Using Glass TTY Terminals › TTY Environment

TTY Environment

Cursor Position

Cursor position on mapout is specified in the map-definition. A mapout operation writes a map to the TTY and positions the cursor as it would be positioned on a 3270-type terminal.

Attribute Byte

Each field on mapout is physically preceded by an invisible attribute byte. A display symbol for the attribute byte can be defined in a device independence table. Attribute byte symbols can be used to mark the location of the field and to inform the operator whether the field is unprotected, delimited, blank and protected, or in error. Default attribute byte symbols are presented in the following table:

The attribute byte symbols that are defined in a device independence table provide the terminal operator with information about a given field. The symbols that are presented in this table can be overridden when a device independence table is generated.

Protected Fields

TTY terminals do not physically protect fields; the operator can key characters into any location on the map. Data keyed into a field that is defined as an UNPROTECTED field is transmitted and processed as usual. Data is ignored on mapin if it is typed into a field that is designated as PROTECTED or into a portion of the map on which no fields are defined.

Keys

Each terminal defines the keys or key sequences that cause the cursor to be moved on the screen. Terminal-defined key associations must be repeated in a device independence table that is generated for a given terminal. The key assignments presented in the following table are typical for some glass TTY terminals. Documentation for any given terminal should be consulted for the cursor-movement key assignments that are valid for that terminal.

Typical Cursor Movement Keys

A device independence table specifies the terminal-defined keys or key sequences that are used to move the cursor on the screen. The TTY key associations presented in this table are typical of some glass TTY terminals. Documentation for any given terminal should be consulted for the cursor-movement key assignments that are valid for that terminal.

TTY control keys can be defined to act like 3270-type attention keys. Attention key assignments that are typical for some glass TTY terminals are listed in the following table. Documentation for any given terminal should be consulted for the attention key assignments that are valid for that terminal.

The operator presses a TTY key or key sequence to invoke the 3270-type function associated with the key in the device independence table. The right-hand column of this table presents the RHDCTTBL statements that establish these particular key relationships.