VME User-Level DMA

VME User-Level DMA

A DMA engine is included as part of each VME bus adapter in a Challenge or Onyx system. The DMA engine is unique to the Challenge architecture. It performs efficient, block-mode, DMA transfers between system memory and VME bus slave cards--cards that would normally be capable of only PIO transfers.

The DMA engine greatly increases the rate of data transfer compared to PIO, provided that you transfer at least 32 contiguous bytes at a time. The DMA engine can perform D8, D16, D32, D32 Block, and D64 Block data transfers in the A16, A24, and A32 bus address spaces.

Using the udmalib Functions
Advantages of User DMA
DMA Engine Bandwidth
Example User DMA Function