:misfeature: /mis-fee'chr/ or /mis'fee`chr/ /n./ A feature that eventually causes lossage, possibly because it is not adequate for a new situation that has evolved. Since it results from a deliberate and properly implemented feature, a misfeature is not a bug. Nor is it a simple unforeseen side effect; the term implies that the feature in question was carefully planned, but its long-term consequences were not accurately or adequately predicted (which is quite different from not having thought ahead at all). A misfeature can be a particularly stubborn problem to resolve, because fixing it usually involves a substantial philosophical change to the structure of the system involved.

Many misfeatures (especially in user-interface design) arise because the designers/implementors mistake their personal tastes for laws of nature. Often a former feature becomes a misfeature because trade-offs were made whose parameters subsequently change (possibly only in the judgment of the implementors). "Well, yeah, it is kind of a misfeature that file names are limited to six characters, but the original implementors wanted to save directory space and we're stuck with it for now."

:Missed'em-five: /n./ Pejorative hackerism for AT&T System V
Unix, generally used by {BSD} partisans in a bigoted mood. (The
synonym `SysVile' is also encountered.) See {software bloat},
{Berzerkeley}.

:missile address: /n./ See {ICBM address}.

:miswart: /mis-wort/ /n./ [from {wart} by analogy with {misbug}] A {feature} that superficially appears to be a {wart} but has been determined to be the {Right Thing}. For example, in some versions of the {EMACS} text editor, the `transpose characters' command exchanges the character under the cursor with the one before it on the screen, *except* when the cursor is at the end of a line, in which case the two characters before the cursor are exchanged. While this behavior is perhaps surprising, and certainly inconsistent, it has been found through extensive experimentation to be what most users want. This feature is a miswart.

: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).

:mockingbird: /n./ Software that intercepts communications (especially login transactions) between users and hosts and provides system-like responses to the users while saving their responses (especially account IDs and passwords). A special case of {Trojan horse}.

:mod: /vt.,n./ 1. Short for `modify' or `modification'. Very commonly used — in fact the full terms are considered markers that one is being formal. The plural `mods' is used esp. with reference to bug fixes or minor design changes in hardware or software, most esp. with respect to {patch} sets or a {diff}. 2. Short for {modulo} but used *only* for its techspeak sense.