On Menu screen will be displayed. At this point you may initiate logon. Such a terminal has many keys designed specifically for it, and your microcomputer may not have corresponding keys, though you may be able to use key combinations for similar effects. A 'keyboard mapping' refers to a list of 3270-type terminal keys and the corresponding keys on your microcomputer keyboard. Keyboard mappings vary depending on which terminal your software is emulating and on the physical capabilities of your keyboard.
Many software packages provide keyboard layout charts for various emulation modes.
In some situations, however, the only way to determine the function of your keyboard keys in CMS is to systematically strike each key and note its effect. Sending Commands to USC Communications Software When emulating a full-screen terminal, your communications software is 'talking' to USC communications software, which in turn talks to the USC system. There are several key combinations that are used to address the USC communications software to perform certain functions. You can tell that the previous command is being processed because the cursor goes to the lower right corner of the screen and remains there. Then when the previous command has been executed, the typed-ahead lines are sent.