BASICA/QuickBASIC GPIB-PC Function Calls Section Four AGPIB-PC User Manual 4A-6 ©National Instruments Corp.perform arithmetic operations on the data and want to avoid theoverhead of converting the character bytes of IBRD and IBWRT intointeger format and back again.IBRDI and IBWRTI are passed data in the form of an integer array,instead of a character string whose maximum length is limited to 255bytes. Using these functions, you may store more than 255 bytes in asingle buffer and do not have to convert each pair of data bytes to aninteger before doing arithmetic operations on the data. Internally, theIBWRTI function sends each integer to the GPIB in low-byte, high-byteorder. The IBRDI function reads a series of data bytes from the GPIBand stores them into the integer array in low-byte, high-byte order.In addition to IBRDI and IBWRTI, the asynchronous functions IBRDIAand IBWRTIA are provided to perform asynchronous integer reads andwrites.The functions are listed alphabetically by function name in this section.Table 4A.1 provides a summary of the BASICA GPIB-PC functions andTable 4A.2 provides a summary of the QuickBASIC GPIB-PC functions.BASICA/QuickBASIC "ON SRQ" CapabilityBASICA programs may be interrupted on the occurrence of the GPIBSRQ signal. When the interrupt occurs, a branch can be taken to aservice routine which determines the cause of the SRQ and takes theappropriate action.National Instruments uses this statement to intercept SRQ interrupt andmake them available to user programs. For more complete informationregarding the operation of "ON PEN", refer to the IBM BASICA User'sManual and Microsoft QuickBASIC under the "ON PEN Statement."All the information in that section applies to both the light pen and tothe GPIB SRQ signal.Statements such as "ON PEN" which intercept interrupts are a specialfeature of some versions of BASIC, including BASICA andQuickBASIC. These statements, however, are not usually a feature ofnon-BASIC languages and are not necessarily supported in otherNational Instruments language interfaces. To determine if this feature issupported in languages other than BASICA and QuickBASIC, refer tothe manual supplement that comes with that language.
