explains about hackers who program: What they had in common was mainly love of excellence and programming. They wanted to make their programs that they used be as good as they could. They also wanted to make them do neat things. They wanted to be able to do something in a more exciting way than anyone believed possible and show "Look how wonderful this is. I bet you didn't believe this could be done." Hackers from this subculture tend to emphatically differentiate themselves from whom they pejoratively call " crackers "; those who are generally referred to by media and members of

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4368-683: The Homebrew Club's days, but the interests and values of both communities somewhat diverged. Today, the hobbyists focus on commercial computer and video games , software cracking and exceptional computer programming ( demo scene ). Also of interest to some members of this group is the modification of computer hardware and other electronic devices, see modding . Electronics hobbyists working on machines other than computers also fall into this category. This includes people who do simple modifications to graphing calculators , video game consoles , electronic musical keyboards or other device (see CueCat for

4472-588: 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

4576-552: The Late Middle English words hackere, hakker, or hakkere - one who cuts wood, woodchopper, or woodcutter. Although the idea of "hacking", in the modern sense, existed long before the modern term "hacker"‍—‌with the most notable example of Lightning Ellsworth , it was not a word that the first programmers used to describe themselves. In fact, many of the first programmers were from engineering or physics backgrounds. "But from about 1945 onward (and especially during

4680-610: 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

4784-467: 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

4888-535: 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

4992-422: 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

5096-588: 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,

5200-524: The business's very existence. Furthermore, the act of ethical hacking also molds the larger hacker culture. Hacking skills, traditionally associated with breaking the law, have changed dramatically with the emergence of ethical hacking. Ethical hacking helped legitimize hacking skills which can now be talked about publicly. This shift challenges the stereotypical perception of hackers as criminals, allowing for greater emphasis on their positive contributions to cybersecurity. Ethical hacking has drastically changed

5304-547: The chip design to producing the strange, dis-harmonic digital tones that became part of the techno music style. Companies take different attitudes towards such practices, ranging from open acceptance (such as Texas Instruments for its graphing calculators and Lego for its Lego Mindstorms robotics gear) to outright hostility (such as Microsoft 's attempts to lock out Xbox hackers or the DRM routines on Blu-ray Disc players designed to sabotage compromised players. ) In this context,

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5408-534: The color on the paint cans was Terra Cotta). There were some significant internal differences between the earlier KL10 Model A processors, used in the earlier DECsystem-10s running on KL10 processors, and the later KL10 Model Bs, used for the DECSYSTEM-20s. Model As used the original PDP-10 memory bus, with external memory modules. The later Model B processors used in the DECSYSTEM-20 used internal memory, mounted in

5512-400: The commoditization of computer and networking technology, and has, in turn, accelerated that process. In 1975, hackerdom was scattered across several different families of operating systems and disparate networks; today it is largely a Unix and TCP/IP phenomenon, and is concentrated around various operating systems based on free software and open-source software development. Many of

5616-581: The composition of the first Jargon File in 1973, the promulgation of the GNU Manifesto in 1985, and the publication of Eric Raymond 's The Cathedral and the Bazaar in 1997. Correlated with this has been the gradual recognition of a set of shared culture heroes, including: Bill Joy , Donald Knuth , Dennis Ritchie , Alan Kay , Ken Thompson , Richard M. Stallman , Linus Torvalds , Larry Wall , and Guido van Rossum . The concentration of academic hacker subculture has paralleled and partly been driven by

5720-651: The consciousness of the programmer subculture of hackers include Richard Stallman , the founder of the free software movement and the GNU project , president of the Free Software Foundation and author of the famous Emacs text editor as well as the GNU Compiler Collection (GCC) , and Eric S. Raymond , one of the founders of the Open Source Initiative and writer of the famous text The Cathedral and

5824-445: 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

5928-432: 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

6032-438: The creation of the first ENIAC computer) some programmers realized that their expertise in computer software and technology had evolved not just into a profession, but into a passion" (46). There was a growing awareness of a style of programming different from the cut and dried methods employed at first, but it was not until the 1960s that the term "hackers" began to be used to describe proficient computer programmers. Therefore,

6136-422: The creative attitude of software hackers in fields other than computing. This includes even activities that predate computer hacking, for example reality hackers or urban spelunkers (exploring undocumented or unauthorized areas in buildings). One specific example is clever pranks traditionally perpetrated by MIT students, with the perpetrator being called hacker. For example, when MIT students surreptitiously put

6240-408: The culture is less tolerant of unmaintainable solutions, even when intended to be temporary, and describing someone as a "hacker" might imply that they lack professionalism. In this sense, the term has no real positive connotations, except for the idea that the hacker is capable of doing modifications that allow a system to work in the short term, and so has some sort of marketable skills. However, there

6344-452: The defining characteristic of a hacker is not the activities performed themselves (e.g. programming ), but how it is done and whether it is exciting and meaningful. Activities of playful cleverness can be said to have "hack value" and therefore the term "hacks" came about, with early examples including pranks at MIT done by students to demonstrate their technical aptitude and cleverness. The hacker culture originally emerged in academia in

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6448-470: The desired cultural revolution within the realm of the hacking fraternity. Ethical hacking, on its part through focusing on the constructive application of hacking skills, has become an integral activity in the collective effort towards fortification of cybersecurity and redefining hackers' image in the public eye. In yet another context, a hacker is a computer hobbyist who pushes the limits of software or hardware. The home computer hacking subculture relates to

6552-473: 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

6656-611: The early ARPANET . For these reasons, 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

6760-409: The efficacy of the organization's cybersecurity defenses. Generally, organizations engage the services of ethical hackers either through third-party cybersecurity firms or under contract. Their main job is to identify and fix security gaps before threat-actors find them and exploit them. This proactive approach to cybersecurity testing leads to significant cost savings for organizations. Ethical hacking

6864-438: The elaborate college pranks that...students would regularly devise" (Levy, 1984 p. 10). To be considered a 'hack' was an honor among like-minded peers as "to qualify as a hack, the feat must be imbued with innovation, style and technical virtuosity" (Levy, 1984 p. 10) The MIT Tech Model Railroad Club Dictionary defined hack in 1959 (not yet in a computer context) as "1) an article or project without constructive end; 2)

6968-1186: The fundamental characteristic that links all who identify themselves as hackers is that each is someone who enjoys "…the intellectual challenge of creatively overcoming and circumventing limitations of programming systems and who tries to extend their capabilities" (47). With this definition in mind, it can be clear where the negative implications of the word "hacker" and the subculture of "hackers" came from. Some common nicknames among this culture include "crackers", who are considered to be unskilled thieves who mainly rely on luck, and "phreaks", which refers to skilled crackers and "warez d00dz" (crackers who acquire reproductions of copyrighted software). Hackers who are hired to test security are called "pentesters" or "tiger teams". Before communications between computers and computer users were as networked as they are now, there were multiple independent and parallel hacker subcultures, often unaware or only partially aware of each other's existence. All of these had certain important traits in common: These sorts of subcultures were commonly found at academic settings such as college campuses . The MIT Artificial Intelligence Laboratory ,

7072-476: The general definition of a byte as a contiguous sequence of a fixed number of bits . The PDP-10 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

7176-445: The general public using the term "hacker", and whose primary focus‍—‌be it to malign or for malevolent purposes‍—‌lies in exploiting weaknesses in computer security. The Jargon File , an influential but not universally accepted compendium of hacker slang, defines hacker as "A person who enjoys exploring the details of programmable systems and stretching their capabilities, as opposed to most users, who prefer to learn only

7280-417: The hacker may be the same person.) This usage is common in both programming, engineering and building. In programming, hacking in this sense appears to be tolerated and seen as a necessary compromise in many situations. Some argue that it should not be, due to this negative meaning; others argue that some kludges can, for all their ugliness and imperfection, still have "hack value". In non-software engineering,

7384-525: The hacker subculture". According to Eric S. Raymond , the Open Source and Free Software hacker subculture developed in the 1960s among 'academic hackers' working on early minicomputers in computer science environments in the United States. Hackers were influenced by and absorbed many ideas of key technological developments and the people associated with them. Most notable is the technical culture of

7488-522: The hacker to make it free by breaking into private computer systems. This hacker ethic was publicized and perhaps originated in Steven Levy 's Hackers: Heroes of the Computer Revolution (1984). It contains a codification of its principles. The programmer subculture of hackers disassociates from the mass media's pejorative use of the word 'hacker' referring to computer security, and usually prefer

7592-471: The hands-on imperative. Linus Torvalds , one of the leaders of the open source movement (known primarily for developing the Linux kernel ), has noted in the book The Hacker Ethic that these principles have evolved from the known Protestant ethics and incorporates the spirits of capitalism, as introduced in the early 20th century by Max Weber . Hack value is the notion used by hackers to express that something

7696-502: The hobbyist home computing of the late 1970s, beginning with the availability of MITS Altair . An influential organization was the Homebrew Computer Club . However, its roots go back further to amateur radio enthusiasts. The amateur radio slang referred to creatively tinkering to improve performance as "hacking" already in the 1950s. A large overlaps between hobbyist hackers and the programmer subculture hackers existed during

7800-556: 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

7904-450: 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

8008-654: 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. Hacker culture The hacker culture

8112-431: The main processor to compile and run applications. Separate disk allocations were maintained for all users by the operating system, and various levels of protection could be maintained by for System, Owner, Group, and World users. A model 2060, for example, could typically host up to 40 to 60 simultaneous users before exhibiting noticeably delayed response time. The Living Computer Museum of Seattle, Washington, maintained

8216-473: 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

8320-483: 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

8424-868: The minimum necessary." The Request for Comments (RFC) 1392, the Internet Users' Glossary, amplifies this meaning as "A person who delights in having an intimate understanding of the internal workings of a system, computers and computer networks in particular." As documented in the Jargon File, these hackers are disappointed by the mass media and general public's usage of the word hacker to refer to security breakers , calling them "crackers" instead. This includes both "good" crackers (" white hat hackers "), who use their computer security-related skills and knowledge to learn more about how systems and networks work and to help to discover and fix security holes, as well as those more "evil" crackers (" black hat hackers "), who use

8528-476: 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

8632-400: 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

8736-474: The noun " hack " derives from the everyday English sense "to cut or shape by or as if by crude or ruthless strokes" [Merriam-Webster] and is even used among users of the positive sense of "hacker" who produces "cool" or "neat" hacks. In other words, to "hack" at an original creation, as if with an axe, is to force-fit it into being usable for a task not intended by the original creator, and a "hacker" would be someone who does this habitually. (The original creator and

8840-424: The organization to employ necessary measures towards fortifying its defense. Cyber-attacks can have significant financial implications for a company. In such cases, the organizations could have been saved from these gigantic financial losses by identifying and fixing the vulnerabilities discovered by an ethical hacker. Moreover, for smaller organizations, the impact can be even more dramatic as it can potentially save

8944-538: 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

9048-478: 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

9152-512: The outcome of a race of the two machines could not be assumed, a quick inspection would instantly reveal the difference in the level of professionalism of the designers. The adjective associated with hacker is "hackish" (see the Jargon file ). In a very universal sense, hacker also means someone who makes things work beyond perceived limits in a clever way in general, without necessarily referring to computers, especially at MIT. That is, people who apply

9256-576: The pioneers of the ARPANET , starting in 1969. The PDP-10 AI machine at MIT, running the ITS operating system and connected to the ARPANET, provided an early hacker meeting point. After 1980 the subculture coalesced with the culture of Unix . Since the mid-1990s, it has been largely coincident with what is now called the free software and open source movement . Many programmers have been labeled "great hackers", but

9360-410: 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

9464-453: The public perception of hackers. Rather than viewing persons with hacker skills as perpetrators of cybercrime, they can be viewed as part of the solution in fighting against cybercrime. The ethical hacker with knowledge and expertise stands as guardian to the digital assets, working beforehand alongside organizations to build up a more secure online landscape. Ethical hacking is not only a proactive defense for organizations but also brings about

9568-497: The same cabinet as the CPU . The Model As also had different packaging; they came in the original tall PDP-10 cabinets, rather than the short ones used later on for the DECSYSTEM-20. The last released implementation of DEC's 36-bit architecture was the single cabinet DECSYSTEM-2020, using a KS10 processor. The DECSYSTEM-20 was primarily designed and used as a small mainframe for timesharing . That is, multiple users would concurrently log on to individual user accounts and share use of

9672-445: The same skills to author harmful software (such as viruses or trojans) and illegally infiltrate secure systems with the intention of doing harm to the system. The programmer subculture of hackers, in contrast to the cracker community, generally sees computer security-related activities as contrary to the ideals of the original and true meaning of the hacker term, that instead related to playful cleverness. The word "hacker" derives from

9776-410: 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"

9880-483: The silent composition 4′33″ by John Cage and the 14th-century palindromic three-part piece "Ma Fin Est Mon Commencement" by Guillaume de Machaut as hacks. According to the Jargon File, the word hacker was used in a similar sense among radio amateurs in the 1950s, predating the software hacking community. The Boston Globe in 1984 defined "hackers" as "computer nuts". In their programmer subculture,

9984-598: The slang also became popular in MIT's computing environments beyond the club. Other examples of jargon imported from the club are 'losing' ("when a piece of equipment is not working") and 'munged' ("when a piece of equipment is ruined"). Others did not always view hackers with approval. MIT living groups in 1989 avoided advertising their sophisticated Project Athena workstations to prospective members because they wanted residents who were interested in people, not computers, with one fraternity member stating that "We were worried about

10088-448: The specifics of who that label applies to is a matter of opinion. Certainly major contributors to computer science such as Edsger Dijkstra and Donald Knuth , as well as the inventors of popular software such as Linus Torvalds ( Linux ), and Ken Thompson and Dennis Ritchie ( Unix and C programming language ) are likely to be included in any such list; see also List of programmers . People primarily known for their contributions to

10192-478: The term 'cracker' for that meaning. Complaints about supposed mainstream misuse started as early as 1983, when media used "hacker" to refer to the computer criminals involved in The 414s case. In the programmer subculture of hackers, a computer hacker is a person who enjoys designing software and building programs with a sense for aesthetics and playful cleverness. The term hack in this sense can be traced back to "describe

10296-418: 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

10400-498: The values and tenets of the free and open source software movement stem from the hacker ethics that originated at MIT and at the Homebrew Computer Club . The hacker ethics were chronicled by Steven Levy in Hackers: Heroes of the Computer Revolution and in other texts in which Levy formulates and summarizes general hacker attitudes: Hacker ethics are concerned primarily with sharing, openness, collaboration, and engaging in

10504-408: Was never used by DEC. The following models were produced: The only significant difference the user could see between a DECsystem-10 and a DECSYSTEM-20 was the operating system and the color of the paint. Most (but not all) machines sold to run TOPS-10 were painted "Blasi Blue", whereas most TOPS-20 machines were painted "Terracotta" (often mistakenly called "Chinese Red" or orange; the actual name of

10608-451: 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,

10712-597: 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

10816-534: 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

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