IBM 3174 Reference Guide

Using Your ASCII Terminal
Protected Fields
Nondlsplay Fields
You can override the numeric lock restriction on ASCII terminals since the
keyboards on these terminals operate like typewriter keyboards. To override the
numeric lock restriction, type any character or symbol that corresponds to that
character or symbol appearing in the upper shift on a 3270 Base Typewriter
Keyboard.
Protected fields are areas on the screen in which you cannot type data. For
example, you cannot change field names. A "go elsewhere" message (X < * >) is
displayed on the status line if you attempt to change any data in a protected field.
To recover and enter data, use the Reset key sequence and move the cursor to an
unprotected area of the screen.
In the example, the areas containing Employee Name:, Employee Address:,
Identification Number:, and Salary: are ail protected fields. In addition, the area
in the second half of the screen that contains instructions to the operator is a
protected field.
The application program can define a field as nondisplayable. A nondisplayable
field can be an input field or a protected field. The data in the field is not displayed
on the screen. In the example, the salary field is a nondisplayable field; you
cannot see the information in the field.
Using Your Keyboard
This section contains a brief discussion of keyboard maps and terminal-controlled
keys, and a more detailed description of terminal functions.
Keyboard Maps
On a 3270 terminal, keyboard functions are associated with one key on the
keyboard. For example, you press the PF1 key for the PF1 function. However, the
ASCII terminals that are supported by the 3174 Establishment Controller do not
always have a single key to match all the possible 3270 functions. Therefore, you
sometimes must press two or more keys to carry out one function. For example,
pressing ESC and then pressing 1 causes the PF1 function on many of the
supported terminals.
Every time you press a key (or sometimes, ALT or CTRL plus another key) on your
terminal, a unique ASCII code representing that key is transmitted to the 3174.
These codes identify the function you want to perform. The 3174 may do any of the
following to perform requested functions:
• Initiate the transmission of data to the host
• Echo back a data character for display on your screen
• Send other data back to your terminal, causing the cursor to be repositioned.
The keyboard map defined for your terminal type describes what keyboard function
the 3174 associates with the key sequences you press on the keyboard. The
keyboard maps are found in Appendix A, "Keyboard Maps for ASCII Terminals
Used as 3270 Terminals" on page A-40.
3-8 3174 Establishment Controller Terminal User's Reference for Expanded Functions

IBM 3174 Specifications

General

Brand	IBM
Model	3174
Category	Controller
Language	English