KBD - Keyboard

Enhanced Definition

In the mainframe context, a Keyboard (KBD) refers to the primary input device associated with an IBM 3270 terminal or its software emulator. It is specifically designed for interacting with z/OS applications and systems, facilitating the entry of commands, data, and navigation within `green screen` interfaces. Unlike PC keyboards, mainframe keyboards operate predominantly in a `block mode` fashion.

Key Characteristics

- 3270 Terminal Integration: Exclusively designed for use with IBM 3270 display stations (physical or emulated), which are character-cell, fixed-format terminals.
- Dedicated Function Keys: Features specialized keys like PF (Program Function) keys (PF1-PF24), PA (Program Attention) keys, Enter, Clear, New Line, and Field Exit, which trigger specific actions on the host.
- Block Mode Operation: Input is buffered locally by the terminal and sent to the host in a single block only when a specific key (e.g., Enter, PF key, PA key) is pressed, rather than character-by-character.
- Field-Oriented Input: Data entry often occurs within predefined, protected, or unprotected fields on the screen, managed by the 3270 data stream and application logic.
- Keyboard Lock: The keyboard can be locked by the host application (e.g., during processing or when waiting for a response), preventing further input until unlocked.

Use Cases

- TSO/ISPF Interaction: Navigating ISPF panels, entering TSO commands, editing JCL or program source code in ISPF editor sessions.
- CICS/IMS Transaction Processing: Inputting data into transaction screens, selecting options, and navigating through application flows in CICS or IMS environments.
- System Console Operations: For system programmers and operators, using a console keyboard to issue system commands, respond to messages, and manage z/OS system resources.
- Data Entry Applications: Performing high-volume data entry into legacy green screen applications, such as order processing, inventory management, or financial systems.
- Debugging and Testing: Entering commands into debuggers (e.g., Xpediter, Debug Tool) or test harnesses to step through code and inspect variables.

Related Concepts

The Keyboard is intrinsically linked to the 3270 Terminal architecture, serving as the user's primary interface to TSO/ISPF, CICS, IMS, and other z/OS applications. Its block mode operation is fundamental to the efficiency of VTAM and SNA networks, as it reduces network traffic compared to character-at-a-time input. The functionality of PF keys is often programmed by applications (e.g., ISPF panels, CICS maps) to provide quick access to common functions, making the keyboard a critical component of user experience and productivity within the z/OS ecosystem.

Best Practices:

Master PF Key Usage: Learn and utilize the PF (Program Function) keys extensively, as they are often mapped to common actions (e.g., PF3 for Exit, PF7/PF8 for scrolling) and significantly improve efficiency in ISPF and other applications.
Understand Block Mode Behavior: Be aware that input is not processed until an Enter or PF key is pressed; avoid rapid typing followed by Enter if the screen is still updating.
Leverage Terminal Emulator Features: When using a 3270 emulator, utilize features like macros, copy/paste, and session management to enhance productivity and automate repetitive tasks.
Secure Unattended Terminals: Always log off or lock your terminal session when stepping away, especially in sensitive environments, to prevent unauthorized access.
Familiarize with Application-Specific Key Mappings: Different applications may assign unique functions to PF keys or require specific key combinations; consult application documentation for optimal use.