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13.8 Display Options

Character Cell Size {Char Cell}

This is the size of the cell in which a character fits. It is measured in pixels (=tiny dots). The more dots, the better the resolution. 10x16 is 10 dots wide by 16 dots high (16 rows and 10 columns). Note the notation is inverted as compared to the notation for matrix dimensions which gives rows (height) first.. Also, the character cell includes rows and columns of pixels allocated for the space between adjacent characters so the cell size which defines the boundaries of an actual character may be smaller.

Columns/Lines

Usually 80 columns and 24 or 25 lines. This means that there may be up to 80 characters in a row (line) on the screen. Many terminals have a 132 column option but unless you have a large screen, the tiny characters may be hard to read. {{Set 132 column mode}}. If you set 25 lines, make sure that this is in the terminfo. You should also put "export LINES=25" into /etc/profile and also use: "stty -F /dev/ttySx rows 25". If you don't it might result in a scrolling problem (see Terminal doesn't scroll

Cursor

The cursor may be set to appear as a rectangle (= block) {Blk}. Other options are underline {Line} or blinking. I prefer non-blinking {Steady} block since it's big enough to find quickly but there is no distractive blinking. If you set it invisible (an option on some terminals) it will disappear but new letters will appear on the screen as you type at the invisible cursor.

Display Attributes (Magic Cookies)

Display Attributes may either be magic cookies or be attribute bytes assigned to each character. For magic cookies, there is a limit to their extent: Are they in effect to the end of the line or to the end of the page? It's best to use attribute bytes (which could actually be half-bytes = nibbles).

Display Control Characters {Monitor}

May be called various names such as "Display Controls". When off (normal) it's "Interpret Controls". When set on, you see the escape sequences from the host (which you normally never see on the screen). So that these sequences may be viewed in sequence on a line, they are not acted upon (interpreted) by the terminal. Except that a CR LF sequence creates a new line. See Control Codes.

Double Width/Height

Some terminals can have their characters double width and/or double height. This feature is seldom needed. When changing a line to double width (DW) the right half (RH) is pushed off the screen and there is the question of whether or not to delete (erase) it. "Preserve" means to keep the RH of DW lines. When in double height mode, it may be necessary to send each such line twice (the 2nd time down one row) in order to get a double-height line on the screen.

Reverse Video {Display} (Background Light/Dark)

Normal video is light (white, green, amber) letters (foreground) on a dark (black) background. Reverse video {Display Light} is the opposite: black text on a light background. This is easier on the eyes (unless the room is dark).

Status Line

A status line is a line at the top or bottom of the screen that displays info about the application program you are running. It's often highlighted in some way. With a status line enabled, an application can send the terminal a special escape sequence which means that the text that follows is for the status line. However, many applications don't use this feature but instead only simulate a real status line by direct cursor positioning. The ordinary user looking at it doesn't know the difference.

Upon 80/132 Change: Clear or Preserve?

When switching the number of columns from 80 to 132 (or conversely) should the data displayed in the old format be erased (cleared) or preserved? {80/132 Clr} {{Screen Width Change}}. It should make no difference how you set this option since if an application program uses 132 columns, it should set this option appropriately via a control sequence.

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* Text Terminal How-To Index

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