Glossary
© National Instruments Corporation
Glossary-3
VME-MXI-2 User Manual
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backplane
An assembly, typically a printed circuit board, with 96-pin
connectors and signal paths that bus the connector pins. A C-size
VMEbus system will have two sets of bused connectors called
J1 and J2.
backoff condition
A method used to resolve a deadlock situation by acknowledging
one of the bus masters with either a RETRY or BERR, allowing
the data transfer from the other master to complete.
base address
A specified address that is combined with a relative address to
determine the absolute address of a data location. All VME
address windows have an associated base address for their
assigned VME address spaces.
BERR*
Bus Error signal. This signal is asserted by either a slave device
or the BTO unit when an incorrect transfer is made on the Data
Transfer Bus (DTB).
binary
A numbering system with a base of 2.
bit
Binary digit. The smallest possible unit of data: a two-state,
yes/no, 0/1 alternative. The building block of binary coding and
numbering systems. Eight bits make up a byte.
block data rate
Transfer rate when using MXIbus block-mode transfers.
block-mode transfer
An uninterrupted transfer of data elements in which the master
sources only the first address at the beginning of the cycle. The
slave is then responsible for incrementing the address on
subsequent transfers so that the next element is transferred to or
from the proper storage location. In VME, the data transfer may
have no more than 256 elements; MXI does not have this
restriction.
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