Cleaned and tested. Working perfect. Perfect sound. See photo 
 
The Intergraph RT915CTW is a vintage, heavy-duty computer keyboard from the 1980s/1990s, often paired with Intergraph graphics workstations. It is known for having built-in audio features, a robust build, and an integrated microphone. 
 
Key Specifications and Features:
 
Model: RT915CTW
Part Number: CTIS08601
Audio Features: Built-in speakers, amplifier, and microphone
Audio Ports: 3.5mm microphone input, headset output
Connector: DIN5
Power Requirement: Requires an external 9V power adapter for the audio features to function.
Functionality: The amplifier and speakers can work without the DIN5 connector if an external 9V power source is provided.
Layout: ISO
This keyboard was designed for specialized, high-end workstations of its era.