Section Four
Register Bit Descriptions
© National Instruments Corporation
4-3
GPIB-1014P User Manual
Where it is necessary to specify a particular bit of a register, the bit position appears as a decimal
number in square brackets after the mnemonic (for example, ISR1[1] indicates the DI bit of
Interrupt Status Register 1).
A minus sign (-) is used to indicate logical negation. An ampersand (&) represents AND, and a
plus sign (+) represents OR in logical expressions.
All numbers, except register offsets, are decimal unless specified otherwise. Register offsets are
given in hexadecimal.
Uppercase mnemonics are used for control, status, data registers, register contents, and interface
functions, as well as GPIB remote messages, commands, and logic states as defined in the IEEE-
488 standard.
After a mnemonic of a name has been defined, the mnemonic is used thereafter. Appendix F
contains a list of all mnemonics used in this manual along with their type and name. Mnemonics
are assigned to messages, states, registers, bits, functions, and integrated circuits. Most mnemonics
contain a clue to their meaning. Table 4-2 contains a list of clues to look for.
Table 4-2. Clues to Understanding Mnemonics
Clue
Mnemonic Probably Stands For:
Ends in IE
Interrupt enable bit
Ends in EN
Enable bit
4 letters,
Interface function as defined in the
ends in S
IEEE-488 standard
Ends in R,
R0, R1, R2
GPIB program register
3 letters,
uppercase
Remote GPIB message
3 letters,
lowercase
Local GPIB message