ugBASIC User Manual

   DOUBLE BUFFER [ON|OFF]

The DOUBLE BUFFER is a command that enable / disable the graphics programming technique used to avoid screen flickering, which is especially noticeable in animations and interactive graphics applications. It is especially useful in 8-bit computers, where graphics resources are limited.

Imagine having a screen and two areas of memory, called buffers, dedicated to graphics. In the first the entire frame (the complete image) that we want to display on the screen is drawn. While drawing in the first buffer, the contents of the second buffer are displayed on the screen. Once the drawing in the first buffer is complete, the two buffers are swapped: the contents of the first buffer are copied to the second and displayed on the screen, while the first buffer is emptied and prepared for the next frame. This process is repeated continuously.

The command will enable this method, and screens will be swapped if the SCREEN SWAP is used.

This instruction activates the technique only where available.

  DOUBLE BUFFER ON

 DbBf

• Commodore 128 (MOS 8502)
• Commodore 64
• Commodore 64+REU
• Olivetti Prodest PC128
• TRS-80 Color Computer 3

SCREEN SWAP

If you have encountered a problem using this command, if you think there is a bug or the explanation is unclear, please open an issue for this keyword on GitHub. Thank you!