Re:Vim's 25th anniversary and the release of Vim 8
by kps on Thursday February 09, 2017 @12:30PM
(#13608815)
For the reason DEL is shifted ‘_’, see your friendly neighbourhood ASCII table, and/or one of the recent HN threads¹. The ADM-3A² is a good example of a bit-paired keyboard³.
¹ https://news.ycombinator.com/item?id=13539552
RUB. When the RUB (rubout) key is typed while holding down the SHIFT key, a non-displayable rubout code (ASCII DEL) is transmitted to the computer. The cursor is not advanced and the character code stored in display memory is not overwritten. RUB is normally used to tell the computer that a previous character should be deleted.
HERE IS. If the Answer Back option is installed, typing this key transmits an identification message (stored in a special ADM-3A memory) that identifies the terminal and alerts the host computer that a message is to follow. If no Answer Back option is installed, the key has no function.
[0] http://www.classiccmp.org/dunfield/altair/d/adm3a.pdf