info-mac@uw-beaver (info-mac) (11/10/84)
From: Richard Garland <OC.GARLAND%CU20B@COLUMBIA.ARPA>
There was a question on the response MACTerminal gives to a host's
inquiry. There is a confusion here. There are 2 kinds of questions
that can be asked of the terminal, and 2 responses.
o The "Answerback message" is a remnant from teletype days
when systems would call up terminals (like news service
terminals) and ask for an ID. The system sends the ASCII
"ENQ" (<CTRL>-E) to get this response. On a VT100 you can
put this message in while in set up mode. It is generally
not used by time sharing systems. I usually put my Dept.
name in, since a thief probably wouldn't know how to reset
it (or invoke it). I only see it when I type some garbage
by mistake and by chance a ^E comes by and the terminal sends
back the ol' answerback message. It is also sent by a VT100
in response to a "long break" (SHIFT-BREAK on the VT100).
o The "Device Attributes" or "What are you". This identifies
the configuration of the terminal. For Old style (i.e. VT52)
DEC terminals it was invoked by "<ESC>Z" to which a VT52 would
respond "<ESC>/Z". For a VT100 it is invoked by the ANSI DA
(Device attributes) sequence "<ESC>[c" or "<ESC>[0c"" (the "0" is
optional). According to the VT100 User's Guide the terminaal
responds with the sequence "<ESC>[?l;Psc" Where "Ps" is a number
between 0 and 7 giving what options are present (i.e. AVO, graphics
etc.) The sequence mentions in the question to this news group:
"<ESC>[E;V" does not fit this pattern so either Macterminal
has its own ideas of ANSI sequences or the questioner may
have made a typo.
Rg
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