SAS Companion for the OS/390 Environment

Terminal Support in the OS/390 Environment

The information in the following sections may be useful to you if you use graphics or special device drivers in the SAS windowing environment.

Text Device Drivers

SAS uses two interactive windowing text (nongraphics) device drivers: a non-Extended-Data-Stream (non-EDS) driver and an Extended-Data-Stream (EDS) driver. An EDS device supports IBM 3270 extended attributes such as colors and highlighting, whereas a non-EDS device does not. Note that EDS devices also support the non-EDS data stream. The ability to do graphics on a 3270 terminal implies that it is an EDS device. Examples of EDS and non-EDS IBM terminals are

EDS Non-EDS

3179, 3290 (LT-1) 3277

3279, 3270-PC 3278 (most)

3278 with graphics RPQ 3290 (LT-2, 3, or 4)

EDS	Non-EDS
3179, 3290 (LT-1)	3277
3279, 3270-PC	3278 (most)
3278 with graphics RPQ	3290 (LT-2, 3, or 4)

On non-EDS terminals, vertical window borders occupy three display positions on the screen: the first position for the field attribute byte, the second position for the border character itself, and the third position for the attribute byte for the following field. Because a window has both left and right vertical borders, six display positions are used by the vertical borders. Therefore, on an 80-column non-EDS device, the maximum display/editing area in a window is 74 columns.

Vertical window borders on EDS devices occupy two display positions: the border character and the attribute for the next field (left vertical border) or the attribute and the border character (right vertical border). Therefore, on an 80-column EDS device, the maximum display or editing area in a window is 76 columns.

Graphics Device Drivers

There are two 3270 graphics device drivers in the SAS windowing environment: the Programmed Symbol driver and the Vector-to-Raster driver. On terminals that support graphics, these two drivers are used to produce graphics as well as mixed text and graphics. Both graphics drivers communicate with the text driver, which controls the terminal display.

The Programmed Symbol graphics driver uses user-definable characters to display graphics. A programmed symbol is a character on the device in which certain pixels are illuminated to produce a desired shape in a position (cell) on the display. A loadable programmed symbol set is a terminal character set that contains these application-defined programmed symbols. (The default symbol set on a device is the standard character set--that is, those symbols that are normally displayed and that can be entered from the keyboard.) Examples of terminals that use programmed symbols to display graphics are the 3279G, 3290, and 3270-PC.
The Vector-to-Raster graphics driver is used to produce graphics on terminals that support graphics drawing instructions such as MOVE and DRAW. Examples of these devices are the 3179G/3192G and the IBM5550. The 3179G/3192G terminals also have limited support for programmed symbol graphics.

EMULUS Extensions

When used with Emulus 3270 terminal emulation software, the SAS 3270 device drivers provide workstation-like capabilities that can greatly enhance SAS/GRAPH software, as well as applications that are developed using SAS/AF software. These capabilities include the following:

use of local workstation memory for graphics

offers significant performance improvements for SAS/AF applications because a local copy of graphics is stored in the workstation memory rather than being continually retransmitted from the mainframe.

color loading by RGB value

enables applications to use more colors than just the standard 8 or 16 graphics colors that they would use on a typical 3270 terminal or terminal emulator.

rubber-banding

enables you to create, resize, and move objects. For example, you can:

create or size graphics objects by dragging the workstation mouse in the SAS/GRAPH Graphics Editor
easily drag and position objects in the SAS/AF Frame Editor
rotate a plot when using SAS/INSIGHT software
resize or move SAS windows.

dynamic graphics cursor shapes

enables applications to change the shape of the graphics cursor to indicate the state of the application. For example, the graphics cursor typically changes shape when a user drags an object or rotates a plot.

Using a Mouse in the SAS Windowing Environment under OS/390

The IBM 3179G, 3192G, 3472G, and 5550 terminals are all graphics terminals that support the use of a mouse. The IBM 3179G, 3192G, and 5550 terminals use the three-button IBM 5277 Model 1 optical mouse, whereas the IBM 3472G terminal uses the two-button PS/2 mouse.

SAS recognizes when the mouse is attached and automatically places the graphics cursor under the control of the mouse.

Using a Three-Button Mouse

The IBM 5277 Model 1 optical mouse has three buttons:

leftmost button: SAS uses the leftmost button as an ENTER key. The ENTER key is used to select menu items; to grow, shrink, or move windows; to scroll using scroll bars, and so on. Therefore, having the ENTER key on the mouse is useful. The text cursor moves to the location of the mouse cursor whenever you press this mouse button.
center button: By default, SAS assigns a function key to the center button. You can use the KEYS window or the KEYDEF command to change the definition of this button. The button is designated as MB2. See the help for base SAS for more information about the KEYS window and the KEYDEF command.
rightmost button: The rightmost button is a reset button that unlocks the keyboard.

For additional information about using a mouse, refer to the appropriate documentation at your site.

Using a Two-Button Mouse

The 3472G terminal is a multiple-session graphics terminal. This device uses the two-button PS/2 mouse. With the graphics cursor attached, these buttons have the same functions as the leftmost and center buttons on the three-button mouse.

Appearance of Window Borders, Scroll Bars, and Widgets

Depending on the type of terminal, SAS uses either programmed symbols or APL symbols to create window borders, scroll bars, and widgets (radio buttons, push buttons, and check boxes). This can cause SAS windows to look somewhat nicer on some terminals than on others.

On devices that support programmed symbols, the SAS windowing environment uses a predefined set of programmed symbols for its window components. Programmed symbols give window components a nicer appearance than APL symbols. These programmed symbols are available for the four most common character cell sizes: 9 x 12, 9 x 14, 9 x 16, and 6 x 12. Programmed symbols are not used for any device that has a different character cell size (for example, 10 x 14 on a Tektronix 4205), even though the device supports programmed symbols.
On 3270 terminals that do not support programmed symbols, but that support the APL(footnote 1) character set, the SAS windowing environment uses APL symbols. APL is supported only on EDS devices, including all nongraphic 3279 and 3179 terminals, and on many PC 3270 emulators.

Improving Screen Resolution on an IBM 3290 Terminal

The IBM 3290 terminal gives you the ability to change character cell size (and therefore, to change screen resolution). This capability is useful if you are working with graphics, for example.

You use the CHARTYPE= system option to modify the character cell size. For example, on a 3290 terminal that is configured as having 43 rows by 80 columns, CHARTYPE=1 (the default) produces a 62 x 80 display size.

If you specify CHARTYPE=2, the display size will be 46 x 53. Note that if you configure the 3290 as 62 x 160 (the maximum display size available on the 3290), CHARTYPE=2 results in a display size of 46 x 106. This results in a very legible and attractive windowing environment. See CHARTYPE= for more information about this option.

Note: If you are running in interactive graphics mode and you receive a message, your display may become corrupted. To correct this and return the screen to its original display, press ENTER in response to the SCREEN ERASURE message. Alternatively, you can configure the 3290 as one logical terminal with a 62 x 160 character cell size. [cautionend]

FOOTNOTE 1: The APL language relies heavily on mathematical-type notation, using single-character operators in a special character set.

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