[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).
[glossary]
[Reference(s) to this entry by made by: {backgammon}{bignum}{gonzo}{high moby}{monty}{vaxocentrism}]