The term {software rot} is almost synonymous. Software rot is the effect, bit rot the notional cause.
:bit twiddling: /n./ 1. (pejorative) An exercise in tuning (see {tune}) in which incredible amounts of time and effort go to produce little noticeable improvement, often with the result that the code becomes incomprehensible. 2. Aimless small modification to a program, esp. for some pointless goal. 3. Approx. syn. for {bit bashing}; esp. used for the act of frobbing the device control register of a peripheral in an attempt to get it back to a known state.
:bit-paired keyboard: /n./ obs. (alt. `bit-shift keyboard') A non-standard keyboard layout that seems to have originated with the Teletype ASR-33 and remained common for several years on early computer equipment. The ASR-33 was a mechanical device (see {EOU}), so the only way to generate the character codes from keystrokes was by some physical linkage. The design of the ASR-33 assigned each character key a basic pattern that could be modified by flipping bits if the SHIFT or the CTRL key was pressed. In order to avoid making the thing more of a Rube Goldberg kluge than it already was, the design had to group characters that shared the same basic bit pattern on one key.
Looking at the ASCII chart, we find:
high low bits
bits 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001
010 ! " # $ % & ' ( )
011 0 1 2 3 4 5 6 7 8 9
This is why the characters !"#$%&'() appear where they do on a Teletype (thankfully, they didn't use shift-0 for space). This was *not* the weirdest variant of the {QWERTY} layout widely seen, by the way; that prize should probably go to one of several (differing) arrangements on IBM's even clunkier 026 and 029 card punches.
When electronic terminals became popular, in the early 1970s, there was no agreement in the industry over how the keyboards should be laid out. Some vendors opted to emulate the Teletype keyboard, while others used the flexibility of electronic circuitry to make their product look like an office typewriter. These alternatives became known as `bit-paired' and `typewriter-paired' keyboards. To a hacker, the bit-paired keyboard seemed far more logical — and because most hackers in those days had never learned to touch-type, there was little pressure from the pioneering users to adapt keyboards to the typewriter standard.
The doom of the bit-paired keyboard was the large-scale introduction of the computer terminal into the normal office environment, where out-and-out technophobes were expected to use the equipment. The `typewriter-paired' standard became universal, `bit-paired' hardware was quickly junked or relegated to dusty corners, and both terms passed into disuse.
:bitblt: /bit'blit/ /n./ [from {BLT}, q.v.] 1. Any of a family of closely related algorithms for moving and copying rectangles of bits between main and display memory on a bit-mapped device, or between two areas of either main or display memory (the requirement to do the {Right Thing} in the case of overlapping source and destination rectangles is what makes BitBlt tricky). 2. Synonym for {blit} or {BLT}. Both uses are borderline techspeak.
:BITNET: /bit'net/ /n./ [acronym: Because It's Time NETwork] Everybody's least favorite piece of the network (see {network, the}). The BITNET hosts are a collection of IBM dinosaurs and VAXen (the latter with lobotomized comm hardware) that communicate using 80-character {{EBCDIC}} card images (see {eighty-column mind}); thus, they tend to mangle the headers and text of third-party traffic from the rest of the ASCII/{RFC}-822 world with annoying regularity. BITNET was also notorious as the apparent home of {B1FF}.