moby

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').] 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 "{The Meaning of `Hack'}").
   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).