 2 definitions found
From Jargon File (4.3.1, 29 Jun 2001) [jargon]:
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. adjective 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. adjective 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 (27 SEP 03) [foldoc]:
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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