Output Translation - IIIIIIAPL*PLUS System FOR

outputtrt=

The session parameter outputtrt= specifies an optional output translation table that is used instead of the translate table built-in to the system. This table controls the character sequence transmitted to the terminal for each of the 256 possible APL character values. All normal APL output to the terminal is affected. including input that is displayed while you type.

The outputtrt= parameter is primarily used to make APL work with specialized terminals that do not conform to the APL/ ASCII typewriter-paired standard. Thus. the file VT220TAB contains translations specific to STSC's downloaded character set for the VT220 terminal. The following tables are available:

aplotab a translate table for APL/ASCII typewriter-paired terminals

bitotab a translate table to be used with bit-paired terminals. such as the HP 2641 A.

rawotab a translate table that causes each element of OAV to be output with no translation at all

vt220tab a translate table for VT220 terminal with downloaded APL characters.

An output translation file should be a regular VMS sequential Stream_LF file containing exactly 256 lines. The lines should be

delimited by the line feed character (OTC LF in APL, not OTC NL), as would be produced by the VMS editor. For example, the 48th character of OAV (origin 1) is slash (/), so line 48 of the file should contain the character / .

A new translate table can be used to change the display form of characters in APL's OA V or to define display forms for characters that are not presently defined. It does not allow you to define new overstrikes that are accepted for input, although it can be used to control how valid overstrikes are displayed. For example, it can be used to control whether characters from OA V [97] to OAV [ 122]

are displayed as ABC . ..

Z

or a be ... z.

For convenience, the same notation as is used in term cap flIes can be used to denote characters that are difficult to produce explicitly using a text editor:

\E means the escape character (decimal 27)

"G means the BEL character (decimal 7)

\010 means octal 10 (decimal 8), also known as backspace or Ctrl-H

\ \ means a single backslash.

Each sequence of characters should actually cause only a single character to be displayed on the terminal. If the sequence causes the cursor to move anywhere other than one position to the right, the terminal display will become unsynchronized with the session manager.

Input Prompt String prompt=

The session parameter prompt= is used to specify a string that serves as the APL input prompt. Any string can be used, but the most useful value is the ASCII BEL character, which causes the terminal to beep when input is expected (much like an APL time sharing system).

If a personal computer is being used as a terminal, the BEL prompt can provide a useful termination character for a DARB IN-based data transfer protocol on the PC; for example:

$ apl prompt="'G

where "'G is a notation recognized by APL for Ctrl-G.

"Customizing Logical Keystrokes" later in this section contains a description of this notation.)

Scrolling Memory Pages screens=

The session parameter screens= specifies the number of screens of scrolling memory reserved for the image of the APL session. For example:

$ apl screens=lO

specifies ten screens. This memory is allocated from the block of storage reserved for the editor, and it may be necessary to increase the editor memory (with the editmem= session parameter) in order to have enough space.

Terminal Initialization status=

Several session parameters are used to initialize the terminal or specify terminal behavior. The status=n is used to set the initial state of insert mode, status line, and keyboard:

status=O insert off, status line off, APL keyboard status=l insert mode on

status=2 status line on in APL Session Manager (Default) status=4 text keyboard instead of APL keyboard.

Combinations are specified by the sum of the values for the intended state. For example:

$ apl status=5

specifies insert mode on, status line off, and text keyboard.

Initialization Strings

terminit= and termdinit=

The session parameter terminit= specifies a character sequence that is transmitted to the terminal upon entry into APL. The default sequence is the ASCII character SO (Ctrl-N) to switch the terminal into

the APL character set. The session parameter termdinit= specifies a corresponding string that is transmitted upon exit from APL; its default is the ASCII character SI (Ctrl-G). The termdinit= and termini t= strings are also transmitted when 0 eM D and ) eM Dare used to execute a VMS DCL command from APL.

Both strings can be set to empty, effectively nullifying the default. For example:

$ apl terminit= termdinit=

Specifying empty strings is recommended on terminals where the default strings produce unwanted effects.

Identifying the Terminal to APL terminal=

The terminal= parameter identifies the terminal name to APL. The terminal name will then be used in conjunction with the term cap database to provide a common set of terminal facilities for a wide variety of terminal types. The terminals supported in the supplied terminal database are:

To specify a terminal, use the appropriate abbreviation, as in:

Custom Termcap termcap=

$ apl terminal=vt200

The APL

*

PLUS System for V AXNMS uses exactly the same structure for entries in the termcap database as are used in the UNIX

environment. The facility is general enough to enable APL to provide

effective full-screen control on virtually any CRT display terminal. It

is possible to develop your own termcap entries for terminals not presently included in the

atermcap

file supplied by STSC.

you do, you can specify your own file instead of STSC's

atermcap file

by using the

termcap=

parameter, as in:

$ apl termcap=filename

Since most terminals used in the VMS environment are designed to

Im Dokument IIIIIIAPL*PLUS System FOR (Seite 39-43)