templon@silver.bacs.indiana.edu (jeffrey templon) (03/11/89)
What a hairball! OK, I have looked in the TERMS. file, in the VMSXXX files, and the manual. I tried looking in the termcap file - hence the word, "hairball." The editor - GNU Emacs 18.52. Vax/VMS 4.6. I have two problems: first is that there is no termcap entry for a VT131. Can someone send me one? I have *no* desire to learn how to do this if someone else already has. Second problem: I got around (temporarily) this problem by setting the VT131 to VT100 (i.e. SET TERM/VT100). This allows me to use the emacs, but whenever the screen scrolls, I get this horrible mess in the minibuffer: Failing I-search:^S^S^S^Q- Once I got Failing regexp I-search: OB^S^Q- this was when the scroll resulted in the end-of-text moving onto the screen. I have searched through the VMS SET TERM docs and have seen some stuff about the system sending c-s and c-q to regulate flow control, but i didn't understand it. I should point out that the terminal line runs through a GANDALF multiplexer before getting to the terminal, I don't know if that does anything with control chars. Final problem (yeah, I know I only said two): I can't get control-S! VMS uses control-s to tell the process "stop sending data, you ugly beast." So when I type c-x c-s, emacs just sits there forever, waiting for me to type control-q so it can send data again. Someone must have dealt with this already.... help! I should note in closing that when I use emacs using my mac running versaterm thru a modem and a LATserver to the VAX, I don't have this failing I-search mung. I still have the control-S problem though. jt
phd_ivo@gsbacd.uchicago.edu (03/12/89)
>Second problem: I got around (temporarily) this problem by setting the VT131 >to VT100 (i.e. SET TERM/VT100). This allows me to use the emacs, but whenever >the screen scrolls, I get this horrible mess in the minibuffer: > >Failing I-search:^S^S^S^Q- > >Once I got Failing regexp I-search: OB^S^Q- >... I should >point out that the terminal line runs through a GANDALF multiplexer before >getting to the terminal, I don't know if that does anything with control chars. > >Final problem (yeah, I know I only said two): I can't get control-S! VMS >uses control-s to tell the process "stop sending data, you ugly beast." So >when I type c-x c-s, emacs just sits there forever, waiting for me to type >control-q so it can send data again. > I am neither a GNU, nor a VMS expert. In addition, we are running an old version of GNU emacs here. However, your symptoms look familiar to me. ^S and ^Q were two unfortunate choices for control character usage, since it just asks for all sort of problems. First, we run an ethernet server here, and when I want to make it pass ^S ^Q through to the terminal (yes our server traps it; switch off with "set flow disabled"), and I resume my session, I get a ^S ^Q sequence passed to my process, resulting in emacs waiting for a quoted search. Second, at least our vms doesn't trap ^S/^Q, but leaves it to our server. There are some witches of interest, though, like "set terminal/nottsync", which control vms behavior. Finally, vt100 themselves may trap ^S/^Q, and you may have to set your terminal to not freeze the display on itself. Usually, that's called xon/xoff or flow control, if I am not mistaken. So, the missing vt131/100 termcap entry may be your least problem. ivo welch phd_ivo@gsbacd.uchicago.edu
ngo@tammy.harvard.edu (Tom Ngo) (03/13/89)
In article <3425@silver.bacs.indiana.edu> templon@silver.bacs.indiana.edu (jeffrey templon) writes: > ... I get this horrible mess in the minibuffer: > Failing I-search:^S^S^S^Q- You comment later in your note that you suspect a flow-control problem. You are absolutely correct. Your terminal and host send ^S and ^Q characters to each other to say "Hold on! You're talking too fast!" and "OK, go ahead now." FIX: Include the lines below in your .emacs file. You do not have to change your ^S and ^Q key bindings. It is more compact to set the keyboard-translate table to the correct string without using a loop to construct it, but this method is far easier to read and modify. ;;; Solve flow-control problem by binding ^\ as ^S and ^/ as ^Q (set-input-mode nil t) ; do describe-function for more info ;; Set keyboard-translate-table to do no translations (setq keyboard-translate-table (make-string 128 0)) (let ((i 0)) (while (< i 128) (aset keyboard-translate-table i i) (setq i (1+ i)))) ;; Whenever a ^\ is received, have emacs see a ^S (aset keyboard-translate-table ?\^\\ ?\^s) ;; Whenever a ^^ is received, have emacs see a ^Q (aset keyboard-translate-table ?\^^ ?\^q) ;; Whenever a ^S or ^Q is received, have emacs see nothing (aset keyboard-translate-table ?\^s 0) (aset keyboard-translate-table ?\^q 0) -- --Tom Ngo e-mail: ngo@endor.harvard.edu US mail: 12 Oxford St Box 201 Cambridge, MA 02138 Phone: (617) 495-1768 (office)
jr@bbn.com (John Robinson) (03/13/89)
In article <2240@tank.uchicago.edu>, phd_ivo@gsbacd writes: >>Second problem: [ flow control getting to emacs ] >> >I am neither a GNU, nor a VMS expert. In addition, we are running an old >version of GNU emacs here. However, your symptoms look familiar to me. >^S and ^Q were two unfortunate choices for control character usage, since >it just asks for all sort of problems. ^S and ^Q were unfortunate choices for flow-controlling the terminal/host. Below is my canned file tallking about flow control and how to cope. Also follow its references into files in the emacs distribution. -- GNU emacs (version 18.48 and later) provides several options for coping with terminals or front-ends that insist on using flow control characters. Listed in estimated order of preference. 1. Have Emacs run in CBREAK mode with the kernel handling flow control. Issue (set-input-mode nil t) from .emacs. It is now necessary to find other keys to bind to the commands isearch-forward and quoted-insert. Traditional nominees are C-^ and C-\. There are two ways to get this effect: 1a. Use the keyboard-translate-table to cause C-^ and C-\ to be received by Emacs as though C-S and C-Q were typed. Emacs (except at its very lowest level) never knows that the characters typed were anything but C-S and C-Q, so the use of these keys inside isearch still works - typing C-^ while incremental searching will move the cursor to the next match, etc. Here's some code for this: (setq keyboard-translate-table (make-string 128 0)) (let ((i 0)) (while (< i 128) (aset keyboard-translate-table i i) (setq i (1+ i)))) (aset keyboard-translate-table ?\^\\ ?\^s) (aset keyboard-translate-table ?\^^ ?\^q) 1b. Simply rebind the keys C-^ and C-\ to isearch-forward and quoted-insert. To get continued searches inside isearch it is also necessary to set search-repeat-char to C-^. 2. Don't use CBREAK mode, and cause C-S and C-Q to be bound to a null command. The problem with this is that whatever sent the flow control characters is apt to be falling behind the characters being sent to it, and so what finds its way to the terminal screen will not in general be what is intended. It will be still be necessary to find other keys to bind to isearch-forward and quoted-insert; see 1a and 1b above. Here is a suitable null command: (defun noop () "Do nothing; return nil." (interactive)) 3. Don't use CBREAK mode, and global-unset-key the keys C-S and C-Q. This is similar to #2, except that the flow control characters will probably cause beeps or visible bells. Note that, if the terminal is the source of flow control characters and kernel flow control handling is enabled, it will not in general be necessary to send padding characters as specified in a termcap or terminfo entry. It may be possible to customize a termcap entry to provide better Emacs performance on the assumption that flow control is in use. This effect can also be simulated by announcing (with stty(1) or its equivalent) that the terminal is running at a very slow speed, provided the terminal is not directly wired to the host. Some Background This section attempts to answer the question "Why does emacs choose to use flow-control characters in its command character set?" For another view, please read the comments on flow control in emacs/INSTALL from the distribution; for help with termcaps and DEC terminal concentrators see emacs/etc/TERMS. Flow control was not necessary for most terminals once upon a time, so use of C-S and C-Q for command characters was reasonable. Emacs, for economy of keystrokes and portability, chose to use the control characters in the ASCII character set for its functions, and tried to use mnemonic assignments (S for search, Q for quote). There are other (albeit less common in practice) ways to do flow control that preserve transparency of the character stream. Once emacs' precedent was established, it was too hard to undo. One might even argue that emacs' use of these control characters predates their use by terminals and front-ends for flow control. Notice also that the latter use is ONLY a de-facto standard. In fact, on the model 33 teletype with a paper tape punch (which is VERY old), they were used for the host to turn the punch on and off! So which usage is "right", emacs' or the terminal/front-end manufacturer's? This is a rhetorical (or religious) question; it has no simple answer. -- /jr jr@bbn.com or bbn!jr