WhatIs

/mä-lē-gärd/

[University of Illinois]

n. A shield to prevent tripping of some Big Red Switch by clumsy or ignorant hands. Originally used of some plexiglass covers improvised for the BRS on an IBM 4341 after a programmer's toddler daughter (named Molly) frobbed it twice in one day. Later generalized to covers over stop/reset switches on disk drives and networking equipment.

/mä-jə-lō/

prep. Except for. From mathematical terminology; one can consider saying that 4 = 22 except for the 9s (4 = 22 mod 9).

"Well, LISP seems to work okay now, modulo that GC bug."

"I feel fine today modulo a slight headache."

/mä-jə-lər ek-spə-nen(t)-shē-ā-shən/

raising an integer to the power of another integer, modulo some integer. For integers a, n, and m, am mod n.

For example, 53 mod 100 = 25.

Modular exponentiation can be done fairly quickly with a sequence of bit shifts and adds, and special purpose chips have been designed.

See also discrete logarithm problem.

/mōd bit/

n. A flag, usually in hardware, that selects between two (usually quite different) modes of operation. The connotations are different from flag bit in that mode bits are mainly written during a boot or set-up phase, are seldom explicitly read, and seldom change over the lifetime of an ordinary program. The classic example was the EBCDIC-vs.-ASCII bit (#12) of the Program Status Word of the IBM 360. Another was the bit on a PDP-12 that controlled whether it ran the PDP-8 or the LINC instruction set.

/mōd/

n. A general state, usually used with an adjective describing the state. Use of the word 'mode' rather than 'state' implies that the state is extended over time, and probably also that some activity characteristic of that state is being carried out.

"No time to hack; I'm in thesis mode."

/mäd/

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.

/mō-bē/

[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."

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).

/mis-wȯrt/

[from wart by analogy with misbug]

/mis'd'əm fīv/

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.

/mis-fē-chər/

n. A feature that eventually causes lossage, possibly because it is not adequate for a new situation which has evolved. It is not the same as a bug, because fixing it involves a substantial philosophical change to the structure of the system involved. A misfeature is different from a simple unforeseen side effect; the term implies that the misfeature was actually carefully planned to be that way, but its future consequences or circumstances just weren't predicted accurately. This is different from just not having thought ahead about it at all.