Glossary
G-4
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D
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.
DMA
Direct Memory Access—a method by which data is transferred between
devices and internal memory without intervention of the central processing
unit. DMA is the fastest method of transferring data to/from computer
memory.
DRAM
Dynamic RAM (Random Access Memory)—storage that the computer
must refresh at frequent intervals.
dynamic
configuration
A method of automatically assigning logical addresses to VXIbus devices
at system startup or other configuration times.
dynamically
configured device
A device that has its logical address assigned by the Resource Manager.
A VXI device initially responds at Logical Address 255 when its MODID
line is asserted. The Resource Manager subsequently assigns it a new
logical address, to which the device responds until powered down.
E
ECL
Emitter-Coupled Logic
EEPROM
Electronically Erasable Programmable Read Only Memory—ROM that
can be erased with an electrical signal and reprogrammed.
embedded controller
An intelligent CPU (controller) interface plugged directly into the VXI
backplane, giving it direct access to the VXIbus. It must have all of its
required VXI interface capabilities built in.
EMC
electromagnetic compliance
EMI
electromagnetic interference
external trigger
A voltage pulse from an external source that triggers an event.