:drop-outs: n. 1. A variety of `power glitch' (see {glitch}); momentary 0 voltage on the electrical mains. 2. Missing characters in typed input due to software malfunction or system saturation (this can happen under UNIX when a bad connection to a modem swamps the processor with spurious character interrupts). 3. Mental glitches; used as a way of describing those occasions when the mind just seems to shut down for a couple of beats. See {glitch}, {fried}.
:drugged: adj. (also `on drugs') 1. Conspicuously stupid, heading toward {brain-damaged}. Often accompanied by a pantomime of toking a joint (but see {appendix B}). 2. Of hardware, very slow relative to normal performance.
:drum: adj,n. Ancient techspeak term referring to slow,
cylindrical magnetic media which were once state-of-the-art
mass-storage devices. Under BSD UNIX the disk partition used for
swapping is still called `/dev/drum'; this has led to
considerable humor and not a few straight-faced but utterly bogus
`explanations' getting foisted on {newbie}s. See also "{The
Story of Mel, a Real Programmer}" in {appendix A}.
:drunk mouse syndrome: (also `mouse on drugs') n. A malady
exhibited by the mouse pointing device of some computers. The
typical symptom is for the mouse cursor on the screen to move in
random directions and not in sync with the motion of the actual
mouse. Can usually be corrected by unplugging the mouse and
plugging it back again. Another recommended fix for optical mice
is to rotate your mouse pad 90 degrees.
At Xerox PARC in the 1970s, most people kept a can of copier cleaner (isopropyl alcohol) at their desks. When the steel ball on the mouse had picked up enough {cruft} to be unreliable, the mouse was doused in cleaner, which restored it for a while. However, this operation left a fine residue that accelerated the accumulation of cruft, so the dousings became more and more frequent. Finally, the mouse was declared `alcoholic' and sent to the clinic to be dried out in a CFC ultrasonic bath.
:Duff's device: n. The most dramatic use yet seen of {fall through} in C, invented by Tom Duff when he was at Lucasfilm. Trying to {bum} all the instructions he could out of an inner loop that copied data serially onto an output port, he decided to {unroll} it. He then realized that the unrolled version could be implemented by *interlacing* the structures of a switch and a loop:
register n = (count + 7) / 8; /* count > 0 assumed */
switch (count % 8)
{
case 0: do { *to = *from++;
case 7: *to = *from++;
case 6: *to = *from++;
case 5: *to = *from++;
case 4: *to = *from++;
case 3: *to = *from++;
case 2: *to = *from++;
case 1: *to = *from++;
} while (—n > 0);
}
Having verified that the device is valid portable C, Duff announced it. C's default {fall through} in case statements has long been its most controversial single feature; Duff observed that "This code forms some sort of argument in that debate, but I'm not sure whether it's for or against."
:dumb terminal: n. A terminal which is one step above a {glass tty}, having a minimally-addressable cursor but no on-screen editing or other features which are claimed by a {smart terminal}. Once upon a time, when glass ttys were common and addressable cursors were something special, what is now called a dumb terminal could pass for a smart terminal.