PDP-10 references in JARGON.TXT

Table of Contents


The original JARGON.TXT file was maintained in three locations back in the days of the ARPANET. It was AIWORD.RF[UP,DOC] at SAIL (Stanford A.I. Lab) and GLS;JARGON at MIT-MC and MIT-AI. A snapshot of that file taken 14-Nov-1982 was online at ftp://mc.lcs.mit.edu/its/ai/humor/jargon.68.Z (it is 43K, uncompresses to 87K). [Archive offline, Jan 2001.]

I'm not sure exactly which version of JARGON was used when Guy L. Steele published "The Hacker's Dictionary".

After Eric Raymond published "The New Hacker's Dictionary", the JARGON file grew to 1.1 megabytes but the file hasn't been the same; it has lost a lot of its hacker nature.

has "version 2.9.10 - 16 Jul 1992" in ASCII format.

has "version 3.0.0 - 27 Jul 1993" in HTML format.

A little song

This was found at ftp://sunsite.unc.edu/pub/academic/computer-science/history/pdp-10/docs in the file "pdp10.song". Author unknown.

Oh Lord won't you buy me a PDP-10
My friends all hack Vaxen; I must make amends
Hacked hard all my lifetime, no help from my friends
So Lord, won't you buy me a PDP-10

Oh Lord won't you buy me an RM-03
Faster disk access is trying to find me
I wait for Disk Ready each afternoon 'till 3
So Lord, won't you buy me an RM-03

Oh Lord won't you buy me a disk pack so round
I'm counting on you, Lord, please don't let me down
God, I need a scratch pack; there's none to be found
So Lord won't you buy me a disk pack so round.


/ad'vent/ n. The prototypical computer adventure game, first implemented on the {PDP-10} by Will Crowther as an attempt at computer-refereed fantasy gaming, and expanded into a puzzle-oriented game by Don Woods. Now better known as Adventure, but the {{TOPS-10}} operating system permitted only 6-letter filenames. See also {vadding}.

This game defined the terse, dryly humorous style now expected in text adventure games, and popularized several tag lines that have become fixtures of hacker-speak: "A huge green fierce snake bars the way!" "I see no X here" (for some noun X). "You are in a maze of twisty little passages, all alike." "You are in a little maze of twisty passages, all different." The `magic words' {xyzzy} and {plugh} also derive from this game.

Crowther, by the way, participated in the exploration of the Mammoth & Flint Ridge cave system; it actually *has* a `Colossal Cave' and a `Bedquilt' as in the game, and the `Y2' that also turns up is cavers' jargon for a map reference to a secondary entrance.

From Bill Bourn (30-Oct-95):
I never got to play Adventure myself because I translated that 36-bit fortran to PL/1 for VM/CMS. It wasn't an easy fit on the 32-bit IBM mainframe. I did get a kick out of watching my "testing" cadre stumble around the Colossal Cave though.


1. /aws/ (East Coast), /ay-os/ (West Coast) [based on a PDP-10 increment instruction] vt.,obs. To increase the amount of something. "AOS the campfire." Usage: considered silly, and now obsolete. Now largely supplanted by {bump}. See {SOS}.

Historical note: AOS in sense 1 was the name of a {PDP-10} instruction that took any memory location in the computer and added 1 to it; AOS meant `Add One and do not Skip'. Why, you may ask, does the `S' stand for `do not Skip' rather than for `Skip'? Ah, here was a beloved piece of PDP-10 folklore. There were eight such instructions: AOSE added 1 and then skipped the next instruction if the result was Equal to zero; AOSG added 1 and then skipped if the result was Greater than 0; AOSN added 1 and then skipped if the result was Not 0; AOSA added 1 and then skipped Always; and so on. Just plain AOS didn't say when to skip, so it never skipped.

For similar reasons, AOJ meant `Add One and do not Jump'. Even more bizarre, SKIP meant `do not SKIP'! If you wanted to skip the next instruction, you had to say `SKIPA'. Likewise, JUMP meant `do not JUMP'; the unconditional form was JUMPA. However, hackers never did this. By some quirk of the 10's design, the {JRST} (Jump and ReSTore flag with no flag specified) was actually faster and so was invariably used. Such were the perverse mysteries of assembler programming.


/B-L-T/, /bl*t/ or (rarely) /belt/ n.,vt. Synonym for {blit}. This is the original form of {blit} and the ancestor of {bitblt}. It referred to any large bit-field copy or move operation (one resource-intensive memory-shuffling operation done on pre-paged versions of ITS, WAITS, and TOPS-10 was sardonically referred to as `The Big BLT'). The jargon usage has outlasted the {PDP-10} BLock Transfer instruction from which {BLT} derives; nowadays, the assembler mnemonic {BLT} almost always means `Branch if Less Than zero'.

connector conspiracy

[probably came into prominence with the appearance of the KL-10 (one model of the {PDP-10}), none of whose connectors matched anything else] n. The tendency of manufacturers (or, by extension, programmers or purveyors of anything) to come up with new products that don't fit together with the old stuff, thereby making you buy either all new stuff or expensive interface devices. The KL-10 Massbus connector was actually *patented* by DEC, which reputedly refused to license the design and thus effectively locked third parties out of competition for the lucrative Massbus peripherals market. This is a source of never-ending frustration for the diehards who maintain older PDP-10 or VAX systems. Their CPUs work fine, but they are stuck with dying, obsolescent disk and tape drives with low capacity and high power requirements.


/D-D-T/ n. 1. Generic term for a program that assists in debugging other programs by showing individual machine instructions in a readable symbolic form and letting the user change them. In this sense the term DDT is now archaic, having been widely displaced by `debugger' or names of individual programs like `dbx', `adb', `gdb', or `sdb'.

2. [ITS] Under MIT's fabled {{ITS}} operating system, DDT (running under the alias HACTRN) was also used as the {shell} or top level command language used to execute other programs. 3. Any one of several specific DDTs (sense 1) supported on early DEC hardware. The DEC PDP-10 Reference Handbook (1969) contained a footnote on the first page of the documentation for DDT which illuminates the origin of the term:

Historical footnote: DDT was developed at MIT for the PDP-1 computer in 1961. At that time DDT stood for "DEC Debugging Tape". Since then, the idea of an on-line debugging program has propagated throughout the computer industry. DDT programs are now available for all DEC computers. Since media other than tape are now frequently used, the more descriptive name "Dynamic Debugging Technique" has been adopted, retaining the DDT abbreviation. Confusion between DDT-10 and another well known pesticide, dichloro-diphenyl-trichloroethane (C14-H9-Cl5) should be minimal since each attacks a different, and apparently mutually exclusive, class of bugs.
Sadly, this quotation was removed from later editions of the handbook after the {suit}s took over and DEC became much more `businesslike'.

The history above is known to many old-time hackers. But there's more: Peter Samson, author of the {TMRC} lexicon, reports that he named `DDT' after a similar tool on the TX-0 computer, the direct ancestor of the PDP-1 built at MIT's Lincoln Lab in 1957. The debugger on that ground-breaking machine (the first transistorized computer) rejoiced in the name FLIT (FLexowriter Interrogation Tape).


/d*-pib'/ [from the PDP-10 instruction set] vt. To plop something down in the middle. Usage: silly. "DPB yourself into that couch there." The connotation would be that the couch is full except for one slot just big enough for you to sit in. DPB means `DePosit Byte', and was the name of a PDP-10 instruction that inserts some bits into the middle of some other bits. This usage has been kept alive by the Common LISP function of the same name.

elder days

n. The heroic age of hackerdom (roughly, pre-1980); the era of the {PDP-10}, {TECO}, {{ITS}}, and the ARPANET. This term has been rather consciously adopted from J. R. R. Tolkien's fantasy epic `The Lord of the Rings'. Compare {Iron Age}; see also {elvish}.


/eks'ch*/ or /eksch/ vt. To exchange two things, each for the other; to swap places. If you point to two people sitting down and say "Exch!", you are asking them to trade places. EXCH, meaning EXCHange, was originally the name of a PDP-10 instruction that exchanged the contents of a register and a memory location. Many newer hackers tend to be thinking instead of the {PostScript} exchange operator (which is usually written in lowercase).


n. 1. The {PDP-10} successor that was to have been built by the Super Foonly project at the Stanford Artificial Intelligence Laboratory along with a new operating system. The intention was to leapfrog from the old DEC timesharing system SAIL was running to a new generation, bypassing TENEX which at that time was the ARPANET standard. ARPA funding for both the Super Foonly and the new operating system was cut in 1974. Most of the design team went to DEC and contributed greatly to the design of the PDP-10 model KL10.

2. The name of the company formed by Dave Poole, one of the principal Super Foonly designers, and one of hackerdom's more colorful personalities. Many people remember the parrot which sat on Poole's shoulder and was a regular companion.

3. Any of the machines built by Poole's company. The first was the F-1 (a.k.a. Super Foonly), which was the computational engine used to create the graphics in the movie "TRON". The F-1 was the fastest PDP-10 ever built, but only one was ever made. The effort drained Foonly of its financial resources, and they turned towards building smaller, slower, and much less expensive machines. Unfortunately, these ran not the popular {TOPS-20} but a TENEX varient called Foonex; this seriously limited their market. Also, the machines shipped were actually wire-wrapped engineering prototypes requiring individual attention from more than usually competent site personnel, and thus had significant reliability problems. Poole's legendary temper and unwillingness to suffer fools gladly did not help matters. By the time of the Jupiter project cancellation in 1983 Foonly's proposal to build another F-1 was eclipsed by the {Mars}, and the company never quite recovered. See the {Mars} entry for the continuation and moral of this story.

Origin of the name Foonly

Comment from Joe Smith: In late 1987 I had a chance to see the D. C. Power Lab (the AI lab was named after Mr. D. C. Power; and not after an electrical term). One of the guys there was showing off the space cadet keyboards connected to the KA+KL combo. He mentioned that DEC had took their design, and the designers, and created the KL-10 as a scaled-back version of the Foonly. When asked where "Foonly" came from, the tour guide stated that when someone typed "foo" at the program, it came back with "foonly". This recollection matches this message from Edward Rice:
  From: ehrice@his.com (Edward Rice)
  Newsgroups: alt.folklore.computers,alt.sys.pdp10
  Subject: Re: PDP10 clones (was: Compuserve and the DEC-10)
  Date: Fri, 06 Oct 1995 14:04:08 -0500
  When I asked about this here recently, I received e-mail from
  rwa@cs.athabascau.ca (Ross Alexander) with the following explanation:

     It comes from the error diagnostic spat out by someone's pdp10
     assembler; if you said "foo" to it, it would say "foo: nli"
     (not legal instruction).  This became a sort of mantra.

  As part of a small group that makes jokes about "inpitUL" (pronounced
  "in-pi-TUHL" and which stands for "is not presently in the User List"), I
  find this entirely plausible.


/hak'mem/ n. MIT AI Memo 239 (February 1972). A legendary collection of neat mathematical and programming hacks contributed by many people at MIT and elsewhere. (The title of the memo really is "HAKMEM", which is a 6-letterism for `hacks memo'.) Some of them are very useful techniques, powerful theorems, or interesting unsolved problems, but most fall into the category of mathematical and computer trivia. Here is a sampling of the entries (with authors), slightly paraphrased:

Item 41 (Gene Salamin): There are exactly 23,000 prime numbers less than 2^18.

Item 46 (Rich Schroeppel): The most *probable* suit distribution in bridge hands is 4-4-3-2, as compared to 4-3-3-3, which is the most *evenly* distributed. This is because the world likes to have unequal numbers: a thermodynamic effect saying things will not be in the state of lowest energy, but in the state of lowest disordered energy.

Item 81 (Rich Schroeppel): Count the magic squares of order 5 (that is, all the 5-by-5 arrangements of the numbers from 1 to 25 such that all rows, columns, and diagonals add up to the same number). There are about 320 million, not counting those that differ only by rotation and reflection.

Item 154 (Bill Gosper): The myth that any given programming language is machine independent is easily exploded by computing the sum of powers of 2. If the result loops with period = 1 with sign +, you are on a sign-magnitude machine. If the result loops with period = 1 at -1, you are on a twos-complement machine. If the result loops with period greater than 1, including the beginning, you are on a ones-complement machine. If the result loops with period greater than 1, not including the beginning, your machine isn't binary --- the pattern should tell you the base. If you run out of memory, you are on a string or bignum system. If arithmetic overflow is a fatal error, some fascist pig with a read-only mind is trying to enforce machine independence. But the very ability to trap overflow is machine dependent. By this strategy, consider the universe, or, more precisely, algebra: Let X = the sum of many powers of 2 = ...111111. Now add X to itself: X + X = ...111110 Thus, 2X = X - 1, so X = -1. Therefore algebra is run on a machine (the universe) that is two's-complement.

Item 174 (Bill Gosper and Stuart Nelson): 21963283741 is the only number such that if you represent it on the {PDP-10} as both an integer and a floating-point number, the bit patterns of the two representations are identical.

Item 176 (Gosper): The "banana phenomenon" was encountered when processing a character string by taking the last 3 letters typed out, searching for a random occurrence of that sequence in the text, taking the letter following that occurrence, typing it out, and iterating. This ensures that every 4-letter string output occurs in the original. The program typed BANANANANANANANA.... We note an ambiguity in the phrase, "the Nth occurrence of." In one sense, there are five 00's in 0000000000; in another, there are nine. The editing program TECO finds five. Thus it finds only the first ANA in BANANA, and is thus obligated to type N next. By Murphy's Law, there is but one NAN, thus forcing A, and thus a loop. An option to find overlapped instances would be useful, although it would require backing up N - 1 characters before seeking the next N-character string.

Note: This last item refers to a {Dissociated Press} implementation. See also {banana problem}.

HAKMEM also contains some rather more complicated mathematical and technical items, but these examples show some of its fun flavor.

high moby

/hi:' mohb'ee/ n. The high half of a 512K {PDP-10}'s physical address space; the other half was of course the low moby. This usage has been generalized in a way that has outlasted the {PDP-10}; for example, at the 1990 Washington D.C. Area Science Fiction Conclave (Disclave), when a miscommunication resulted in two separate wakes being held in commemoration of the shutdown of MIT's last {{ITS}} machines, the one on the upper floor was dubbed the `high moby' and the other the `low moby'. All parties involved {grok}ked this instantly. See {moby}.


/I-T-S/ n. 1. Incompatible Time-sharing System, an influential but highly idiosyncratic operating system written for PDP-6s and PDP-10s at MIT and long used at the MIT AI Lab. Much AI-hacker jargon derives from ITS folklore, and to have been `an ITS hacker' qualifies one instantly as an old-timer of the most venerable sort. ITS pioneered many important innovations, including transparent file sharing between machines and terminal-independent I/O. After about 1982, most actual work was shifted to newer machines, with the remaining ITS boxes run essentially as a hobby and service to the hacker community. The shutdown of the lab's last ITS machine in May 1990 marked the end of an era and sent old-time hackers into mourning nationwide (see {high moby}). The Royal Institute of Technology in Sweden is maintaining one `live' ITS site at its computer museum (right next to the only TOPS-10 system still on the Internet), so ITS is still alleged to hold the record for OS in longest continuous use (however, {{WAITS}} is a credible rival for this palm).

2. A mythical image of operating-system perfection worshiped by a bizarre, fervent retro-cult of old-time hackers and ex-users (see {troglodyte}, sense 2). ITS worshipers manage somehow to continue believing that an OS maintained by assembly-language hand-hacking that supported only monocase 6-character filenames in one directory per account remains superior to today's state of commercial art (their venom against UNIX is particularly intense). See also {holy wars}, {Weenix}.


/jif'kl/, /jaf'kl/, /j*-fi'kl/ vt., obs. (alt. `jfcl') To cancel or annul something. "Why don't you jfcl that out?" The fastest do-nothing instruction on older models of the PDP-10 happened to be JFCL, which stands for "Jump if Flag set and then CLear the flag"; this does something useful, but is a very fast no-operation if no flag is specified. Geoff Goodfellow, one of the jargon-1 co-authors, has long had JFCL on the license plate of his BMW. Usage: rare except among old-time PDP-10 hackers.


/jerst/ [based on the PDP-10 jump instruction] v.,obs. To suddenly change subjects, with no intention of returning to the previous topic. Usage: rather rare except among PDP-10 diehards, and considered silly. See also {AOS}.


/l*'d*b/ [from the PDP-10 instruction set] vt. To extract from the middle. "LDB me a slice of cake, please." This usage has been kept alive by Common LISP's function of the same name. Considered silly. See also {DPB}.


n. A legendary tragic failure, the archetypal Hacker Dream Gone Wrong. Mars was the code name for a family of PDP-10 compatible computers built by Systems Concepts (now, The SC Group); the multi-processor SC-30M, the small uniprocessor SC-25M, and the never-built superprocessor SC-40M. These machines were marvels of engineering design; although not much slower than the unique {Foonly} F-1, they were physically smaller and consumed less power than the much slower DEC KS10 or Foonly F-2, F-3, or F-4 machines. They were also completely compatible with the DEC KL10, and ran all KL10 binaries, including the operating system, with no modifications at about 2--3 times faster than a KL10.

When DEC cancelled the Jupiter project in 1983, Systems Concepts should have made a bundle selling their machine into shops with a lot of software investment in PDP-10s, and in fact their spring 1984 announcement generated a great deal of excitement in the PDP-10 world. TOPS-10 was running on the Mars by the summer of 1984, and TOPS-20 by early fall. Unfortunately, the hackers running Systems Concepts were much better at designing machines than in mass producing or selling them; the company allowed itself to be sidetracked by a bout of perfectionism into continually improving the design, and lost credibility as delivery dates continued to slip. They also overpriced the product ridiculously; they believed they were competing with the KL10 and VAX 8600 and failed to reckon with the likes of Sun Microsystems and other hungry startups building workstations with power comparable to the KL10 at a fraction of the price. By the time SC shipped the first SC-30M to Stanford in late 1985, most customers had already made the traumatic decision to abandon the PDP-10, usually for VMS or UNIX boxes. Most of the Mars computers built ended up being purchased by CompuServe.

This tale and the related saga of Foonly hold a lesson for hackers: if you want to play in the Real World, you need to learn Real World moves.


/moh'bee/ [MIT: seems to have been in use among model railroad fans years ago. Derived from Melville's `Moby Dick' (some say from `Moby Pickle').] 1. adj. Large, immense, complex, impressive. "A Saturn V rocket is a truly moby frob." "Some MIT undergrads pulled off a moby hack at the Harvard-Yale game." (See appendix A).
2. n. obs. The maximum address space of a machine (see below). For a 680[234]0 or VAX or most modern 32-bit architectures, it is 4,294,967,296 8-bit bytes (4 gigabytes).
3. A title of address (never of third-person reference), usually used to show admiration, respect, and/or friendliness to a competent hacker. "Greetings, moby Dave. How's that address-book thing for the Mac going?"
4. adj. In backgammon, doubles on the dice, as in `moby sixes', `moby ones', etc. Compare this with {bignum} (sense 2): double sixes are both bignums and moby sixes, but moby ones are not bignums (the use of `moby' to describe double ones is sarcastic). Standard emphatic forms: `Moby foo', `moby win', `moby loss'. `Foby moo': a spoonerism due to Richard Greenblatt.

This term entered hackerdom with the Fabritek 256K memory added to the MIT AI PDP-6 machine, which was considered unimaginably huge when it was installed in the 1960s (at a time when a more typical memory size for a timesharing system was 72 kilobytes). Thus, a moby is classically 256K 36-bit words, the size of a PDP-6 or PDP-10 moby. Back when address registers were narrow the term was more generally useful, because when a computer had virtual memory mapping, it might actually have more physical memory attached to it than any one program could access directly. One could then say "This computer has 6 mobies" meaning that the ratio of physical memory to address space is 6, without having to say specifically how much memory there actually is. That in turn implied that the computer could timeshare six `full-sized' programs without having to swap programs between memory and disk.

Nowadays the low cost of processor logic means that address spaces are usually larger than the most physical memory you can cram onto a machine, so most systems have much *less* than one theoretical `native' moby of core. Also, more modern memory-management techniques (esp. paging) make the `moby count' less significant. However, there is one series of popular chips for which the term could stand to be revived --- the Intel 8088 and 80286 with their incredibly {brain-damaged} segmented-memory designs. On these, a `moby' would be the 1-megabyte address span of a segment/offset pair (by coincidence, a PDP-10 moby was exactly 1 megabyte of 9-bit bytes).


[Programmed Data Processor model 10] n. The machine that made timesharing real. It looms large in hacker folklore because of its adoption in the mid-1970s by many university computing facilities and research labs, including the MIT AI Lab, Stanford, and CMU. Some aspects of the instruction set (most notably the bit-field instructions) are still considered unsurpassed. The 10 was eventually eclipsed by the VAX machines (descendants of the PDP-11) when DEC recognized that the 10 and VAX product lines were competing with each other and decided to concentrate its software development effort on the more profitable VAX. The machine was finally dropped from DEC's line in 1983, following the failure of the Jupiter Project at DEC to build a viable new model. (Some attempts by other companies to market clones came to nothing; see {Foonly}) This event spelled the doom of {{ITS}} and the technical cultures that had spawned the original Jargon File, but by mid-1991 it had become something of a badge of honorable old-timerhood among hackers to have cut one's teeth on a PDP-10. See {{TOPS-10}}, {{ITS}}, {AOS}, {BLT}, {DDT}, {DPB}, {EXCH}, {HAKMEM}, {JFCL}, {LDB}, {pop}, {push}.


n. The most famous computer that never was. {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} were labeled `DECSYSTEM-20' (the block capitals being the result of a lawsuit brought against DEC by Singer, which once made a computer called `system-10'), but contrary to popular lore there was never a `PDP-20'; the only difference between a 10 and a 20 was the operating system and the color of the paint. Most (but not all) machines sold to run TOPS-10 were painted `Basil Blue', whereas most TOPS-20 machines were painted `DEC TerraCotta' (not `Chinese Red', and often mistakenly called orange).


/pip/ [Peripheral Interchange Program] vt.,obs. To copy; from the program PIP on CP/M, RSX-11, RSTS/E, and OS/8 (derived from a utility on the PDP-6) that was used for file copying (and in OS/8 and RT-11 for just about every other file operation you might want to do). It is said that when the program was originated, during the development of the PDP-6 in 1963, it was called ATLATL (`Anything, Lord, to Anything, Lord').


/pop'J/ [from a {PDP-10} return-from-subroutine instruction] n.,v. To return from a digression. By verb doubling, "Popj, popj" means roughly "Now let's see, where were we?" See {RTI}.


/P-P-N/, /pip'n/ [from `Project-Programmer Number'] n. A user-ID under {{TOPS-10}} and its various mutant progeny at SAIL, BBN, CompuServe, and elsewhere. Old-time hackers from the PDP-10 era sometimes use this to refer to user IDs on other systems as well.


[from the operation that puts the current information on a stack, and the fact that procedure return addresses are saved on a stack] Also PUSH /push/ or PUSHJ /push'J/ (the latter based on the PDP-10 procedure call instruction). 1. To put something onto a {stack} or {pdl}. If one says that something has been pushed onto one's stack, it means that the Damoclean list of things hanging over ones's head has grown longer and heavier yet. This may also imply that one will deal with it *before* other pending items; otherwise one might say that the thing was `added to my queue'.

2. vi. To enter upon a digression, to save the current discussion for later. Antonym of {pop}; see also {stack}, {pdl}.


n.,obs. /S-O-S/ 1. An infamously {losing} text editor. Once, back in the 1960s, when a text editor was needed for the PDP-6, a hacker crufted together a {quick-and-dirty} `stopgap editor' to be used until a better one was written. Unfortunately, the old one was never really discarded when new ones (in particular, {TECO}) came along. SOS is a descendant (`Son of Stopgap') of that editor, and many PDP-10 users gained the dubious pleasure of its acquaintance. Since then other programs similar in style to SOS have been written, notably the early font editor BILOS /bye'lohs/, the Brother-In-Law Of Stopgap (the alternate expansion `Bastard Issue, Loins of Stopgap' has been proposed).
2. /sos/ n. To decrease; inverse of {AOS}, from the PDP-10 instruction set.


/tops-ten/ n. DEC's proprietary OS for the fabled {PDP-10} machines, long a favorite of hackers but now effectively extinct. A fountain of hacker folklore. See also {{ITS}}, {{TOPS-20}}, {{TWENEX}}, {VMS}, {operating system}. TOPS-10 was sometimes called BOTS-10 (from `bottoms-ten') as a comment on the inappropriateness of describing it as the top of anything.


/tops-twen'tee/ n. See {{TWENEX}}.


/twe'neks/ n. The TOPS-20 operating system by DEC --- the second proprietary OS for the PDP-10 --- preferred by most PDP-10 hackers over TOPS-10 (that is, by those who were not {{ITS}} or {{WAITS}} partisans). TOPS-20 began in 1969 as Bolt, Beranek & Newman's TENEX operating system using special paging hardware. By the early 1970s, almost all of the systems on the ARPANET ran TENEX. DEC purchased the rights to TENEX from BBN and began work to make it their own. The first in-house code name for the operating system was VIROS (VIRtual memory Operating System); when customers started asking questions, the name was changed to SNARK so DEC could truthfully deny that there was any project called VIROS. When the name SNARK became known, the name was briefly reversed to become KRANS; this was quickly abandoned when it was discovered that `krans' meant `funeral shroud' in Swedish. Ultimately DEC picked TOPS-20 as the name of the operating system, and it was as TOPS-20 that it was marketed. The hacker community, mindful of its origins, quickly dubbed it {{TWENEX}} (a contraction of `twenty TENEX'), even though by this point very little of the original TENEX code remained (analogously to the differences between AT&T V6 UNIX and BSD). DEC people cringed when they heard "TWENEX", but the term caught on nevertheless (the written abbreviation `20x' was also used). TWENEX was successful and very popular; in fact, there was a period in the early 1980s when it commanded as fervent a culture of partisans as UNIX or ITS --- but DEC's decision to scrap all the internal rivals to the VAX architecture and its relatively stodgy VMS OS killed the DEC-20 and put a sad end to TWENEX's brief day in the sun. DEC attempted to convince TOPS-20 hackers to convert to {VMS}, but instead, by the late 1980s, most of the TOPS-20 hackers had migrated to UNIX.

Preface - A little song - ADVENT - AOS - BLT - connector conspiracy - DDT - DPB - elder days - EXCH - Foonly - HAKMEM - high moby - ITS - JFCL - JRST - LDB - Mars - moby - PDP-10 - PDP-20 - PIP - POPJ - PPN - push - SOS - TOPS-10 - TOPS-20 - TWENEX

Up to the index for PDP-10 page.
Maintained by Joe Smith at js-cgi@inwap.com