[derefr]

> You could print a line in bold, for instance, by issuing a CR without an LF and then printing the same line again.

True, but mildly redundant: "overprinting" was explicitly the purpose of 0x08 backspace (which had nothing, originally, to do with 0x7F deletion.)

[jff]

To overprint a whole line using 0x08, you'd need one 0x08 for each character in the line. So an N-character line overprinted that way would take N3 characters in memory.

Using CR, you'd need N2 + 1 characters.

[mzs]

I had a daisey wheel printer in the late '80s that had a few characters of buffer. I had to know that it took quite some time for every CR. It would do the niave bold of the full line with CR, but if it got X^HX it would hit the X and then slide the head over a bit to the right to smear and get the bold effect, which looked much better. It was not uncommon and that's another reason a lot code did it the BS way for OS capable HC devices.

[jff]

Ugh, wish I had checked this after sending it, now it's too late to edit. I think the gist of it is clear, but to make sure:

Overprinted with 0x08: requires 3N characters

Overprinted with CR: requires 2N+1 characters

[Someone]

Even ignoring additional time needed to send those extra characters, it also was a lot faster than those control-H's, and (I guess) caused way less wear on your printer.

[derefr]

That presumes you're going like A^HAB^HB; you could just emit foo, and then strlen(foo) ^Hs.

[wtallis]

I wonder how precise the backspacing was - how many times could you print a character and backspace before the head had drifted by a full point?