# Understanding the Cel Engine and SPORT

"Understanding 3DO Graphics" introduced the cel engine and the SPORT bus. The cel engine projects cels into the frame buffer. The SPORT bus restores the frame buffer background after the cel engine between frames.

This chapter provides more detail about the cel engine and SPORT bus. It also takes a closer look at VH values, which percolate through both the cel engine and the display generator.

This chapter contains the following topics:

- The Cel Engine
- The Data Unpacker (DUP)
- The Pixel Decoder (PDC)
- The Pixel Processor
- The Projector
- SPORT Transfers to the Frame Buffer
- The Path of VH Values