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question about terminal modes
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yawnmoth
Dec 10, 2009, 2:35:00 PM12/10/09
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PuTTY uses two terminal modes - VERASE, which it sets to 0x7F, and
TTY_OP_OSPEED, which it sets to 0x9600. For VERASE, my question is
why 0x7F? Why not 0x61 (ie. the letter 'a')? Sure, the letter 'a'
could occur on its own in the output but couldn't the same be said for
0x7F as well? Or is 0x7F not a character terminals are allowed to
print? If so what other characters are terminals not allowed to
print? Anything larger than 0x7F? Does it depend on the TERM
environmental variable? PuTTY uses xterm and the SSH specs use, in
their example, vt100. Does it make a difference?
TTY_OP_OSPEED, which it sets to 0x9600. For VERASE, my question is
why 0x7F? Why not 0x61 (ie. the letter 'a')? Sure, the letter 'a'
could occur on its own in the output but couldn't the same be said for
0x7F as well? Or is 0x7F not a character terminals are allowed to
print? If so what other characters are terminals not allowed to
print? Anything larger than 0x7F? Does it depend on the TERM
environmental variable? PuTTY uses xterm and the SSH specs use, in
their example, vt100. Does it make a difference?
Also, I'm not sure what TTY_OP_OSPEED does. Does setting that mean
that the server will only send you 38,400 bits per second? If so, why
not up it to 0xFFFF or 0xFFFFFFFF bits per second? SFTP doesn't have
speed limits so why do terminals need them?
yawnmoth
Dec 10, 2009, 5:19:39 PM12/10/09
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According to <http://asciitable.com/>, 0x7F corresponds to "Del" so I
guess that's one question I don't need an answer to...
Jacob Nevins
Dec 10, 2009, 6:41:16 PM12/10/09
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yawnmoth <terr...@yahoo.com> writes:
>I'm not sure what TTY_OP_OSPEED does. Does setting that mean
>that the server will only send you 38,400 bits per second? If so, why
>not up it to 0xFFFF or 0xFFFFFFFF bits per second? SFTP doesn't have
>speed limits so why do terminals need them?
>I'm not sure what TTY_OP_OSPEED does. Does setting that mean
>that the server will only send you 38,400 bits per second? If so, why
>not up it to 0xFFFF or 0xFFFFFFFF bits per second? SFTP doesn't have
>speed limits so why do terminals need them?
This is covered by
<http://the.earth.li/~sgtatham/putty/0.60/htmldoc/Chapter4.html#config-termspeed>.
It's mostly historical; it has little effect on most servers, and
servers don't directly limit the speed at which they send data based on
it.
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