ADLINK PCM-9112+ - Manual (Page 46)

38 • Operation Theory
Interrupt Transfer (INTX)
The PCI-9112 provides hardware interrupt capability. Under this mode, an
interrupt signal is generated when the A/D conversion has ended and the
data is ready to be read. It is useful to combine the interrupt transfer with the
timer pacer trigger mode. Under this mode, the data transfer is essentially
asynchronous with the control software.
When the interrupt transfer is used, the hardware interrupt will be inserted
and its corresponding ISR (Interrupt Service Routine) will be invoked and
executed after A/D conversion is completed (the converted data is
transferred by the ISR program). In PCI design, the IRQ level is assigned by
the BIOS directly.
DMA Transfer (DMAX)
The DMA (Direct Memory Access) bus master allows data to be transferred
directly between the PCI-9112 and the PC’s memory at the fastest possible
rate, without using up any CPU time. The A/D data is queued in the local
FIFO on the PCI-9112 itself and it is automatically transferred to PC's
memory.
The DMA transfer mode is very complex to program. It is recommended to
use high-level programming libraries to operate this card. If you wish to
program software’s, which can handle the DMA bus master data transfer,
please refer to the PCI controller manual for more details.