Almathera Ten Pack 3: CDPD 3/Almathera Ten on Ten - Disc 3: CDPD3.iso/scope/126-150/scopedisk143/vlt4.824/docs/vlt4p226.doc

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                VLT 4.226  Additional Documentation
                ===================================

                        (C) Copyright 1989

                               by

                        W.G.J. Langeveld

                Stanford Linear Accelerator Center


General
=======

    The most prominent features of this release are a scrollback buffer
with all sorts of bells and whistles (such as ARexx control!), and full
support of External Protocols following version 2.0 of the specification.
    This release is the first to come in two different flavors. By
popular request, there is now a version of VLT called VLT jr. which does not
have the Tektronix emulator. This saves some 35k in the size of the
executable, which is substantial if you never use graphics and are cramped
for disk space. For that reason there are now two archives, that are
identical except for the executable. When you read this, you have hopefully
downloaded the one you wanted. For the occasion, VLT has also acquired a new
icon, which is considerably smaller than the previous one.
    Before describing the new features, let me first address some minor
things that changed.

The minor changes
=================

    The Tektronix emulation pretty much is the same, except that the
Graphic cursor (cross hair) is now allowed to address the top part of the
4096x4096 address space. It used to be limited to 3120 in the vertical
direction. Also, when the Tektronix screen is reopened because of receipt of
the clear Tek screen command sequence from the host, the screen is no longer
redrawn before being erased, which was a little silly.
    VLT now supports ANSI background colors. In order to use these, select
Rendering Mode = Color, and make sure that the ANSI Color subitem is checked.
When VLT receives ANSI color sequences it will in that case also respond to
requests to change the background color: <esc>[40m through <esc>[47m.
    VLT's menus have changed a little. The Kermit Options submenu now has
an item that allows one to set the maximum packet size. The Change Directory
subitem that used to be there was moved to the main Transfer menu, because it
affects the default directory of all protocols (in fact of VLT in general) and
not only that of Kermit. The default directory is now also saved with the
configuration. On startup, VLT CD's automatically to that directory. If you do
not want this to happen, save your configuration with an empty string for the
current directory. The next time VLT will come up in the directory you executed
it from.
    The displays for file transfers now contain a lot more information,
even though the built-in protocols don't update many of the fields yet.
However,  Rick Huebner's XPRzmodem updates almost all fields.
    The maximum allowed serial buffer size is now enforced and set at 32k.
Entering a larger size would sometimes lead to a crash.
    A small problem with updating the menu check marks afer certain script
commands was fixed.
    The font selection code was again rewritten. The VLT graph font would
remain 11 points tall after switching to 8 point fonts, and probably v.v.
OpenFont is too darn smart, if you ask me (or stupid, as the case may be).
    A long-standing but not usually very noticable bug with VLT's
handling of <can> (^X) characters was finally found. Under certain
circumstances, this character was interpreted as introducing an escape
sequence, rather than cancelling one.
    Aborting a VLT script (not an ARexx macro) can now be accomplished
from the keyboard by typing the escape key.
    The position of the screen function gadgets was optimized a little for
the various modes of operation.
    With VLT running on its custom screen, the console window is now
sizable and draggable, just as with VLT running on the Workbench. However,
there are no front/back gadgets. People that use window/screen rearrangement
tools should beware of the possibility that the console window (and any other
windows VLT uses) may wind up behind the main borderless window. It is usually
possible to push this borderless window behind all other windows, and this
should make such things as the console window reappear.
    By request, the VT100 answer-back string (Device Status Report, DSR) is
now programmable by means of a script command called setdsr. The DSR is VLT's
response to the sequence <esc>[c from the host. VLT used to respond, and the
default is currently: <esc>[1;7c. Only the part *after* the <esc> should be
given in the setdsr command: e.g. setdsr [1;2;7c. The DSR string is stored as
part of the configuration file.
        The right-Amiga V keyboard command no longer displays VLT's version
number. It is now associated with the review buffer.


XPR support
===========

    One of the major changes is the full support of the XPR spec as of XPR
version 2.0. This involved a few changes to VLT's serial handling code, but
extensive testing has shown that nothing is seriously broken.
    All functions mentioned in the XPR 2.0 document are now supported.
However, they have only been tested using a beta version of Rick Huebner's
XPRzmodem 2.0 and an alpha version of Steve Walton's Kermit, as turned into an
XPR by Marco Papa. As mentioned earlier, the status display has been
considerably enhanced, which together with the xpr_options function is the main
culprit for the increase in size of VLT.
    Initialization strings will now be taken from environment variables if
they are set up. For example, if you type

    1> set xprascii=50

    from a CLI, then this value (50 ticks) will be the default delay
between 80 character blocks using the xprascii.library. Similarly for the
initialization strings of other XPRs, see their documentation.
    It turns out that the script commands XPR SEND and XPR RECEIVE have
never worked properly. They do now.


Review Buffer
=============

    The other major enhancement is the addition of the review (scrollback)
buffer. It comes in the form of a library ("review.library"), so that people
that don't have enough real estate (memory and disk-space wise) don't have to
use it. If you can't afford the space or memory, just delete the review.library
from the libs: directory, and VLT will not use it. Review.library takes up
about 20k worth of disk space. However, its buffer size is adjustable, so you
can  choose how much memory it takes up if you do use it.
    The history buffer stores the text that the host sends to VLT in a
circular buffer of a particular size that can be changed by the user. If the
buffer becomes full, the oldest parts of the text "scroll off the top", i.e.
are lost. Line oriented hosts (such as your average VAX and BBS) send lines of
text followed by a "return" character. With such hosts, the review buffer just
appends the new lines of text to the bottom of the buffer as they come in, and
if necessary discards lines from the top of the buffer. However, there are also
page oriented hosts, such as IBM mainframes running VM/CMS, and other systems
when running page oriented applications. With such hosts, the review buffer
will keep a record of what is on each page, scrolling a page at a time if the
page is cleared by the host or from the menu. Individual changes on any one
page in particular are not kept track of, however. Also, the review buffer
does not remember the color of any text or if the text used graphics fonts.
    Note, that the history buffer is not a substitute for the capture
facility. The main purpose of the history buffer is to keep track of what was
displayed on VLT's screen at all times. To ASCII download files you still
should use the capture facility or the XPRascii protocol.
    The history buffer is also used to restore VLT's screen contents when
you change the number of lines or columns, or when you change the properties of
the screen e.g. to have more or fewer colors, be in a different interlace mode,
to be on the Workbench or when the window is resized when you are on the
Workbench. Since the review buffer doesn't remember which color was used, the
restored screen will always be "monochrome", and may look funny in places if
the original contents used any of the graphics fonts.
    When you save your configuration, the current size of the review buffer
is also saved, as well as the dimensions and location of the review window when
it was last opened.
    The following sections explain how to manipulate the history buffer in
detail.

History Buffer: View
--------------------

    There is a new menu item in the VLT menu, called History Buffer, with
two subitems. The first one, "View", opens the Review window and allows you to
scroll through the history of what used to be on VLT's screen, using scroll
bars at the right-hand side and at the bottom. This option now has the keyboard
command right-Amiga V, which used show VLT's version number.
    The review window has its own menus, described below.

Buffer menu:
- - - - - - -

Clear       - Clears the buffer, wipes out all contents.
Save        - Saves all selected (see later) lines to the current file.
              (This overwrites what was previously in that file).
Save As     - Saves all selected lines to a file. Brings up a file requester.
New Page    - Resets the history buffer to start a new page. For use with page
              oriented hosts. Prevents the host from overwriting the current
              "page".
Buffer Size - Allows the user to change the buffer size. For speed reasons, the
              history buffer is a little wasteful with memory. The number of
              lines of history equals the size divided by the number of columns.
              Note, that when the number of columns is changed, the review
              buffer is automatically adjusted to the new number of columns,
              with the same buffer size. Therefore, when the new number of
              columns is larger than the old number, the top lines of the
              review buffer will be lost. VLT enforces a minimum number
              of columns of 80, so that resizing the window on the Workbench
              to less than 80 columns doesn't cause too much data to be lost.
Quit        - Closes the review window.


Select menu:
- - - - - - -

Select All       - Select all lines in the buffer. Only selected lines can be
                   saved. Before trying to save anything you must first select
                   your lines.
Deselect All     - Causes all lines in the buffer to become unselected.
Invert Selection - Causes all selected lines to become unselected and all
                   unselected ones to become selected.


Move menu:
- - - - - -

    The options in this menu allow you to browse around in the history
buffer. You can do this a line at a time or a "page" at a time. A page in this
context means the number of lines displayed in the window. These functions are
also available from the keyboard with arrow keys and the shift and ctrl keys.
Remember that in order for this to work, the review window has to be the active
window. Of course, you can also use the scroll bars.


Search menu:
- - - - - - -

Search Forward - Search from the top of the buffer down to a certain string.
                 This option will request a search string from the user.
Search Reverse - Search from the bottom of the buffer backwards to a certain
                 string. This option will also request a search string.
Repeat Forward - Search forward for another occurrence of the search string.
Repeat Reverse - Same, but in the backward direction.


History Buffer: Edit/Send
-------------------------

    There is another subitem in VLT's History Buffer submenu: Edit/Send.
This item causes selected lines to pop up in a string requester. You can then
change these lines interactively. If you press the return key, the modified
string is sent to the host. If you click on Cancel, the next selected line is
presented, etc. If you enter an escape character as the first character in the
line, or if you press the escape key in VLT's main window, or if you select
Edit/Send from VLT's menu again, this process stops. In any case, all lines
that are presented to the user this way are automatically deselected.
    This subitem can be invoked from the keyboard by holding the
right-Amiga key and pressing the TAB key (don't get confused with
right-Amiga I!).


Mouse Support
-------------

    Aside from using the menu options in the Review Window's Select menu,
you can also use the mouse to select and drag-select lines. To select a line,
just click on it with the left mouse button. To deselect it, click on it again.
You can also drag select. First click on a line you want to select or deselect.
Hold down the left mouse button, and drag the mouse up or down. When the first
line was a selected line, it becomes deselected, and all other lines you move
the mouse across also become deselected: the line you click on first,
determines whether you will select or deselect in the drag-select operation.
When you move the mouse over the top or bottom line, the display will start to
scroll (a line at a time). If you drag the mouse a little higher or lower, the
scrolling speed will become higher (a quarter page at a time). To select most
of the buffer except for a few lines, use drag-select in combination with the
menu options for selecting lines.


Script/ARexx support
--------------------

    There is a new script command to manipulate the review history buffer.
The command is "review", and it has many suboptions that are described in the
table. below. All commands consist of a single character, and some of them allow
an "argument". There may be white space between the command and the argument
but there doesn't have to be.


Command: | Argument:      | Meaning:
---------+----------------+--------------------------------------------------
         |                |
    A    | <filename>     | Save selected lines to <filename>.
    B    | <size>         | Set buffer size to <size> bytes.
    C    |                | Clear review buffer.
  S,D,I  |                | Select, Deselect, Invert all lines.
  S,D,I  | S              |    "       "        "    Search line only.
  S,D,I  | T              |    "       "        "    from search line to top.
  S.D.I  | B              |    "       "        "    from search line to bottom.
    J    | <lines>        | Jump relative to search line by <lines> lines.
         |                |   Negative numbers search towards top.
    K    | <line>         | Jump relative to <line> from top.
         |                |   0 is top line. Negative numbers count from bottom:
         |                |   -1 is bottom line.
    F    | <string>       | Search from top Forward for <string>.
    R    | <string>       | Search from bottom in Reverse for <string>.
    G    |                | Repeat search Forward.
    T    |                | Repeat search Reverse.
    H    | <string>       | Search from last search position Forward for <string>.
    Y    | <string>       | Search from last search position Reverse for <string>.
    M    | UL  UP  T      | Move Up    Line, Up    Page, to       Top.
         | DL  DP  B      |  "   Down  Line, Down  Page, to       Bottom.
         | LC  LP  LM     |  "   Left  Char, Left  Page, to Left  Margin.
         | RC  RP  RM     |  "   Right Char, Right Page, to Right Margin.
    O    |                | Open window.
    P    |                | Scroll page (saves what is currently on screen).
    Q    |                | Close window.
    U    |                | Update window.
    X    | <name>         | If previous command successful, set environment
         |                |   variable <name> to current search line. Else
         |                |   erase the environment variable <name>.
    W    |                | Resave to current file (overwrites existing file).
         |                |



    To play around with these commands, switch on VLT's console window
and type such things as:

        ~rev "S"
    ~rev "R some_string"
    ~rev "M UP"

    Etc. Well, that's it for this version, have fun!




    Willy Langeveld, 9 October 1989