Glossary
VXI-MXI User Manual Glossary-4 © National Instruments Corporation
Configuration A set of registers through which the system can identify a module device
Registers requirements. In order to support automatic system and memory
configuration, the VXIbus specification requires that all VXIbus devices h
ave a set of such registers, all accessible from the P1 connector on the
VMEbus.
Configuration The upper 16 KB of A16 space in which the configuration registers for
Space VXI and MXIbus devices exist.
Controller An intelligent device (usually involving a CPU) that is capable of
controlling other devices.
D
DACK DMA Acknowledge
Daisy-Chain A signal line used to propagate a signal level from board to board on a
priority basis, starting with the first slot and ending with the last slot.
Data Strobe A signal used to inform a slave that valid data exists on the bus or used to
request that a slave place data on the bus.
Data Transfer Bus DTB; one of four buses on the VMEbus backplane. The DTB is used by a
bus master to transfer binary data between itself and a slave device.
Daughter Card A board that plugs directly into the expansion connectors of another board.
The VXI-MXI is available with or without a daughter card option called
the INTX card.
Deadlock Unresolved situation in which two devices are vying for the use of a
resource.
DIP Dual Inline Package
DMA Direct Memory Access; a method by which data is transferred between
devices and internal memory without intervention of the central processing
unit.
DRQ DMA Request
DTACK Data Transfer Acknowledge
Dynamic A method of automatically assigning logical addresses to VXIbus devices
Configuration at system startup or other configuration times.