Glossary
G-2
ni.com
ANSI
American National Standards Institute
API
Application Programming Interface—the direct interface that an end user
sees when creating an application.
arbitration
A process in which a potential bus master gains control over a particular
bus.
B
B
Byte—eight related bits of data, an 8-bit binary number. Also used to
denote the amount of memory required to store one byte of data.
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.
BERR*
bus error signal
BIOS
Basic Input/Output System. BIOS functions are the fundamental level
of any PC or compatible computer. BIOS functions embody the basic
operations needed for successful use of the computer’s hardware resources.
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. A VME data
transfer may have no more than 256 elements.
bus
The group of conductors that interconnect individual circuitry in a
computer. Typically, a bus is the expansion vehicle to which I/O or other
devices are connected. Examples of buses include the ISA bus, PCI bus,
VXI bus, and VME bus.
bus error
An error that signals failed access to an address. Bus errors occur with
low-level accesses to memory and usually involve hardware with bus
mapping capabilities. For example, nonexistent memory, a nonexistent
register, or an incorrect device access can cause a bus error.
bus master
A device that is capable of requesting the Data Transfer Bus (DTB) for the
purpose of accessing a slave device.
