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© National Instruments Corporation C-1 GPIB-1014 User Manual
Appendix C
Sample Programs
This appendix contains listings of routines in 68000 assembly language code that implement the
essential elements of these major utility functions:
• Initialize the GPIB-1014 interface (INIT).
• Initialize the interface functions of the GPIB devices (IFC).
• Set or clear the GPIB REN line (REN).
• Accept data bytes from a Talker (RCV).
• Address Talker and read device-dependent messages (READ).
• Send data bytes to Listeners (DSEND).
• Address Listener and write device-dependent messages (WRITE).
• Send command bytes to Listeners (CSEND).
• Write interface messages (CMD).
• Pass GPIB control to another device (PASSC).
Assumptions regarding the state of the GPIB-1014 appear at the beginning of each routine and
must be adhered to for proper, error-free operation.
The following characteristics of the code must be considered:
• Standard 24-bit DMA memory addressing is used.
• The GPIB-1014 base address is FF2000 hex.
• Normal (non-extended) GPIB addressing is used.
• Timeout on subroutine calls is not implemented.
• Register values are not saved on subroutine calls.
• Program interrupt is not used; status checking is by register polling.
• Constants and variables listed in the User-Specified Constants section of the listings must be
initialized to correct values.
• In operands containing expressions, + is used in place of logical OR for convenience. An
arithmetic addition yields the same result in the instances used here.