Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!ptsfa!ames!sdcsvax!ucbvax!YALE.ARPA!LEICHTER-JERRY From: LEICHTER-JERRY@YALE.ARPA.UUCP Newsgroups: comp.os.vms Subject: Re: SET TERMINAL/MESS_UP_SETTINGS Message-ID: <8706182012.AA06103@ucbvax.Berkeley.EDU> Date: Thu, 18-Jun-87 16:13:17 EDT Article-I.D.: ucbvax.8706182012.AA06103 Posted: Thu Jun 18 16:13:17 1987 Date-Received: Sat, 20-Jun-87 06:36:16 EDT Sender: daemon@ucbvax.BERKELEY.EDU Reply-To: Distribution: world Organization: The ARPA Internet Lines: 44 I was recently surprised to discover if a VT240 is set for "VT100 mode, VT240 ID," the command $ SET TERMINAL/INQUIRE will change it to "VT200 mode, 7-bit controls." The analogous thing happens on a VT220. Did it always do this, or is this a VMS 4.5 innovation? Should I be irritated by this, and, if not, why not? It's been doing this since SET TERM/INQUIRE was invented (V4.0). It does this is that, having received an ID from the terminal saying "I'm a VT240", it is going to set up the various terminal characteristics to say "there's a device out there with (for example) ANSI_CRT DEC_CRT DEC_CRT2". Program are supposed to rely on these characteristics, not on particular terminal types - back in the "good old days", there were tons of programs that ran on VT100's but would fail on (functionally identical) VT102's, since they looked at the exact device type. Given that the terminal will be marked as having VT240 attributes, it had better respond to VT240 controls - which it will NOT do while in VT100 mode. So SET TERMINAL makes sure the terminal is set up to agree with the recorded characteristics - just as SET TERM/WIDTH:132 sends an escape sequence to actually switch the terminal to 132-column mode. If you want your terminal to really look like a VT100 - only necessary for old programs that rely on terminal types, not the encoded attributes - set the terminal to "VT100 mode, VT100 ID" - that's exactly why that setting was created. -- Jerry (BTW, the reason for the "7-bit controls" is a bit more subtle, and essential- ly a temporary work-around: The RTL SMG input routines don't work with 8-bit controls. The problem is that in 8-bit mode, there are TWO encodings for many things - e.g., either CSI or ESC [ is acceptable as a command sequence introducer. The SMG TERMTABLE facility has no way to specify such synonyms. In 7-bit control mode, the terminal will always use the 7-bit representation, and the problem goes away. Note however that this only affects what represen- tation the terminal will use when sending to the host - if the comm line pro- vides an 8-bit path, you can use either representation when sending stuff to the terminal.) -------