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2 definitions found
 for moby
From The Jargon File (version 4.4.7, 29 Dec 2003) :

  moby
   /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?). Now
      common.]
  
      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 for discussion.)
  
      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 3): 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.
  
      5. The largest available unit of something which is available in discrete
      increments. Thus, ordering a ?moby Coke? at the local fast-food joint is
      not just a request for a large Coke, it's an explicit request for the
      largest size they sell.
  
      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 widely-used
      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).
  

From The Free On-line Dictionary of Computing (30 December 2018) :

  moby
  
      /moh'bee/ (From 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. 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."
  
     2. (Obsolete) The maximum address space of a computer (see
     below).  For a 680[234]0 or VAX or most modern 32-bit
     architectures, it is 4,294,967,296 8-bit bytes (four
     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. In backgammon, doubles on the dice, as in "moby sixes",
     "moby ones", etc.  Compare this with bignum: double sixes
     are both bignums and moby sixes, but moby ones are not bignums
     (the use of "moby" to describe double ones is sarcastic).
  
     5. The largest available unit of something which is available
     in discrete increments.  Thus a "moby Coke" is not just large,
     it's the largest size on sale.
  
     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 time-sharing
     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 six mobies" meaning that the ratio of
     physical memory to address space is six, 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 (especially paging) make the
     "moby count" less significant.  However, there is one series
     of widely-used 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 one megabyte of
     nine-bit bytes).
  
     [{Jargon File]
  
     (1997-10-01)
  

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