Glossary
VXI-1394 Interface for Windows NT/98
G-2
www.ni.com
address modifier
One of six signals in the VMEbus specification used by VMEbus masters
to indicate the address space in which a data transfer is to take place.
address space
A set of 2
n
memory locations differentiated from other such sets in
VXI/VMEbus systems by six addressing lines known as address modifiers.
n is the number of address lines required to uniquely specify a byte location
in a given space. Valid numbers for n are 16, 24, and 32. In VME/VXI,
because there are six address modifiers, there are 64 possible address
spaces.
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.
asynchronous
Not synchronized; not controlled by time signals. In IEEE 1394,
specifically, this is the standard protocol for sending packets that require an
acknowledgment. This guarantees data delivery. The NI-VXI/VISA drivers
for 1394 use this protocol exclusively.
B
b
Bit—one binary digit, either 0 or 1.
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.
