User manual

Glossary

B bytes

backplane An assembly, typically a printed circuit board, with 96-pin

connectors and signal paths that bus the connector pins. A C-size

VXIbus system will have two sets of bused connectors called J1

and J2. A D-size VXIbus system will have three sets of bused

connectors called J1, J2, and J3.

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 VXI

address windows have an associated base address for their

assigned VXI 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). The BERR* signal is also used in VXI for

certain protocol implementations such as writes to a full Signal

Serial Protocol.

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.