PCjr Telnet Server Test

On 14 Sep 2008 at 11:49, Michael B. Brutman wrote: Depends on the vintage of the implementation. BS originally was just that--move the current printing/display position one back, erasing nothing. 127 (Rubout/ASCII DEL) was used as a delete character because it punched all the holes in a tape and was ignored on printing as a fill character. (Many of us can still remember editing paper tape using rubouts to delete previously punched characters). The non-erasing interpretation of BS came as a surprise to me when writing early text CRT terminal firmware. To form various international characters, the client could send out the character for an ogonek, then a BS, then, say, an A. The firmware had to display the ogonek, move the cursor back a space, then combine the ogonek with the A and display the ogonek-inflected-A. The reverse sequence (A-BS-ogonek) also had to be honored. The purpose of this was to be compatible with earlier printing terminals. WikiP has the following on BS: "The ambiguity surrounding Backspace comes from mismatches between the intent of the human or software transmitting the Backspace and the interpretation by the software receiving it. If the transmitter expects Backspace to erase the previous character and the receiver expects Delete to be used to erase the previous character, many receivers will echo the Backspace as "^H", just as they would echo any other uninterpreted control character. (A similar mismatch in the other direction may yield Delete displayed as "^?".)" So, it's your posion. I've used telnet servers that insist on RO to erase characters and print ^H when backspace is received. OTOH, the current Linux telnet server treats BS and DEL identically--and if I were in your shoes, I'd do the same. Cheers, Chuck