The D8274 is an Integrated Circuit (IC) component that serves as a Programmable Keyboard/Display Interface. It offers a wide range of features for interfacing keyboards and displays with microprocessors. Let's delve into the key features of the D8274 below:
1. Keyboard Interface: The IC has an 8-row, 8-column keyboard scanning and debounce facility. It supports a matrix keyboard with up to 64 keys. The keyboard can be interfaced using either the pull-down or pull-up mode.
2. Display Interface: The D8274 provides a versatile display interface supporting both static and dynamic displays. It can drive an 8-digit, 16-segment alphanumeric display, or a 16-digit, 16-segment numeric display. The IC also supports multiplexed displays with 8-digit control.
3. Scan and Hold Capability: This IC enables the key scanning process, detecting key closures. It latches the key code of the depressed key until it is read by the microprocessor, ensuring that no data is lost during scanning.
4. Encoder OR/NOR Logic: The integrated encoder logic simplifies the keypad scanning process. The IC includes OR and NOR gates that allow multiple keys to be pressed simultaneously.
5. Interrupt Capability: The D8274 can generate interrupt requests to the microprocessor based on predefined criteria, such as keyboard entry, display requests, or specific status conditions
