Английский язык для пользователей ПК и программистов - Гольцова Е.В.
ISBN 5-7931-0086-5
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How many paragraphs develop (развивают) the problem in this text? Where is the conclusion to the probem? Is it at the end of part one or at the end of the whole article?
Упражнение 17. Где мы находим основную идею любого параграфа? Просмотрите каждый параграф и отметьте его основную идею и текстовые маркеры.
Where can we find the main idea of a paragraph? Look through the paragraphs and mark the main idea of each and text markers.
Упражнение 18. Теперь мы можем закончить написание «содержания» статьи по первому пункту. Вернитесь к упр. 12. ,
Now we can continue writing the contents of the article in relation to the first point of it.
Text
Display Editors
by Peter B. Smith
To begin with, we categorize as display editors those general purpose editors that enable a user to make changes to a document and see the effects of changes immediatly, without having tp issue additional commands. Such editors typically require a display with at least cursor
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addressing capabilities(rather than a teletype). Usually a large portion of the display is dedicated to providing a window into the file buffer.
The commonest conceptual model(due to Irons and Djorup) maps the text onto an infinitely extensible quarter plane. Imagine the file on a two dimensional plane with the first character of the first line at the origin. The user is free to write on the plane to the right and down from the origin. That is, there is no limit on the length of lines or on the number of lines. The editor enables the user to move around the quarter plane and to make changes to the display; using normal cursor control commands, the cursor cannot be moved above the first line of the file or to the left of the first character position on a line.
While to the user it may appear that commands issued modify the file buffer and the display is then modified to represent the new buffer contents. Particular editors may implement extensions to the basic conceptual model. For example, there may be multiple windows into the file buffer and there may be multiple buffer.
Screen
Keyboard
-)
Process 2 (screen updater)
Process 1 (buffer updater)
Record of contents of current screen
File buffer
In this figure Process 1 accepts commands from the keyboard and makes the appropriate changes to the file buffer. Process 2 looks at both the file buffer and a data structure that represents the current screen. It writes characters to the display depending on what the screen currently looks like. A typical alphanumeric screen is 24 by 80 characters so the current screen image would occupy about 2K bytes.
So display editors vary in the relative properties that they give to the two processes of the figure above. It is a little annoying, for example, if the editor persists in redrawing part of the screen that is already out ofxiate. Fig. below shows a two overall strategies. In (a) the screen is completely updated after one command before the next command is processed. In (b) repainting may be interrupted to process a command.
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command interpretation and screen updating strategies
(a) repeat if command to be interpreted
then Update file buffer
if screen out of date then Update screen until exit
(b) repeat while there is a command to be interpreted
update file buffer while (screen is out of date) and no command to be interpreted
update screen a little (more) until exit
Next, terminals vary in the control characters that they use to direct cursor movement, perform scrolling, clear sections of the screen and so on. There will typically be some mechanism,such as virtual screens or an editor accessible file of terminals.
E
The e editor developed by the Rand Computation Center uses control characters for control functions, such as cursor movement and initiating string searches. Non-con-trol characters are either inserted at the current cursor position or overwrite the character at that position. Insert/Over- write mode is toggled with a simple command, an indicator on the screen indicates the current mode. The user can have multiple windows (possibly into different files); a "change window" command moves to the next window in a circular list. A keystroke history file is generated as the user types and, in the event of an uncontrolled exit, the history can be replayed. A variety of commands can be issued in "command mode" "including some oriented towards document preparation such as filling and justification of paragraphs.
The editor does unexpected things to tabs and spaces on lines that it modifies. Trailing tabs and spaces are deleted, groups of leading spaces are converted to tabs and embedded tabs are converted to spaces.
EMACS
EMACS is probably the most widely available fullscreen editor. Implementations of it, and clones are available on a large variety of sys from super computers to micros. There is even a USENET news- group (comp.emacs)
